Manual on Tuberculosis, HIV and Lung Diseases: A Practical Approach Raksha Arora, VK Arora
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Evidence-based Medicine (EBM)1

 
 
What Exactly is EBM?
Evidenced-based medicine is simply a way of ensuring that clinical decisions are based on the best available research information. The best evidence is hard to define in one sentence, but it is characterized by an emphasis on empirical research (research based on the result of different approaches to clinical management) rather than assumed effects based on understanding the pathology, physiology or microbiology. The emphasis is less on understanding why as asking whether. Too often in the past we relied on knowing what should work by attempting to understand the mechanism of illness.
 
How can I Practise EBM if There are no Randomized Controlled Trials (RCTs) to Answer My Question?
Some clinicians think ‘EBM = RCTs’, i.e. EBM is about relying on RCTs, and that unless there are RCTs for a particular question, EBM falls down. This is incorrect on several counts. First, although RCTs are the best design for answering questions of treatment (interventions), there are many other types of questions .
 
Question Types (With Typical Examples)
 
Intervention
‘What is the better of these two treatments?
 
Diagnosis
‘What is the chance of disease if this test/sign is positive/negative?’
 
Prognosis
‘If a patient has a disease at this stage and age, what is likely to happen?’
 
Aetiology
‘How does this risk factor influence the chance of getting/course of the disease?’
 
Frequency
‘How common is this disease among patients like those in my practice?
Second, whatever the question, even if the best quality evidence is not available, then whatever is best is … the best! Even if this is only the clinician's own experience, it is good to know the quality of information we are using to base decisions on.
 
What is Wrong with Experience?
The main problem is, although experience is often right, it is also often wrong. There are so many processes (e.g. biases and selective memory) that we cannot rely on experience. Doctors (including Sir William Osler) were 2convinced for about 200 years that blood letting was essential in the treatment of pneumonia. This error of experience was not just wrong, but undoubtedly harmful. In our own professional lifetimes, we have done a 180 degree change in direction on, rest for osteoarthritis (trials have found exercise is much better) or beta blockers for heart failure (previously thought to be harmful; trials now show evidence of benefit). What else do we take for granted from our experience that will change when new research is published? However, sometimes there is no better evidence than experience and we must rely on that—it is better to know when we are ‘skating on thin ice’.
 
What Types of Evidence are Best?
This depends on the information required. For choice of management, the best available evidence comes from RCTs. For diagnostic tests, other types of information will be necessary, e.g. from a consecutive series of patients given the test and the ‘gold standard’.
The best evidence comes from systematic reviews, in which all studies ever undertaken to answer a particular clinical question are combined together objectively. If the data collected are similar (there are some fine points of statistics), they can be combined into a meta-analysis (meta means ‘end’). In addition to being published in journals, meta-analyses are available in one convenient place. The largest and most useful is held in the Cochrane Library (named after Archie Cochrane).
Better than review articles, meta-analyses make it easier to establish not only if a particular management option is better, but how much better. That is a quantification of benefit (and harm, sometimes!). Examples are shown in the few case studies given below.
 
Does Evidence Exist for What We do in General Practice?
Medical literature is burgeoning with evidence. Every week research articles on the types of conditions managed in general practice are published in medical journals. The problem for clinicians is finding evidence efficiently and keeping up-to-date with the latest evidence. Estimates suggest that, well over half the therapeutic choices we make, have evidence for them already in the literature.
 
Are Review Articles EBM?
In theory, review articles (summaries of the literature on a certain topic) should help guide us through the literature. The problem is that they are often incorrect because they are not up-to-date, or their authors are unsystematic and therefore biased. There are countless examples of unsystematic review articles giving incorrect advice simply because the information selected by the author was selected to fit in with his/her view. Recent information may not be included or may be misinterpreted.
 
What have Guidelines to do with EBM?
Many clinicians think ‘EBM = guidelines’. Sometimes this is true—but only if the guidelines are evidence based. Plenty of clinicians practise EBM without referring to guidelines. They find their own original primary source research papers and make their judgments. Guidelines should be treated as another type of resource for research data to inform our decisions. When guidelines fulfil their best definition: systematised summaries of the research to inform clinical decisions, they are good. That is almost the same definition as a systematic review. However, guidelines are sometimes no more than opinion about best practice, i.e. experience. The essential difference between guidelines and systematic reviews (and meta-analyses) is the intention: guidelines provide guidance, whatever the state of the evidence. Guidelines can be as good as the best systematic reviews when evidence based, and as poor as the worst opinion based review article, when not.
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How can I Practise EBM in My Clinical Work?
Follow these steps in applying evidence based general practice:
  • What is the clinical question?
  • What type of evidence would answer the question?
  • Where can I find that evidence?
  • Is the evidence of good enough quality?
  • How do I put the answer into practice?
Evidence based medicine is an interesting way of practising. It requires thought to gain access to the evidence. It should be possible to discover the amount of benefit of different management options, one over the other. Quantifying the benefit (and harm) seems to be the direction in which general practice (and all medicine) is moving.
Enormous clinical judgment and skill is required to convert the evidence into a form that allows the clinician to come together with the patient, to decide on the best way of managing the problem.
Remember to check your findings with an expert (EBM expert or specialist in the field in question). If the conclusions you reach appear to be outlandish.
Sometimes you can be misled by a range of problems; from not finding the right evidence or selecting on the basis of best quality evidence, or misinterpreting the evidence. Like everything else, it takes practice.”
Evidence based medicine is difficult to master. Participating in an EBM workshop is one way to increase confidence. Another way is to join a like minded EBM journal club and learn by doing. This is the right time for the medical fraternity to start workshops on this subject or at least discuss these issues as a topic in all medical conferences so that the misuse of therapeutics is limited in the interest of the profession and the patients alike.
The following two case studies show examples that you could use, if you have a day of basing as much of your practice on evidence as you could.
We have refrained from giving all the references of the evidence from which we have quoted. Our hope is that you will be interested in finding the evidence yourself and building your confidence and skills in this area.
 
Four Case Studies as Examples
 
 
Case 1
Harish, aged 67 years, comes to see you for a repeat prescription for his chronic asthma.
‘You are still smoking, aren't you?'you ask.
‘Yep, doc, can't give up now. It's too late. Tried before and I just can't stand it. My ‘fags’ is one of my last pleasures and I know it isn't good for me. Just have to hope you will do the best for me if a cancer crops up’, he chuckles.
This macabre display of mirth starts you thinking. Would a chest X-ray pick up carcinoma of the bronchus early enough to improve Harish's chances if he developed one?
 
Question 1
What is the clinical question?
The question is: ‘Does using a chest X-ray in smokers without symptoms for early detection of lung cancer result in a better outcome than doing nothing?’
Note the question is not ‘Do chest X-rays pick-up cancer earlier?’ This would be a necessary accompaniment of the correct question, but it is not enough. You need to know the result of this in terms of patient survival and quality of life.
We want to know which of the following ‘states of evidence’ exist:
  • Is there any evidence about early detection of lung cancer leading to improved survival?
  • If yes, is the evidence good?
  • If yes, how much benefit or harm is there?
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Question 2
What type of evidence would answer the question?
For this particular question, finding the right evidence is not straightforward. Whether screening for serious disease is useful, is a difficult question to answer. To understand the reasons for this, and to ensure that the correct type of evidence is searched, it is important to understand ‘lead time bias’. This refers to the ‘extra’ time a person has if a diagnosis of their disease is identified early.
 
Question 3
Where would you find this evidence?
You will find the evidence using the Cochrane Library, accessible at www.TheCochraneLibrary.com.
The search is easy: Enter ‘screen lung cancer’ into the SEARCH box. If you click the GO button you will get far too many ‘hits’. Re-enter it and click the drop down menu to select ‘Record Title’. This will limit the search to only systemic reviews and trials that include these items in their title.
This yields one Cochrane review, three other systematic reviews and 48 trials.
It is reasonable to go for the highest level of evidence (Cochrane review) for a quick search. (For a formal academic systematic review, your search needs to be more exhaustive.)
The summary of this review is that early detection in asymptomatic men does not result in improved survival.
 
In Summary
  1. There is evidence about screening for lung cancer and improved survival.
  2. It is quite a good evidence.
  3. The evidence is that early detection in asymptomatic men does not result in improved survival.
An alternative to searching the Cochrane database would be to look for a set of guidelines. Screening is a complicated and important activity, and several international/national guidelines have been developed.
 
Question 4
How would you put the answer into practice?
Putting this into practice: don't screen asymptomatic patients for lung cancer.
 
Case Feedback
This is a good example of using guidelines. Good guidelines are available for preventive activities They are all evidence based which means that they have been based on empirical evidence (rather than on what may work based on understanding the principles or patho physiology).
 
 
Case 2
Kim is a 21-year-old university student. She complains of a sore throat.
She tells you that it started yesterday and it's ‘so sore’ when she swallows. Her problem is that she has three assignments to hand in over the next 5 days and ‘wasn't counting on this’.
She has no significant previous history. On examination there is a little inflammatory exudate. She has painful lymph nodes in the neck. Her ear drums appear normal. Her temperature is 37°C. Would you prescribe antibiotics for Kim?
 
Question 1
What is the clinical question?
Traditional teaching is to identify the organism and treat accordingly. This is a pathophysiological approach. In an evidence based approach, several questions could be asked such as:
  • Can we estimate what the organism is clinically?
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  • Can throat swabs be used to reliably identify the causative organism?
  • Are there other useful tests?
If we make no attempt to identify the organism, we could ask: ‘Is it helpful to treat a patient with antibiotics who has an inflamed throat.
Let us focus on the last question. First, we need to decide what is meant by the term ‘helpful’. What are the effects of sore throat?
Symptoms include the soreness of the throat and feeling systemically unwell. Complications include suppurative (e.g. acute otitis media, sinusitis, quinsy) and nonsuppurative (e.g. acute rheumatic fever, glomerulone phritis).
So a final question could be:
‘Will treating a patient such as Kim with antibiotics result in a reduction in length of symptoms or decreased complication rate?’
 
Question 2
Where would you find the evidence to answer your question?
Specialists could provide the answer, but most ear, nose and throat surgeons rarely see patients such as Kim (patients are only referred with chronic or serious complications of sore throat).
What do international guidelines say?
Therapeutic guidelines:
Antibiotic states that antibiotics have little to offer, yet gives detailed advice about which antibiotic to use.
Instead, go to the Cochrane Library. Searching ‘Sore throat’ in the ‘Record title’ selected search box (use the drop down menu to select ‘Record title’ from the other options) we find four Cochrane systematic reviews of which three look relevant! (We also find two other nonCochrane reviews in abstract only and 133 trials).
One of the Cochrane reviews addresses the question of antibiotics for sore throat. On opening it, you can look at the data that address each of the clinical questions. You do this by selecting the ‘Figures (full size)’ option on the left hand side and scrolling down the (long) list of different questions looked at. how many patients still have throat soreness after 3 days of antibiotics or placebo.
Note: We also selected the ‘Relative risk’ from the ‘Show statistical analysis’ option rather than ‘Peto Odds ratio’ option because this is slightly easier to apply clinically, but this is not mandatory as it is the same information.
We can summarise the findings as follows.
Fifteen studies looked at over 3500 patients. Those randomised to receive antibiotics were less likely (their relative risk being 0.72, i.e. 72% of those not receiving antibiotics) to suffer the symptom of throat soreness by day 3 of diagnosis.
Other outcomes, such as the risk of contracting acute rheumatic fever or suppurative complications, can be found in this Cochrane review.
At first sight this seems to encourage the use of antibiotics, but let us look behind the numbers.
Another analysis in the review shows that 90% of patients were better by day 7 whether they used antibiotics or not. (This is a self limiting disease.) As far as symptoms are concerned, the overall shortening of the illness that antibiotics confer is about 12 hours (and 14 hours at the time of maximal difference, at 3 days). Is it worth prescribing antibiotics and risking the chance of thrush, diarrhea and abdominal pain associated with antibiotics?
The chance of acute rheumatic fever and quinsy is so low in the developed world, perhaps the outcome of the above analysis in the review may apply to this also. The situation of rheumatic fever and quinsy in India is otherwise and as the risk of acute rheumatic fever is high in developing countries like India, it would be best treated empirically with penicillin if any streptococcal infection is suspected.
 
Question 3
How would you put the answer into practice?
As the differences between using and not using antibiotics are marginal and involve patient values, it is reasonable to involve the patient in the decision. The difficulty is in expressing the 6information to allow them to do this. The way we express this will depend on our own styles, ego ‘Kim, the chance is that antibiotics will only reduce the length of the illness by about half a day. It would reduce the chance of some complications, but these are very unlikely, also you would need to take antibiotics for about 740 episodes of sore throat to avoid a single case of middle ear infection. Bear in mind antibiotics commonly cause thrush and diarrhea. You may be better off concentrating on drugs such as aspirin or paracetamol. What do you think?’
Whether Kim decides to take the antibiotics or not, either decision is fine.
 
 
Case 3
Krishan, aged 49 years, has smoked 20 cigarettes per day since he was 16. He has tried to quit on several occasions, but has not managed to sustain being a nonsmoker for more than 3 months. He has seen recent television advertisements advocating the use of nicotine replacement therapy (NRT). He has never used any form of NRT with his previous quit attempts.
Krishan asks, ‘Is it worth ago, doctor? I heard it is expensive.
A drug company representative recently told you that there is evidence from several recent systematic reviews that NRT is effective.
 
Question 1
What is the clinical question?
Before Krishan pays out hard earned money, the questions to ask are:
  • ‘Does nicotine replacement therapy work (in comparison with no treatment) for successful smoking cessation (at 6 or 72 months)?’
  • ‘If so, by how much?’
 
Question 2
What type of evidence would answer the question? Where would you find the answer?
You realise this is a treatment question, and therefore best answered by RCTs. The Cochrane Library is the best place to search.
Being lazy, you only enter ‘nicotine’ into the search box with the ‘Record Title’ option selected in the drop menu. Surprisingly there are six Cochrane reviews (and 10 other systematic reviews and 1264 trials), but only one fits the bill—Nicotine replacement therapy for smoking cessation.
 
Question 3
Summary data from the systematic review of randomized trials you find is included in Table . What do ‘odds ratio’ and ’95% confidence intervals’ mean?
The odds ratio is the ratio of the intervention (NRT using) divided by the control (placebo using) odds.
The odds is the number of nonsmokers at the end of the trial divided by the number of smokers. The odds ratio compares the odds of being a nonsmoker 6-12 months following the use of NRT versus to placebo.
Table shows that there are about twice as many nonsmokers among those using NRT than among those using the placebo at the end of the trial. So using NRT approximately doubled the chances of successfully giving up smoking.
Confidence intervals are a useful way of accounting for the size of the sample (smaller samples result in less confidence of the result, and hence wider confidence intervals), and the variability of the results - (‘noisy’, i.e. more variable samples, similarly result in less confidence of the result, and hence wider confidence intervals).
The figures in brackets in Table are the 95% confidence intervals. This is a statistical measure of the certainty that the figures are correct, ego in the case of nicotine gum, we are 95% sure that the odds ratio lies 1.52-1.81; that there is only a 5:100 or 1 :20 probability that the figure would lie outside this range by chance alone.7
Table Summary data from systemic review of NRT trials
Number of trials
Odds ratio (and the 95% confidence interval)
Nicotine gum
52
166 (152-1.81)
Nicotine patch
38
1.81 (1.63-2.02)
Nicotine inhaler
4
2.14 (1.44-3.18)
 
Question 4
Given the figures in Table, how would you answer Krishan about whether NRT works?
The evidence from the systematic review of RCTs clearly indicates that if Krishan uses NRT he will nearly double (around 1.66-2.14, depending how the nicotine is delivered) his chance of quitting for 6-12 months.
A widely quoted figure for the success of giving up with nothing more than simple advice from a GP is about 4-6%. This means Krishan's absolute chance of giving up on this occasion is multiplying this by 2, or about 8-12%.
 
Question 5
What is meant by the term ‘number needed to treat’ (NNT).
Another way to express the same benefit is to ask the following question: ‘How many patients would you need to treat with each of the three forms of NRT in order to result in one extra patient being a nonsmoker at 6-72 months compared with using placebo?’
This uses the difference between rates for intervention and control. If the rate of smoking cessation with advice alone is 6% and the rate with nicotine gum is 12%, the difference is 6%. This means that offering nicotine gum to 100 people trying to give up smoking will result in six succeeding because of the gum. 6/100 is the same as 1 out of 17. Out of every 17 people offered NRT, one will succeed. This measure of the absolute risk is called the number needed to treat (NNT). Clinicians find this a useful measure of the size of effect.
Note: the NNT = l/event rate difference.
 
Question 6
You would put the answer to your clinical question into practice by asking: ‘What additional factors (if any) do I need to take into account in making a treatment decisio for Krishan?’
Recommending a particular form of treatment to a patient needs to take into account factors in addition to the evidence of effectiveness. These include:
  • Needs and preferences of the patient
  • Costs associated with treatment
  • Likely compliance with therapy, and
  • Potential side effect profile.
Smokers who have manual jobs and perspire may prefer to use nicotine gum because of the practical problems associated with adherence of the patches to the skin. Smokers who are concerned about stigmatisation associated with using an oral medication may prefer to use the patch. In each case, these decisions should be negotiated with the patient after considering the evidence of effectiveness for each. of the therapeutic options, as well as the other factors that influence the likely use of the products.
Notice how far the evidence has taken us. We have been able to provide Krishan with information that will help him feel well informed that NRT is effective and by how much.
 
Case Feedback
Once again notice how the range of acceptable options is wider when the evidence suggests that one form of management has little benefit over another. This is the area of discretionary choice. This is an example where there is no mandatory management. What if Kim elected to have the treatment? Fine. She would have decided that the (small) benefits outweighed the costs (both financial and in terms of side effects). The evidence can only assist the patient and doctor come to agreement about the best treatment for that particular episode for that particular person. Previous research has shown how GPs take the patient's psychosocial factors as seriously as their clinical ones.8
Finding the evidence enables some estimate of the size of the benefit—not just whether the balance is for or against.
Available evidence based guidelines for Respiratory Diseases are:
  1. GINA guidelines for Asthma
  2. GOLD guidelines for COPD
  3. IDSA guidelines for acute pneumonia
  4. ACCP guidelines for lung cancer
  5. International Standards for TB care (Given in Annexure)
These guidelines are only the directions and one may have to make innovative adjustments depending on the sociocultural and economic factors of different regions and countries. Some of these guidelines are required to be changed based on the research. These recommendations are to be upgraded from time to time.
 
REFERENCES
 
Internet Resources:
  1. Cochrane Library www.TheCochraneLibrary.com PubMed Clinical Queries www.ncbi.nlm.nih.gov/pubmed/
    (This is the National Library of Medicine's free MEDLINE search site with the database prefiltered for the best evidence for different types of clinical questions: diagnosis, treatment. aetiology or frequency.)
  2. Centre for Evidence-Based Medicine www.cebm.net/
    (The Centre for Evidence-Based Medicine, in Oxford, aims to promote evidence based health care and provide support and resources to anyone who wants to make use of them.
    The centre's website contains an EBM toolbox at www.cebin.net/index.aspx?o=1023. This has numerous aids to the practice and teaching of EBM, including pre-test probabilities, likelihood ratios, numbers needed to treat and other measures of effectiveness for diagnostic tests, therapy and prognosis, tips on asking clinical questions, searching and clinical appraisal and a glossary of EBM terms.
    Bandolier is a website about the use of evidence in health, healthcare, and medicine by a team based in the John Radcliffe Hospital in Oxford. It contains information about EBM and how to use it (Learning Zone section). a glossary of EBM terms, a NNT calculator worksheet. free articles from the Bandolier journal, summaries of good quality evidence under a variety of different headings (knowledge library section) and evidenced based information for consumers on various health topics (healthy living section).
 
NHS Public Health Resource Unit
  1. Appraised tools developed by the Critical Appraisal Skills Program (CASP) are available at www.phru.nhs.uk/Pages/PHD/resources.htm.
 
Critical Appraisal and ‘How to’ Texts
  1. Straus SE. Richardson WS, Glasziou P, et al. Evidence based medicine. How to practice and teach EBM. 3rd ed. Edinburgh: Churchill Livingstone, 2005.
  2. Glasziou P, Del Mar C, Salisbury J. Evidence based medicine workbook Finding and applying the best research evidence to improve patient care. 2nd ed. London: BMJ Books Blackwell, 2007.
  3. Moore A. McQuay H. Bandolier's little book of making sense of the medical evidence. Oxford: Oxford University Press, 2006.
 
EBM Journals and Summary Resources
  1. ACP Journal Club. American College of Physicians. Evidence based medicine BMJ Publishing Group. Available at ebm.bmj.com/.
  2. BMJ Clinical Evidence. BMJ publishing group Provides systematic reviews offering evidence interventions and answering clinical questions available in a range of formats including BMJ Clinical evidence handbook print version published twice yearly, database on PDA or online version. Available at clinicalevidence.bmj.com.
  3. Goroll A. May ML, Murray AG. Primary care medicine: office evaluation and management of the adult patient. 3rd ed. Lippincott: Philadelphia, 1995.
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ANNEXURE
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SUMMARY
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The purpose of the International Standards for Tuberculosis Care (ISTC) is to describe a widely accepted level of care that all practitioners, public and private, should seek to achieve in managing patients who have, or are suspected of having, tuberculosis. The Standards are intended to facilitate the effective engagement of all care providers in delivering high-quality care for patients of all ages, including those with sputum smear-positive, sputum smear-negative, and extrapulmonary tuberculosis, tuberculosis caused by drug-resistant Mycobacterium tuberculosis complex (M. tuberculosis) organisms, and tuberculosis combined with human immunodeficiency virus (HIV) infection.
The basic principles of care for persons with, or suspected of having, tuberculosis are the same worldwide: a diagnosis should be established promptly and accurately; standardized treatment regimens of proven efficacy should be used with appropriate treatment support and supervision; the response to treatment should be monitored; and the essential public health responsibilities must be carried out. Prompt, accurate diagnosis and effective treatment are not only essential for good patient care—they are the key elements in the public health response to tuberculosis and the cornerstone of tuberculosis control. Thus, all providers who undertake evaluation and treatment of patients with tuberculosis must recognize that, not only are they delivering care to an individual, they are assuming an important public health function that entails a high level of responsibility to the community, as well as to the individual patient.
Although government tuberculosis program providers are not exempt from adherence to the Standards, non-program providers are the main target audience. It should be emphasized, however, that national and local tuberculosis control programs may need to develop policies and procedures that enable non-program providers to adhere to the Standards. Such accommodations may be necessary, for example, to facilitate treatment supervision and contact investigations.
In addition to health care providers and government tuberculosis programs, both patients and communities are part of the intended audience. Patients are increasingly aware of and expect that their care will measure up to a high standard as described in the PatientsCharter for Tuberculosis Care. Having generally agreed-upon standards will empower patients to evaluate the quality of care they are being provided. Good care for individuals with tuberculosis is also in the best interest of the community.
The Standards are intended to be complementary to local and national tuberculosis control policies that are consistent with World Health Organization (WHO) recommendations. They are not intended to replace local guidelines and were written to accommodate local differences in practice. They focus on the contribution that good clinical care of individual patients with or suspected of having tuberculosis makes to population-based tuberculosis control. A balanced approach emphasizing both individual patient care and public health principles of disease control is essential to reduce the suffering and economic losses from tuberculosis.
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The Standards should be viewed as a living document that will be revised as technology, resources, and circumstances change. As written, the Standards are presented within a context of what is generally considered to be feasible now or in the near future.
The Standards are also intended to serve as a companion to and support for the Patients’ Charter for Tuberculosis Care developed in tandem with the Standards. The Charter specifies patients’ rights and responsibilities and will serve as a set of standards from the point of view of the patient, defining what the patient should expect from the provider and what the provider should expect from the patient.
 
Standards for Diagnosis
Standard 1.
All persons with otherwise unexplained productive cough lasting two–three weeks or more should be evaluated for tuberculosis.
Standard 2.
All patients (adults, adolescents, and children who are capable of producing sputum) suspected of having pulmonary tuberculosis should have at least two, and preferably three, sputum specimens obtained for microscopic examination. When possible, at least one early morning specimen should be obtained.
Standard 3.
For all patients (adults, adolescents, and children) suspected of having extrapulmonary tuberculosis, appropriate specimens from the suspected sites of involvement should be obtained for microscopy and, where facilities and resources are available, for culture and histopathological examination.
Standard 4.
All persons with chest radiographic findings suggestive of tuberculosis should have sputum specimens submitted for microbiological examination.
Standard 5.
The diagnosis of sputum smear-negative pulmonary tuberculosis should be based on the following criteria: at least three negative sputum smears (including at least one early morning specimen); chest radiography findings consistent with tuberculosis; and lack of response to a trial of broadspectrum antimicrobial agents. (NOTE: Because the fluoroquinolones are active against M. tuberculosis complex and, thus, may cause transient improvement in persons with tuberculosis, they should be avoided). For such patients, if facilities for culture are available, sputum cultures should be obtained. In persons with known or suspected HIV infection, the diagnostic evaluation should be expedited.
Standard 6.
The diagnosis of intrathoracic (i.e. pulmonary, pleural, and mediastinal or hilar lymph node) tuberculosis in symptomatic children with negative sputum smears should be based on the finding of chest radiographic abnormalities consistent with tuberculosis and either a history of exposure to an infectious case or evidence of tuberculosis infection (positive tuberculin skin test or interferon gamma release assay). For such patients, if facilities for culture are available, sputum specimens should be obtained (by expectoration, gastric washings, or induced sputum) for culture.
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Standards for Treatment
Standard 7.
Any practitioner treating a patient for tuberculosis is assuming an important public health responsibility. To fulfill this responsibility the practitioner must not only prescribe an appropriate regimen but, also, be capable of assessing the adherence of the patient to the regimen and addressing poor adherence when it occurs. By so doing, the provider will be able to ensure adherence to the regimen until treatment is completed.
Standard 8.
All patients (including those with HIV infection) who have not been treated previously should receive an internationally accepted first-line treatment regimen using drugs of known bioavailability. The initial phase should consist of two months of isoniazid, rifampicin, pyrazinamide, and ethambutol. The preferred continuation phase consists of isoniazid and rifampicin given for four months. Isoniazid and ethambutol given for six months is an alternative continuation phase regimen that may be used when adherence cannot be assessed, but it is associated with a higher rate of failure and relapse, especially in patients with HIV infection.
The doses of antituberculosis drugs used should conform to international recommendations. Fixed-dose combinations of two (isoniazid and rifampicin, three (isoniazid, rifampicin, and pyrazinamide), and four (isoniazid, rifampicin, pyrazinamide, and ethambutol) drugs are highly recommended, especially when medication ingestion is not observed.
Standard 9.
To foster and assess adherence, a patient-centered approach to administration of drug treatment, based on the patient's needs and mutual respect between the patient and the provider, should be developed for all patients. Supervision and support should be gender-sensitive and age-specific and should draw on the full range of recommended interventions and available support services, including patient counseling and education. A central element of the patient-centered strategy is the use of measures to assess and promote adherence to the treatment regimen and to address poor adherence when it occurs. These measures should be tailored to the individual patient's circumstances and be mutually acceptable to the patient and the provider. Such measures may include direct observation of medication ingestion (directly observed therapy—DOT) by a treatment supporter who is acceptable and accountable to the patient and to the health system.
Standard 10.
All patients should be monitored for response to therapy, best judged in patients with pulmonary tuberculosis by follow-up sputum microscopy (two specimens) at least at the time of completion of the initial phase of treatment (two months), at five months, and at the end of treatment. Patients who have positive smears during the fifth month of treatment should be considered as treatment failures and have therapy modified appropriately. (See Standards 14 and 15). In patients with extrapulmonary tuberculosis and in children, the response to treatment is best assessed clinically. Followup radiographic examinations are usually unnecessary and may be misleading.
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Standard 11.
A written record of all medications given, bacteriologic response, and adverse reactions should be maintained for all patients.
Standard 12.
In areas with a high prevalence of HIV infection in the general population and where tuberculosis and HIV infection are likely to co-exist, HIV counseling and testing is indicated for all tuberculosis patients as part of their routine management. In areas with lower prevalence rates of HIV, HIV counseling and testing is indicated for tuberculosis patients with symptoms and/or signs of HIV-related conditions and in tuberculosis patients having a history suggestive of high-risk of HIV exposure.
Standard 13.
All patients with tuberculosis and HIV infection should be evaluated to determine if antiretroviral therapy is indicated during the course of treatment for tuberculosis. Appropriate arrangements for access to antiretroviral drugs should be made for patients who meet indications for treatment. Given the complexity of co-administration of antituberculosis treatment and antiretroviral therapy, consultation with a physician who is expert in this area is recommended before initiation of concurrent treatment for tuberculosis and HIV infection, regardless of which disease appeared first. However, initiation of treatment for tuberculosis should not be delayed. Patients with tuberculosis and HIV infection should also receive cotrimoxazole as prophylaxis for other infections.
Standard 14.
An assessment of the likelihood of drug resistance, based on history of prior treatment, exposure to a possible source case having drug-resistant organisms, and the community prevalence of drug resistance, should be obtained for all patients. Patients who fail treatment and chronic cases should always be assessed for possible drug resistance. For patients in whom drug resistance is considered to be likely, culture and drug susceptibility testing for isoniazid, rifampicin, and ethambutol should be performed promptly.
Standard 15.
Patients with tuberculosis caused by drug-resistant (especially multiple drug resistant [MDR]) organisms should be treated with specialized regimens containing second-line antituberculosis drugs. At least four drugs to which the organisms are known or presumed to be susceptible should be used, and treatment should be given for at least 18 months. Patientcentered measures are required to ensure adherence. Consultation with a provider experienced in treatment of patients with MDR tuberculosis should be obtained.
 
Standards for Public Health Responsibilities
Standard 16.
All providers of care for patients with tuberculosis should ensure that persons (especially children under 5 years of age and persons with HIV infection) who are in close contact with patients who have infectious tuberculosis are evaluated and managed in line with international recommendations. Children under 5 years of age and persons with HIV infection who have been in contact with an infectious case should be evaluated for both latent infection with M. tuberculosis and for active tuberculosis.
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Standard 17.
All providers must report both new and retreatment tuberculosis cases and their treatment outcomes to local public health authorities, in conformance with applicable legal requirements and policies.
 
Research Needs
As part of the process of developing the ISTC, several key areas that require additional research were identified. Systematic reviews and research studies (some of which are underway currently) in these areas are critical to generate evidence to support rational and evidence-based care and control of tuberculosis. Research in these operational and clinical areas serves to complement ongoing efforts focused on developing new tools for tuberculosis control.
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Introduction
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Purpose
The purpose of the International Standards for Tuberculosis Care (ISTC) is to describe a widely accepted level of care that all practitioners, public and private, should seek to achieve in managing patients who have, or are suspected of having, tuberculosis. The Standards are intended to facilitate the effective engagement of all care providers in delivering high-quality care for patients of all ages, including those with sputum smear-positive, sputum smear-negative, and extrapulmonary tuberculosis, tuberculosis caused by drug-resistant Mycobacterium tuberculosis complex (M. tuberculosis) organisms, and tuberculosis combined with HIV infection. A high standard of care is essential to restore the health of individuals with tuberculosis, to prevent the disease in their families and others with whom they come into contact, and to protect the health of communities.1 Substandard care will result in poor patient outcomes, continued infectiousness with transmission of M. tuberculosis to family and other community members, and generation and propagation of drug resistance. For these reasons, substandard care is not acceptable.
The standards in this document differ from existing guidelines in that standards present what should be done, whereas, guidelines describe how the action is to be accomplished. Standards provide the foundation on which care can be based; guidelines provide the framing for the whole structure of care. Guidelines and standards are, thus, complementary to one another. A standard does not provide specific guidance on disease management but, rather, presents a principle or set of principles that can be applied in nearly all situations. In general, standards do not require adaptation to local circumstances. Guidelines must be tailored to local conditions. In addition, a standard can be used as an indicator of the overall adequacy of disease management against which individual or collective practices can be measured, whereas guidelines are intended to assist providers in making informed decisions about appropriate health interventions.2
The basic principles of care for persons with, or suspected of having, tuberculosis are the same worldwide: a diagnosis should be established promptly and accurately; standardized treatment regimens of proven efficacy should be used with appropriate treatment support and supervision; the response to treatment should be monitored; and the essential public health responsibilities must be carried out. Prompt, accurate diagnosis and effective treatment are not only essential for good patient care—they are the key elements in the public health response to tuberculosis and are the cornerstone of tuberculosis control. Thus, all providers who undertake evaluation and treatment of patients with tuberculosis must recognize that, not only are they delivering care to an individual, they are assuming an important public health function that entails a high level of responsibility to the community, as well as to the individual patient. Adherence to the standards in this document will enable these responsibilities to be fulfilled.
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Audience
The Standards are addressed to all health care providers, private and public, who care for persons with proven tuberculosis or with symptoms and signs suggestive of tuberculosis. In general, providers in government tuberculosis programs that follow existing international guidelines are in compliance with the Standards. However, in many instances (as described under Rationale), clinicians (both private and public) who are not part of a tuberculosis control program lack the guidance and systematic evaluation of outcomes provided by government control programs, and commonly, would not be in compliance with the Standards. Thus, although government program providers are not exempt from adherence to the Standards, non-program providers are the main target audience. It should be emphasized, however, that national and local tuberculosis control programs may need to develop policies and procedures that enable non-program providers to adhere to the Standards. Such accommodations may be necessary, for example, to facilitate treatment supervision and contact investigations.
In addition to health care providers and government tuberculosis programs, both patients and communities are part of the intended audience. Patients are increasingly aware of and expect that their care will measure up to a high standard as described in the PatientsCharter for Tuberculosis Care. Having generally agreed-upon standards will empower patients to evaluate the quality of care they are being provided. Good care for individuals with tuberculosis is also in the best interest of the community. Community contributions to tuberculosis care and control are increasingly important in raising public awareness of the disease, providing treatment support, encouraging adherence, reducing the stigma associated with having tuberculosis, and demanding that health care providers in the community adhere to a high standard of tuberculosis care.3 The community should expect that care for tuberculosis will be up to the accepted standard.
 
Scope
Three categories of activities are addressed by the Standards: diagnosis, treatment, and public health responsibilities of all providers. Specific prevention approaches, laboratory performance, and personnel standards are not addressed. The Standards are intended to be complementary to local and national tuberculosis control policies that are consistent with World Health Organization (WHO) recommendations. They are not intended to replace local guidelines and were written to accommodate local differences in practice. They focus on the contribution that good clinical care of individual patients with, or suspected of having, tuberculosis makes to population-based tuberculosis control. A balanced approach emphasizing both individual patient care and public health principles of disease control is essential to reduce the suffering and economic losses from tuberculosis.
To meet the requirements of the Standards, approaches and strategies (guidelines), determined by local circumstances and practices and developed in collaboration with local and national public health authorities, will be necessary. There are many situations in which the level of care can, and should, go beyond what is specified in the Standards. Local conditions, practices, and resources also will determine the degree to which this is the case.
The Standards are also intended to serve as a companion to and support for the PatientsCharter for Tuberculosis Care (http://www.worldcarecouncil.org) developed in tandem with the ISTC. This Charter specifies patients’ rights and responsibilities and will serve as a set of standards from the point of view of the patient, defining what the patient should expect from the provider and what the provider should expect from the patient.
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There are several critical areas that the Standards do not address. Their exclusion should not be regarded as an indication of their lack of importance but, rather, their being beyond the scope of this document. The Standards do not address the extremely important concern with overall access to care. Obviously, if there is no care available, the quality of care is not relevant. Additionally, there are many factors that impede access even when care is available: poverty, gender, stigma, and geography are prominent among the factors that interfere with persons seeking or receiving care. Also, if the residents of a given area perceive that the quality of care provided by the local facilities is substandard, they will not seek care there. This perception of quality is a component of access that adherence to the Standards will address.1
Also not addressed by the Standards is the necessity of having a sound, effective government tuberculosis control program. The requirements of such programs are described in a number of international recommendations from the WHO, the US Centers for Disease Control and Prevention (CDC), and the International Union Against Tuberculosis and Lung Disease (The Union). Having an effective control program at the national or local level with linkages to non-program providers enables bidirectional communication of information including case notification, consultation, patient referral, provision of drugs or services such as treatment supervision/support for private patients, and contact evaluation. In addition, the program may be the only source of laboratory services to the private sector.
In providing care for patients with, or suspected of having, tuberculosis, clinicians and persons responsible for healthcare facilities should take measures that reduce the potential for transmission of M. tuberculosis to health care workers and to other patients by following either local, national, or international guidelines for infection control. This is especially true in areas or specific populations with a high prevalence of HIV infection. Detailed recommendations are contained in the WHO Guidelines for Prevention of Tuberculosis in Health Care Facilities in Resource-Limited Settings, and the updated CDC guidelines for preventing the transmission of M. tuberculosis in health care settings.4,5
The Standards should be viewed as a living document that will be revised as technology, resources, and circumstances change. As written, the Standards are presented within a context of what is generally considered to be feasible now or in the near future. Within the Standards, priorities may be set that will foster appropriate incremental changes. For example, rather than expecting full implementation of all diagnostic elements at once, priorities should be set based on local circumstances and capabilities. Pursuing this example, once high-quality sputum smear microscopy is universally available, the first priority activity to be accomplished would be performing sputum cultures for persons suspected of having tuberculosis but who have negative sputum smears, especially those in areas of high HIV prevalence. The second priority would consist of obtaining cultures and drug susceptibility testing for patients at high-risk of having tuberculosis caused by drug-resistant organisms. A third priority would be performing cultures for all persons suspected of having tuberculosis. In some settings, as a fourth priority, drug susceptibility testing should be performed for isolates of M. tuberculosis obtained from patients not responding to standardized treatment regimens and, finally, for initial isolates from all patients.
 
Rationale
Although in the past decade there has been substantial progress in the development and implementation of the strategies necessary for effective tuberculosis control, the disease remains an enormous and growing global health problem.69 One-third of the 18world's population is infected with M. tuberculosis, mostly in developing countries, where 95% of cases occur.8 In 2003, there were an estimated 8.8 million new cases of tuberculosis, of which 3.9 million were sputum smear-positive and, thus, highly infectious.6,7 The number of tuberculosis cases that occur in the world each year is still growing, although the rate of increase is slowing. In the African region of the WHO, the tuberculosis case rate continues to increase, both because of the epidemic of HIV infection in sub-Saharan countries and the poor or absent primary care services in parts of the region.6,7 In Eastern Europe, after a decade of increases, case rates have only recently reached a plateau, the increases being attributed to the collapse of the public health infrastructure, increased poverty, and other socioeconomic factors complicated further by the high prevalence of drug-resistant tuberculosis.6,7,9 In many other countries, because of incomplete application of effective care and control measures, tuberculosis case rates are either stagnant or decreasing more slowly than should be expected. This is especially true in high-risk groups such as persons with HIV infection, the homeless, prisoners, and recent immigrants. The failure to bring about a more rapid reduction in tuberculosis incidence, at least in part, relates to a failure to fully engage non-tuberculosis control program providers in the provision of highquality care, in coordination with local and national control programs.
It is widely recognized that many providers are involved in the diagnosis and treatment of tuberculosis.1013 Traditional healers, general and specialist physicians, nurses, clinical officers, academic physicians, unlicensed practitioners, physicians in private practice, practitioners of alternative medicine, and community organizations, among others, all play roles in tuberculosis care and, therefore, in tuberculosis control. In addition, other public providers, such as those working in prisons, army hospitals, or public hospitals and facilities, regularly evaluate persons suspected of having tuberculosis and treat patients who have the disease.
Little is known about the adequacy of care delivered by non-program providers, but evidence from studies conducted in many different parts of the world show great variability in the quality of tuberculosis care, and poor quality care continues to plague global tuberculosis control efforts.11 A recent global situation assessment reported by WHO suggested that delays in diagnosis were common.12 The delay was more often in receiving a diagnosis rather than in seeking care, although both elements are important.14 This survey and other studies also show that clinicians, in particular those who work in the private health care sector, often deviate from standard, internationally recommended, tuberculosis management practices.11,12 These deviations include: under-utilization of sputum microscopy for diagnosis, generally associated with over-reliance on radiography; use of non-recommended drug regimens, with incorrect combinations of drugs and mistakes in both drug dosage and duration of treatment; and failure to supervise and assure adherence to treatment.11,12,1521 Anecdotal evidence also suggests over-reliance on poorly validated or inappropriate diagnostic tests, such as serologic assays, often in preference to conventional bacteriological evaluations.
Together these findings highlight flaws in health care practices that lead to substandard tuberculosis care for populations that, sadly, are most vulnerable to the disease and are least able to bear the consequences of such systemic failures. Any person anywhere in the world who is unable to access quality health care should be considered vulnerable to tuberculosis and its consequences.1 Likewise, any community with no or inadequate access to appropriate diagnostic and treatment services for tuberculosis is a vulnerable community.1 The development of the ISTC is an attempt to reduce vulnerability of individuals and communities to tuberculosis by promoting high-quality care for persons with, or suspected of having, tuberculosis.
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Companion and Reference Documents
The Standards in this document are complementary to two other important companion documents. The fi rst, PatientsCharter for Tuberculosis Care (http://www.worldcarecouncil.org), specifies the rights and responsibilities of patients and has been developed in tandem with this document. Second, the International Council of Nurses has developed a set of standards, TB/MDR-TB Nursing Standards (www.icn.ch/tb/standards.htm), that define in detail the critical roles and responsibilities of nurses in the care and control of tuberculosis. As a single-source reference for many of the practices for tuberculosis care, we refer the reader to Tomans Tuberculosis: Case Detection, Treatment, and Monitoring (second edition).22
There are many guidelines and recommendations on various aspects of tuberculosis care and control (For listing, see http://www.nationaltbcenter.edu/international/). The Standards draw from many of these documents to provide their evidence base. In particular, we have relied on guidelines that are generally accepted because of the process by which they were developed, and by their broad use. However, existing guidelines, although implicitly based on standards, do not present standards that define the acceptable level of care in such a way as to enable assessment of the adequacy of care by patients themselves, by communities, and by public health authorities.
In providing the evidence base for the Standards, generally we have cited summaries, meta-analyses, and systematic reviews of evidence that have examined and synthesized primary data, rather than referring to the primary data itself. Throughout the document we have used the terminology recommended in the “Revised International Definitions in Tuberculosis Control”.23
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Standards for Diagnosis
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Standard 1.
All persons with otherwise unexplained productive cough lasting two-three weeks or more should be evaluated for tuberculosis.
Rationale and Evidence Summary—
The most common symptom of pulmonary tuberculosis is persistent, productive cough, often accompanied by systemic symptoms, such as fever, night sweats, and weight loss. In addition, findings such as lymphadenopathy, consistent with concurrent extrapulmonary tuberculosis, may be noted, especially in patients with HIV infection.
Although most patients with pulmonary tuberculosis have cough, the symptom is not specific to tuberculosis; it can occur in a wide range of respiratory conditions, including acute respiratory tract infections, asthma, and chronic obstructive pulmonary disease. Although the presence of cough for 2-3 weeks is nonspecific, traditionally, having cough of this duration has served as the criterion for defining suspected tuberculosis and is used in most national and international guidelines, particularly in areas of moderate- to high-prevalence of tuberculosis.2225
In a recent survey conducted in primary health care services of nine low- and middle income countries, respiratory complaints, including cough, constituted on average 18.4% of symptoms that prompted a visit to a health center for persons older than 5 years of age. Of this group, 5% of patients overall were categorized as possibly having tuberculosis because of the presence of an unexplained cough for more than 2-3 weeks.26 Other studies have shown that 4-10% of adults attending outpatient health facilities in developing countries may have a persistent cough of more than 2-3 weeks in duration.27 This percentage varies somewhat, depending on whether there is active questioning concerning the presence of cough. Respiratory conditions, therefore, constitute a substantial proportion of the burden of diseases in patients presenting to primary health care services.26,27
Data from India, Algeria, and Chile generally show that the percentage of patients with positive sputum smears increases with increasing duration of cough from 1-2 weeks, increasing to 3-4, and > 4 weeks.28 However, in these studies even patients with shorter duration of cough had an appreciable prevalence of tuberculosis. A more recent assessment from India demonstrated that by using a threshold of > 2 weeks to prompt collection of sputum specimens, the number of patients with 21suspected tuberculosis increased by 61%, but more importantly, the number of tuberculosis cases identified increased by 46%, compared with a threshold of > 3 weeks.29 The results also suggested that actively inquiring as to the presence of cough in all adult clinic attendees may increase the yield of cases; 15% of patients who, without prompting, volunteered that they had cough, had positive smears, but in addition, 7% of patients who did not volunteer that they had cough, but on questioning admitted to having cough > 2 weeks, had positive smears.29
Choosing a threshold of 2-3 weeks is an obvious compromise, and it should be recognized that, while using this threshold reduces the clinic and laboratory workload, some cases would be missed. In patients presenting with chronic cough, the proportion of cases attributable to tuberculosis will depend on the prevalence of tuberculosis in the community.27 In countries with a low prevalence of tuberculosis, it is likely that chronic cough will be due to conditions other than tuberculosis. Conversely, in high-prevalence countries, tuberculosis will be one of the leading diagnoses to consider, together with other conditions, such as asthma, bronchitis, and bronchiectasis, that are common in many areas.
Overall, by focusing on adults and children presenting with chronic cough, the chances of identifying patients with pulmonary tuberculosis are maximized. Unfortunately, several studies suggest that not all patients with respiratory symptoms receive an adequate evaluation for tuberculosis.12,15,1720,30 These failures result in missed opportunities for earlier detection of tuberculosis and lead to increased disease severity for the patients and a greater likelihood of transmission of M. tuberculosis to family members and others in the community.
Standard 2.
All patients (adults, adolescents, and children who are capable of producing sputum) suspected of having pulmonary tuberculosis should have at least two, and preferably three, sputum specimens obtained for microscopic examination. When possible, at least one early morning specimen should be obtained.
Rationale and Evidence Summary
To prove a diagnosis of tuberculosis, every effort must be made to identify the causative agent of the disease. A microbiological diagnosis can only be confirmed by culturing M. tuberculosis complex (or, under appropriate circumstances, identifying specific nucleic acid sequences in a clinical specimen) from any suspected site of disease. In practice, however, there are many resource-limited settings in which culture is not feasible currently. Fortunately, microscopic examination of stained sputum is feasible in nearly all settings, and the diagnosis of tuberculosis can be strongly inferred by finding acid-fast bacilli by microscopic examination. In nearly all clinical circumstances in high-prevalence areas, finding acid-fast bacilli in stained sputum is highly specific and, thus, is the equivalent of a confirmed diagnosis. In addition to being highly specific for M. tuberculosis complex, identification of acid-fast bacilli by microscopic examination is particularly important for three reasons: it is the most rapid method for determining if a person has tuberculosis; it identifies persons who are at greatest risk of dying from the disease*; and it identifies the most likely transmitters of infection.
*It should be noted that in persons with HIV infection, mortality rates are greater in patients with clinically-diagnosed tuberculosis who have negative sputum smears than among HIV-infected patients who have positive sputum smears.3133
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Generally, it is the responsibility of government health systems (national tuberculosis programs [NTPs] or others) to ensure that providers and patients have convenient access to microscopy laboratories. Moreover, it is crucial that such laboratories undergo assessments of quality and have programs for quality improvement. These quality assessments are generally the responsibility of a government system (usually the NTP).
Failure to perform a proper diagnostic evaluation before initiating treatment potentially exposes the patient to the risks of unnecessary or wrong treatment with no benefit. Moreover, such an approach may delay accurate diagnosis and proper treatment. This standard applies to adults, adolescents, and children. With proper instruction and supervision, many children 5 years of age and older can generate a specimen. Adolescents, although often classified as children at least until the age of 15 years, can generally produce sputum. Thus, age alone is not sufficient justification for failing to attempt to obtain a sputum specimen from a child or adolescent.
The information summarized below describes the results of various approaches to sputum collection, processing, and examination. The application of the information to actual practices and policies should be guided by local considerations.
The optimum number of sputum specimens to establish a diagnosis has been examined in a number of studies. In a recent review of data from a number of sources, it was stated that, on average, the initial specimen was positive in about 83-87% of all patients ultimately found to have acid-fast bacilli detected, in an additional 10-12% with the second specimen, and in a further 3-5% on the third specimen.34 A rigorously conducted systematic review of 41 studies on this topic found a very similar distribution of results: on average, the second smear detected about 13% of smear-positive cases, and the third smear detected 4% of all smear-positive cases.35 In studies that used culture as the reference standard, the mean incremental yield in sensitivity of the second smear was 9% and that of the third smear was 4%.35
A recent re-analysis of data from a study involving 42 laboratories in four high-burden countries showed that the incremental yield from a third sequential smear ranged from 0.7-7.2%.36 Thus, it appears that in a diagnostic evaluation for tuberculosis, at least two specimens should be obtained. In some settings, because of practicality and logistics, a third specimen may be useful, but examination of more than three specimens adds minimally to the number of positive specimens obtained.35 In addition, a third specimen is useful as confirmatory evidence if only one of the first two smears has a positive result. Ideally, the results of sputum microscopy should be returned to the clinician within no more than one working day from submission of the specimen. The timing of specimen collection is also important. The yield appears to be greatest from early morning (overnight) specimens.35,3739 Thus, although it is not practical to collect only early morning specimens, at least one specimen should be obtained from an early morning collection.
A variety of methods have been used to improve the performance of sputum smear microscopy.4042 In general, the sensitivity of microscopy (as compared to culture) is higher with concentration by centrifugation and/or sedimentation (usually after pretreatment with chemicals such as bleach, NaOH, and NaCl) or both, as compared 23to direct (unconcentrated) smear microscopy. A comprehensive, systematic review of 83 studies describing the effects of various physical and/or chemical methods for concentrating and processing sputum prior to microscopy found that concentration resulted in a higher sensitivity (15-20% increase) and smear-positivity rate, when compared with direct smears.40 Although there are demonstrable advantages to concentration of sputum, there are also disadvantages. Centrifugation is more complex, requires electrical power, and may be associated with increased infection risk to laboratory personnel. Consequently, it is not clear that the advantages offset the disadvantages in low-resource settings.
Fluorescence microscopy, in which auramine-based staining causes the acid-fast bacilli to fluoresce against a dark background, is widely used in many parts of the world. A systematic review, in which the performance of direct sputum smear microscopy using fluorescence staining was compared with Ziehl-Neelsen (ZN) staining using culture as the gold standard, suggests that fluorescence microscopy is the more sensitive method.41 The results of this review have been verified in a more comprehensive, systematic review of 43 studies. This review showed that fluorescence microscopy is on average 10% more sensitive than conventional light microscopy.42 The specificity of fluorescence microscopy was comparable to Ziehl-Neelsen staining. The combination of increased sensitivity with little or no loss of specificity makes fluorescence microscopy a more accurate test, although the increased cost and complexity might make it less applicable in many areas. For this reason, fluorescence staining is probably best used in centers with specifically trained and proficient microscopists, in which a large number of specimens are processed daily, and in which there is an appropriate quality control program.
Standard 3.
For all patients (adults, adolescents, and children) suspected of having extrapulmonary tuberculosis, appropriate specimens from the suspected sites of involvement should be obtained for microscopy and, where facilities and resources are available, for culture and histopathological examination.
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Rationale and Evidence Summary—
Extrapulmonary tuberculosis (without associated lung involvement) accounts for 15–20% of tuberculosis in populations with a low prevalence of HIV infection. In populations with a high prevalence of HIV infection, the proportion of cases with extrapulmonary tuberculosis is higher. Because appropriate specimens may be difficult to obtain from some of these sites, bacteriological confirmation of extrapulmonary tuberculosis is often more difficult than for pulmonary tuberculosis. In spite of the difficulties, however, the basic principle that bacteriological confirmation of the diagnosis should be sought still holds. Generally, there are fewer M. tuberculosis organisms present in extrapulmonary sites, so identification of acid-fast bacilli by microscopy in specimens from these sites is less frequent and culture is more important. For example, microscopic examination of pleural fluid in tuberculous pleuritis detects acid-fast bacilli in only about 5-10% of cases, and the diagnostic yield is similarly low in tuberculous meningitis. Given the low yield of microscopy, both culture and histopathological examination of tissue specimens, such as may be obtained by needle biopsy of lymph nodes, are important diagnostic tests. In addition to the collection of specimens from the sites of suspected tuberculosis, examination of sputum and a chest fi lm may also be useful, especially in patients with HIV infection, in whom there is an appreciable frequency of subclinical pulmonary tuberculosis.43
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In patients who have an illness compatible with tuberculosis that is severe or progressing rapidly, initiation of treatment should not be delayed pending the results of microbiological examinations. Treatment should be started while awaiting results and then modified, if necessary, based on the microbiological findings.
Standard 4.
All persons with chest radiographic findings suggestive of tuberculosis should have sputum specimens submitted for microbiological examination.
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Rationale and Evidence Summary—
Chest radiography is a sensitive but nonspecific test to detect tuberculosis.44 Radiographic examination (film or fluoroscopy) of the thorax or other suspected sites of involvement may be useful to identify persons for further evaluation. However, a diagnosis of tuberculosis cannot be established by radiography alone. Reliance on the chest radiograph as the only diagnostic test for tuberculosis will result in both over-diagnosis of tuberculosis and missed diagnoses of tuberculosis and other diseases. In a study from India in which 2,229 outpatients were examined by photofluorography, 227 were classified as having tuberculosis by radiographic criteria.45,46 Of the 227,81 (36%) had negative sputum cultures, whereas of the remaining 2,002 patients, 31 (1.5%) had positive cultures. Looking at these results in terms of the sensitivity of chest radiography, 32 (20%) of 162 culture positive cases would have been missed by radiography. Given these and other data, it is clear that the use of radiographic examinations alone to diagnose tuberculosis is not an acceptable practice.
Chest radiography is useful to evaluate persons who have negative sputum smears to attempt to fi nd evidence for pulmonary tuberculosis and to identify other abnormalities that may be responsible for the symptoms. With regard to tuberculosis, radiographic examination is most useful when applied as part of a systematic approach in the evaluation of persons whose symptoms and/or findings suggest tuberculosis, but who have negative sputum smears (Standard 5).
Standard 5.
The diagnosis of sputum smear-negative pulmonary tuberculosis should be based on the following criteria: at least three negative sputum smears (including at least one early morning specimen); chest radiography findings consistent with tuberculosis; and lack of response to a trial of broad-spectrum antimicrobial agents. (NOTE: Because the fluoroquinolones are active against M. tuberculosis complex and, thus, may cause transient improvement in persons with tuberculosis, they should be avoided.) For such patients, if facilities for culture are available, sputum cultures should be obtained. In persons with known or suspected HIV infection, the diagnostic evaluation should be expedited.
Rationale and Evidence Summary—
The designation of “sputum smear-negative tuberculosis” presents a difficult diagnostic dilemma. As noted above, on average, sputum smear microscopy is only about 50-60% sensitive when compared with culture. Nevertheless, given the nonspecific nature of the symptoms of tuberculosis and the multiplicity of other diseases that could be the cause of the patient's illness, it is important that a rigorous approach be taken in diagnosing tuberculosis in a patient in whom at least three adequate sputum smears are negative. Because patients with HIV infection and tuberculosis frequently have negative sputum smears, and because of the broad differential diagnosis (including Pneumocystis jiroveci pneumonia and bacterial and fungal lower respiratory infections) in this group, such a systematic approach is crucial. It is important, however, 25to balance the need for a systematic approach, in order to avoid both over- and under-diagnosis of tuberculosis, with the need for prompt treatment in a patient with an illness that is progressing rapidly. Over-diagnosis of tuberculosis when the illness has another cause will delay proper diagnosis and treatment; whereas, under-diagnosis will lead to more severe consequences of tuberculosis, including disability and possibly death, as well as ongoing transmission of M. tuberculosis. It should be noted that in making a diagnosis based on the above three criteria, a clinician who decides to treat with a full course of antituberculosis chemotherapy should report this as a case of sputum smear-negative pulmonary tuberculosis to local public health authorities (as described in Standard 17).
A number of algorithms have been developed as a means to systematize the diagnosis of smear-negative tuberculosis, although none has been adequately validated under field conditions.47,48 In particular, there is little information or experience on which to base approaches to the diagnosis of smear-negative tuberculosis in persons with HIV infection. Flow chart 1 is modified from an algorithm developed by WHO and is included as an example of a systematic approach.24 It should be recognized that, commonly, the steps in the algorithm are not followed in a sequential fashion by a single provider. The algorithm should be viewed as presenting an approach to diagnosis that incorporates the main components of, and a framework for, the diagnostic evaluation.
There are several points of caution regarding the algorithm. First, completion of all of the steps requires a substantial amount of time; thus, it should not be used for patients with an illness that is worsening rapidly. This is especially true in patients with HIV infection in whom tuberculosis may be rapidly progressive. Second, several studies have shown that patients with tuberculosis may respond, at least transiently, to broad spectrum antimicrobial treatment.4952 Obviously, such a response will lead one to delay a diagnosis of tuberculosis. Fluoroquinolones in particular are bactericidal for M. tuberculosis complex. Empiric fluoroquinolone monotherapy for respiratory tract infections has been associated with delays in initiation of appropriate antituberculosis therapy and acquired resistance to the fluoroquinolones.53 Third, the approach outlined in the algorithm may be quite costly to the patient and deter her/him from continuing with the diagnostic evaluation. Given all these concerns, application of such an algorithm in patients with at least three negative sputum smear examinations must be done in a flexible manner. Ideally, the evaluation of smear-negative tuberculosis should be guided by locally validated approaches, suited to local conditions.
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Flow chart 1: An illustrative approach to the diagnosis of sputum smear-negative pulmonary tuberculosis24AFB = acid-fast bacilli; TB = tuberculosis Source: Modified from WHO, 200324
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Although sputum microscopy is the first bacteriologic diagnostic test of choice where resources permit and adequate, quality-assured laboratory facilities are available, culture should be included in the algorithm for evaluating patients with negative sputum smears. Properly done, culture adds a significant layer of complexity and cost but also increases sensitivity, which should result in earlier case detection.54,55 Although the results of culture may not be available until after a decision to begin treatment has to be made, treatment can be stopped subsequently if cultures from a reliable laboratory are negative, the patient has not responded clinically, and the clinician has sought other evidence in pursuing the differential diagnosis.
The probability of finding acid-fast bacilli in sputum smears by microscopy is directly related to the concentration of bacilli in the sputum. Sputum microscopy is likely to be positive when there are at least 10,000 organisms per milliliter of sputum. At concentrations below 1,000 organisms per milliliter of sputum, the chance of observing acid-fast bacilli in a smear is less than 10%.56,57 In contrast, a properly performed culture can detect far lower numbers of acid-fast bacilli (detection limit is about 100 organisms per ml).54 The culture, therefore, has a higher sensitivity than microscopy and, at least in theory, can increase case detection, although this potential has not been demonstrated in low-income, high-incidence areas. Further, culture makes it possible to identify the mycobacterial species and to perform drug susceptibility testing in patients in whom there is reason to suspect drug-resistant tuberculosis.54 The disadvantages of culture are its cost, technical complexity, and the time required to obtain a result, thereby imposing a diagnostic delay if there is less reliance on sputum smear microscopy. In addition, ongoing quality assessment is essential for culture results to be credible. Such quality assurance measures are not available widely in most low-resource settings.
In many countries, although culture facilities are not uniformly available, there is the capacity to perform culture in some areas. Providers should be aware of the local capacity and use the resources appropriately, especially for the evaluation of persons suspected of having tuberculosis who have negative sputum smears and for persons suspected of having tuberculosis caused by drug-resistant organisms.
Traditional culture methods use solid media such as Lowenstein-Jensen and Ogawa. Cultures on solid media are less technology-intensive, and the media can be made locally. However, the time to identify growth is significantly longer than in liquid media. Liquid media systems such as BACTEC® utilize the release of radioactive CO2 from C-14 labeled palmitic acid in the media to identify growth. The MGIT® system, also using liquid medium, has the advantage of having growth detected by the appearance of fluorescence in a silicone plug at the bottom of the tube, thereby avoiding radioactivity. Decisions to provide culture facilities for diagnosing tuberculosis depend on financial resources, trained personnel, and the ready availability of reagents and equipment service.
Nucleic acid amplification tests (NAATs), although widely distributed, do not offer major advantages over culture at this time. Although a positive result can be obtained more quickly than with any of the culture methods, the NAATs are not sufficiently sensitive for a negative result to exclude tuberculosis.5863 In addition, NAATs are not 28sufficiently sensitive to be useful in identifying M. tuberculosis in specimens from extrapulmonary sites of disease.5961,63 Moreover, cultures must be available if drug susceptibility testing is to be performed. Other approaches to establishing a diagnosis of tuberculosis, such as serological tests, are not of proven value and should not be used in routine practice at this time.58
Standard 6.
The diagnosis of intrathoracic (i.e. pulmonary, pleural, and mediastinal or hilar lymph node) tuberculosis in symptomatic children with negative sputum smears should be based on the finding of chest radiographic abnormalities consistent with tuberculosis and either a history of exposure to an infectious case or evidence of tuberculosis infection (positive tuberculin skin test or interferon gamma release assay). For such patients, if facilities for culture are available, sputum specimens should be obtained (by expectoration, gastric washings, or induced sputum) for culture.
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Rationale and Evidence Summary—
Children with tuberculosis commonly have paucibacillary disease without evident lung cavitation but with involvement of intrathoracic lymph nodes. Consequently, compared with adults, sputum smears from children are more likely to be negative. Therefore, cultures of sputum or other specimens, radiographic examination of the chest, and tests to detect tuberculous infection (generally, a tuberculin skin test) are of relatively greater importance. Because many children less than 5 years of age do not cough and produce sputum effectively, culture of gastric washings obtained by naso-gastric tube lavage or induced sputum has a higher yield than spontaneous sputum.64
Several recent reviews have examined the effectiveness of various diagnostic tools, scoring systems and algorithms to diagnose tuberculosis in children.6467 Many of these approaches lack standardization and validation and, thus, are of limited applicability. Table 1 presents the approach recommended by the Integrated Management of Childhood Illness (IMCI) program of WHO that is widely used in first-level facilities in low- and middle-income countries.68
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Table 1   An approach to the diagnosis of tuberculosis in children68
The risk of tuberculosis is increased when there is an active case (infectious, smear-positive tuberculosis) in the same house or when the child is malnourished, is HIV infected, or has had measles in the past few months. Consider tuberculosis in any child with:
A history of:
On examination:
• Unexplained weight loss or failure to grow normally
• Fluid on one side of the chest (reduced air entry, stony dullness to percussion)
• Unexplained fever, especially when it continues for more than two weeks
• Enlarged non-tender lymph nodes or a lymph node abscess, especially in the neck
• Chronic cough
• Signs of meningitis, especially when these develop over several days and the spinal fluid contains mostly lymphocytes and elevated protein
• Exposure to an adult with probable or definite pulmonary infectious tuberculosis
• Abdominal swelling with or without palpable lumps
• Progressive swelling or deformity in the bone or a joint, including the spine
Source: Reproduced from WHO/FCH/CAH/00.1
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Standards for Treatment
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Standard 7.
Any practitioner treating a patient for tuberculosis is assuming an important public health responsibility. To fulfill this responsibility, the practitioner must not only prescribe an appropriate regimen but, also, be capable of assessing the adherence of the patient to the regimen and addressing poor adherence when it occurs. By so doing, the provider will be able to ensure adherence to the regimen until treatment is completed.
Rationale and Evidence Summary—
As described in the Introduction, the main interventions to prevent the spread of tuberculosis in the community are the detection of patients with infectious tuberculosis and providing them with effective treatment to ensure a rapid and lasting cure. Consequently, treatment for tuberculosis is not only a matter of individual health (as is the case with, for example, treatment of hypertension or diabetes mellitus); it is also a matter of public health. Thus, all providers, public and private, who undertake to treat a patient with tuberculosis, must have the knowledge to prescribe a standard treatment regimen and the means to assess adherence to the regimen and address poor adherence to ensure that treatment is completed.69 National tuberculosis programs commonly possess approaches and tools to ensure adherence with treatment and, when properly organized, can offer these to non-program providers. Failure of a provider to ensure adherence could be equated with, for example, failure to ensure that a child receives the full set of immunizations. Communities and patients deserve to be assured that providers treating tuberculosis are doing so in accordance with this principle and are thereby meeting this standard.
Standard 8.
All patients (including those with HIV infection) who have not been treated previously should receive an internationally accepted first-line treatment regimen using drugs of known bioavailability. The initial phase should consist of two months of isoniazid, rifampicin, pyrazinamide and ethambutol.* The preferred continuation phase consists of isoniazid and rifampicin given for four months.
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Isoniazid and ethambutol given for six months is an alternative continuation phase regimen that may be used when adherence cannot be assessed but is associated with a higher rate of failure and relapse, especially in patients with HIV infection.
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The doses of antituberculosis drugs used should conform to international recommendations. Fixed-dose combinations of two (isoniazid and rifampicin), three (isoniazid, rifampicin, and pyrazinamide) and four (isoniazid, rifampicin, pyrazinamide, and ethambutol) drugs are highly recommended, especially when medication ingestion is not observed.
Rationale and Evidence Summary—
A large number of well-designed clinical trials have provided the evidence base for this Standard and several sets of treatment recommendations based on these studies have been written in the past few years.24,25,69 These are referenced and data will not be reviewed in this document. All these data indicate that a rifampicin-containing regimen is the backbone of antituberculosis chemotherapy and is highly effective in treating tuberculosis caused by drug-susceptible M. tuberculosis. It is also clear from these studies that the minimum duration of treatment for smear and/or culture-positive tuberculosis is six months. For the six-month treatment duration to be maximally effective, the regimen must include pyrazinamide during the initial two-month phase, and rifampicin must be included throughout the full six months. There are several variations in the frequency of drug administration that have been shown to produce acceptable results.24,25,69
Two systematic reviews of regimens of less than six months have found that shorter durations of treatment have an unacceptably high rate of relapse.70,71 Thus, the current international standard for smear or culture-positive tuberculosis is a regimen administered for a minimum duration of six months.24,69
Although the six-month regimen is the preferred option, an alternative continuation phase regimen, consisting of isoniazid and ethambutol given for six months, making the total duration of treatment eight months, may also be used. It should be recognized, however, that this regimen, presumably because of the shorter duration of rifampicin administration, is associated with a higher rate of failure and relapse, especially in patients with HIV infection.7274 Nevertheless, the eight-month regimen may be used when adherence to treatment throughout the continuation phase cannot be assessed.24 The rationale for this approach is that if the patient is nonadherent, the emergence of resistance to rifampicin will be minimized. A retrospective review of the outcomes of treatment of tuberculosis in patients with HIV infection shows that tuberculosis relapse is minimized by the use of a regimen containing rifampicin throughout a six-month course.72 Thus, the six-month regimen containing rifampicin throughout the entire course is preferable in patients with HIV infection to minimize the risk of relapse; however, the patient's HIV stage, the need for and availability of antiretroviral drugs, and the quality of treatment supervision/support must be considered in choosing an appropriate continuation phase of therapy.32
For the sixmonth treatment duration to be maximally effective, the regimen must include pyrazinamide during the initial two-month phase, and rifampicin must be included throughout the full six months.
Intermittent administration of antituberculosis drugs enables supervision to be provided more efficiently and economically with no reduction in efficacy. The evidence on effectiveness of intermittent regimens was reviewed recently.75,76 These reviews, based on several trials,7782 suggest that antituberculosis treatment may be given intermittently three times a week throughout the full course of therapy or twice weekly in the continuation phase without apparent loss of effectiveness. However, WHO and The Union do not recommend the use of twice-weekly intermittent regimens because of the potentially greater consequences of missing one of the two doses.24,25,83 A simplified version of the current WHO recommendations for treating persons who have not been treated previously is shown in Table 2.24
Table 2   Recommended treatment for persons not treated previously24
Ranking
Initial phase
Continuation phase
Preferred
INH, RIF, PZA, EMB 1,2 daily, 2 months
INH, RIF, PZA, EMB 1,2 3x/week, 2 months
INH, RIF daily, 4 months
INH, RIF 3x/week, 4 months
Optional
INH, RIF, PZA, EMB 2 daily, 2 months
INH, EMB daily, 6 months 3
INH = isoniazid; RIF = rifampicin; PZA = pyrazinamide; EMB = ethambutol
1Streptomycin may be substituted for ethambutol.
2Ethambutol may be omitted in the initial phase of treatment for adults and children who have negative sputum smears, do not have extensive pulmonary tuberculosis or severe forms of extrapulmonary disease, and who are known to be HIV negative.
3Associated with higher rate of treatment failure and relapse; should generally not be used in patients with HIV infection.
The evidence base for currently recommended antituberculosis drug dosages derives from human clinical trials, animal models, and pharmacokinetic and toxicity studies. The evidence on drug dosages and safety and the biological basis for dosage recommendations have been extensively reviewed in publications by WHO,24 The Union,25 ATS, CDC, the Infectious Diseases Society of America (IDSA),69 and others.83,84 The recommended doses for daily and thrice-weekly administration are shown in Table 3.
Table 3   Doses of first-line antituberculosis drugs in adults and children
Recommended dose in mg/kg body weight (range)
Drug
Daily
Three times weekly
Isoniazid
5 (4-6), maximum 300 daily
10
Rifampicin
10 (8-12), maximum 800 daily
10 (8-12), maximum 800 daily
Pyrazinamide
25 (20-30)
35 (30-40)
Ethambutol
Children 20 (15-25)* adults 15 (15-20)
30 (25-35)
Streptomycin
15 (12-18)
15 (12-18)
*The recommended daily dose of ethambutol is higher in children (20 mg/kg) than in adults (15 mg/kg), because the pharmacokinetics are different. (Peak serum ethambutol concentrations are lower in children than in adults receiving the same mg/kg dose)
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Treatment of tuberculosis in special clinical situations, such as the presence of liver disease, renal disease, pregnancy, and HIV infection, may require modifi cation of the standard regimen or alterations in dosage or frequency of drug administration. For guidance in these situations, see WHO and ATS/CDC/IDSA treatment guidelines.24,69
Although there is no evidence that fixed-dose combinations (FDCs) are superior to individual drugs, expert opinion suggests that they may minimize inadvertent monotherapy and may decrease the frequency of acquired drug resistance and medication errors.24,69 FDCs also reduce the number of tablets to be consumed and may thereby increase patient adherence to recommended treatment regimens.85,86
Standard 9.
To foster and assess adherence, a patient-centered approach to administration of drug treatment, based on the patient's needs and mutual respect between the patient and the provider, should be developed for all patients. Supervision and support should be gender-sensitive and age-specific and should draw on the full range of recommended interventions and available support services, including patient counseling and education.
A central element of the patient-centered strategy is the use of measures to assess and promote adherence to the treatment regimen and to address poor adherence when it occurs. These measures should be tailored to the individual patient's circumstances and be mutually acceptable to the patient and the provider. Such measures may include direct observation of medication ingestion (directly observed therapy—DOT) by a treatment supporter who is acceptable and accountable to the patient and to the health system.
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Rationale and Evidence Summary—
The approach described is designed to encourage and facilitate a positive partnership between providers and patients, working together to improve adherence. Adherence to treatment is the critical factor in determining treatment success.87 The success of treatment for tuberculosis, assuming an appropriate drug regimen is prescribed, depends largely on patient adherence to the regimen. Achieving adherence is not an easy task, either for the patient or the provider. Antituberculosis drug regimens, as described previously, consist of multiple drugs given for a minimum of six months, often when the patient feels well (except, perhaps, for adverse effects of the medications). Commonly, treatments of this sort are inconsistent with the patient's cultural milieu, belief system, and living circumstances. Consequently, it is not surprising that, without appropriate treatment support, a significant proportion of patients with tuberculosis discontinue treatment before completion of the planned duration or are erratic in drug taking. Yet, failure to complete treatment for tuberculosis leads to prolonged infectivity, poor outcomes, and drug resistance.88
Adherence is a multi-dimensional phenomenon determined by the interplay of five sets of factors (dimensions), as illustrated in Figure 1 and Table 4.
Despite evidence to the contrary, there is a widespread tendency to focus on patientrelated factors as the main cause of poor adherence.87 Sociological and behavioral research during the past 40 years has shown that patients need to be supported, not blamed.87 Less attention is paid to provider and health system-related factors. Several studies have evaluated various interventions to improve adherence to tuberculosis therapy. (These interventions are listed in Table 4).
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Table 4   Factors affecting adherence87
Tuberculosis
Factors affecting adherence
Interventions to improve adhrence
Social/economic factors
(–) Lack of effective social support networks and unstable living circumstances; culture and lay beliefs about illness and treatment; stigma; ethnicity, gender, and age; high cost of medication; high cost of transport; criminal justice involvement; involvement in drug dealing
Assessment of social needs, social support, housing, food tokens, and legal measures; providing transport to treatment settings; peer assistance; mobilization of community-based organizations; optimizing the cooperation between services; education of the community and providers to reduce stigma; family and community support
Health system/healthcare team factors
(–) Poorly developed health services; inadequate relationship between health care provider and patient; healthcare providers who are untrained, overworked, inadequately supervised or unsupervised in their tasks; inability to predict potentially nonadherent patients
(+) Good relationships between patient and physician; availability of expertise; links with patient support systems; flexibility in the hours of operation
Uninterrupted, ready availability of information; training and management processes that aim to improve the way providers care for patients with tuberculosis; support for local patient organizations/ groups; management of disease and treatment in conjunction with the patients; multidisciplinary care; intensive staff supervision; training in adherence monitoring; use of DOT
Condition-related factors
(–) Asymptomatic patients; drug use; altered mental states caused by substance abuse; depression and psychological stress
Education on use of medications; provision of information about tuberculosis and the need to attend for treatment
(+) Knowledge about TB Education on use of medications; provision of information about tuberculosis and the need to attend for treatment
Therapy-related factors
(–) Complex treatment regimen; adverse effects of treatment; toxicity
Education on use of medications and adverse effects of medications; adherence education; use of fixed dose combination preparations; tailor treatment support to needs of patients at risk of nonadherence; agreements (written or verbal) to return for an appointment or course of treatment; continuous monitoring and reassessment
Patient-related factors
(–) Forgetfulness; drug abuse; depression; psychological stress; isolation due to stigma
(+) Belief in the efficacy of treatment; motivation
Therapeutic relationship; mutual goal-setting; memory aids and reminders; incentives and/or reinforcements; reminder letters, telephone reminders or home visits for patients who default
DOT = directly observed therapy; TB = tuberculosis;
(+) = factors having a positive effect on adherence; (–) = factors having a negative effect on adherence
Source: Modified from WHO, 200387
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Fig. 1: The five dimensions of adherence87Source: WHO, 200387
There are a number of reviews that examine the evidence on the effectiveness of these interventions.69, 87, 89, 9095
Among the interventions evaluated, DOT has generated the most debate and controversy.* The third component of the global DOTS strategy, now widely recommended as the most effective strategy for controlling tuberculosis worldwide, is the administration of a standardized, rifampicin-based regimen using case management interventions that are appropriate to the individual and the circumstances.23,24,69,97 These interventions may include DOT as one of a range of measures to promote and assess adherence to treatment.
The main advantage of DOT is that treatment is carried out entirely under close, direct supervision.92 This provides both an accurate assessment of the degree of adherence and greater assurance that the medications have actually been ingested. When a second individual directly observes a patient swallowing medications, there is greater certainty that the patient is actually receiving the prescribed medications. This approach, therefore, results in a high cure rate and a reduction in the risk of drug resistance. Also, because there is a close contact between the patient and the treatment supporter, adverse drug effects and other complications can be identified quickly and managed appropriately.92 Moreover, such case management can also serve to identify and assist in addressing the myriad other problems experienced by patients with tuberculosis, such as undernutrition, poor housing, and loss of income, to name a few.
The exclusive use of health facility-based DOT may be associated with disadvantages that must be taken into account in designing a patient-centered approach. For example, these disadvantages may include loss of income, stigma, and physical hardship, all factors that can have an important effect on adherence.87 Ideally, a flexible mix of health facility-based and community-based DOT should be available.
In a Cochrane systematic review that synthesized the evidence from six controlled trials comparing DOT with self-administered therapy,89,90 the authors found that patients allocated to DOT and those allocated to self-administered therapy had similar cure rates (Risk Ratio [RR] 1.06, 95% Confidence Interval [CI] 0.98, 1.14); and rates of cure plus treatment completion (RR 1.06, 95% CI 1.00, 1.13). They concluded that direct observation of medication ingestion did not improve outcomes.89,90
In contrast, other reviews have found DOT to be associated with high cure and treatment completion rates.24,69,91,92,98 Also, programmatic studies on the effectiveness of the DOTS strategy have shown high rates of treatment success in several countries.87 It is likely that these inconsistencies across reviews are due to the fact that primary studies are often unable to separate the effect of DOT alone from the overall DOTS strategy.87,94 In a retrospective review of programmatic results, the highest rates of success were achieved with “enhanced DOT,” which consisted of “supervised swallowing” plus social supports, incentives, and enablers as part of a larger program to encourage adherence to treatment.91 Such complex interventions are not easily evaluated within the conventional randomized controlled trial framework.87
Interventions other than DOT have also shown promise.87,95 For example, interventions that used incentives, peer assistance, repeated motivation of patients, and staff training and motivation all have been shown to improve adherence signifi cantly.95 In addition, adherence may be enhanced by provision of more comprehensive primary care, as described in the Integrated Management of Adolescent and Adult Illness (IMAAI),99101 as well as by provision of specialized services such as opiate substitution for injection drug users.
Systematic reviews and extensive programmatic experience demonstrate that there is no single approach to case management that is effective for all patients, conditions, and settings. Consequently, interventions that target adherence must be tailored or customized to the particular situation and cultural context of a given patient.87 Such an approach must be developed in concert with the patient to achieve optimum adherence. This patient-centered, individualized approach to treatment support is now a core element of all tuberculosis care and control efforts. It is important to note that treatment support measures, and not the treatment regimen itself, must be individualized to suit the unique needs of the patient.
In addition to one-on-one support for patients being treated for tuberculosis, community support is also of importance in creating a therapeutic milieu and reducing stigma.3 Not only should the community expect that optimum treatment for tuberculosis is provided, but it also should expect and play a role in promoting conditions that facilitate and assist in ensuring that the patient will adhere to the prescribed regimen.
Standard 10.
All patients should be monitored for response to therapy, best judged in patients with pulmonary tuberculosis by follow-up sputum smear microscopy (two specimens) at least at the time of completion of the initial phase of treatment (two months), at five months, and at the end of treatment. Patients who have positive smears during the fifth month of treatment should be considered as treatment failures and have therapy modified appropriately. (See Standards 14 and 15.) In patients with extrapulmonary tuberculosis and in children, the response to treatment is best assessed clinically. Follow-up radiographic examinations are usually unnecessary and may be misleading.
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Rationale and Evidence Summary—
Patient monitoring and treatment supervision are two separate functions. Patient monitoring is necessary to evaluate the response of the disease to treatment and to identify adverse drug reactions. For the latter function, 37contact between the patient and a provider is necessary. To judge response of pulmonary tuberculosis to treatment, the most expeditious method is sputum smear microscopy. Ideally, where quality-assured laboratories are available, sputum cultures, as well as smears, should be performed for monitoring.
Having a positive sputum smear at completion of five months of treatment defi nes treatment failure, indicating the need for determination of drug susceptibility and initiation of a retreatment regimen.23 Radiographic assessments, although used commonly, have been shown to be unreliable for evaluating response to treatment.102 Similarly, clinical assessment can be unreliable and misleading in the monitoring of patients with pulmonary tuberculosis.102 In patients with extrapulmonary tuberculosis and in children, clinical evaluations may be the only available means of assessing the response to treatment.
Standard 11.
A written record of all medications given, bacteriologic response, and adverse reactions should be maintained for all patients.
Rationale and Evidence Summary—
There is a sound rationale and clear benefits of a record keeping system.103 It is common for individual physicians to believe sincerely that a majority of the patients in whom they initiate antituberculosis therapy are cured. However, when systematically evaluated, it is often seen that only a minority of patients have successfully completed the full treatment regimen.103 The recording and reporting system enables targeted, individualized follow-up to identify patients who are failing therapy.103 It also helps in facilitating continuity of care, particularly in settings (e.g. large hospitals) where the same practitioner might not be seeing the patient during every visit. A good record of medications given, results of investigations (such as smears, cultures, and chest radiographs), and progress notes (on clinical improvement, adverse events, and adherence) will provide for more uniform monitoring and ensure a high standard of care.
Records are important to provide continuity when patients move from one care provider to another and to enable tracing of patients who miss appointments. In patients who default and then return for treatment and patients who relapse after treatment completion, it is critical to review previous records in order to assess the likelihood of drug resistance. Lastly, management of complicated cases (e.g. multidrug-resistant tuberculosis) is not possible without an adequate record of previous treatment, adverse events, and drug susceptibility results. It should be noted that, wherever patient records are concerned, care must be taken to insure confidentiality of the information.
Standard 12.
In areas with a high prevalence of HIV infection in the general population where tuberculosis and HIV infection are likely to co-exist, HIV counseling and testing is indicated for all tuberculosis patients as part of their routine management. In areas with lower prevalence rates of HIV, HIV counseling and testing is indicated for tuberculosis patients with symptoms and/or signs of HIV-related conditions and in tuberculosis patients having a history suggestive of high risk of HIV exposure.
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Rationale and Evidence Summary—
Infection with HIV both increases the likelihood of progression from infection with M. tuberculosis to active tuberculosis and changes the clinical manifestations of the disease.32,104,105 Further, in comparison with non-HIV infected patients, patients 38with HIV infection who have pulmonary tuberculosis have a lower likelihood of having acid-fast bacilli detected by sputum smear microscopy.32,104,105 Moreover, data consistently show that the chest radiographic features are atypical and the proportion of extrapulmonary tuberculosis is greater in patients with advanced HIV infection compared with those who do not have HIV infection. Consequently, knowledge of a person's HIV status would influence the approach to a diagnostic evaluation for tuberculosis. For this reason, it is important, particularly in areas in which there is a high prevalence of HIV infection, that the history and physical examination include a search for indicators that suggest the presence of HIV infection. Table 5 presents clinical features that are suggestive of HIV infection.105 A comprehensive list of clinical criteria/algorithms for HIV/AIDS diagnosis and clinical staging is available in the WHO document Scaling up Antiretroviral Therapy in Resource-Limited Settings: Guidelines for a Public Health Approach (Geneva, 2002).106
Tuberculosis is highly associated with HIV infection worldwide.7,107 Although the prevalence of HIV infection varies widely among and within countries, in persons with HIV infection there is always an increased risk of tuberculosis. The differences in HIV prevalence mean that a variable percentage of patients with tuberculosis will have HIV infection as well. This ranges from less than 1% in low-HIV-prevalence countries to 50-70% in countries with a high HIV prevalence, mostly sub-Saharan African countries.7 Even though in low-HIV-prevalence countries few tuberculosis patients will be HIV-infected, the connection is sufficiently strong and the impact on the patient sufficiently great that the test should always be considered in managing individual patients, especially among groups in which the prevalence of HIV is higher, such as injecting drug users. In countries having a high prevalence of HIV infection, the yield of positive results will be high, and, again, the impact of a positive result on the patient will be great. Thus, the indication for HIV testing is strong; co-infected patients may benefit by access to antiretroviral therapy as HIV treatment programs expand or through administration of co-trimoxazole for prevention of opportunistic infections, even when antiretroviral drugs are not available locally.105,107,108
Table 5   Clinical features suggestive of HIV infection in patients with tuberculosis105
Past history
• Sexually transmitted infections (STI)
• Herpes zoster (shingles)
• Recent or recurrent pneumonia
• Severe bacterial infections
• Recent treated tuberculosis
Symptoms
• Weight loss (>10 kg or >20% of original weight)
• Diarrhea (>1 month)
• Retrosternal pain on swallowing (suggestive of esophageal candidiasis)
• Burning sensation of feet (peripheral sensory neuropathy)
Signs
• Scar of herpes zoster
• Itchy popular skin rash
• Kaposi sarcoma
• Symmetrical generalized lymphadenopathy
• Oral candidiasis
• Angular cheilitis
• Oral hairy leukoplakia
• Necrotizing gingivitis
• Giant aphthous ulceration
• Persistent painful genital ulceration
Source: Modified from WHO, 2004105
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Standard 13.
All patients with tuberculosis and HIV infection should be evaluated to determine if antiretroviral therapy is indicated during the course of treatment for tuberculosis. Appropriate arrangements for access to antiretroviral drugs should be made for patients who meet indications for treatment. Given the complexity of coadministration of antituberculosis treatment and antiretroviral therapy, consultation with a physician who is expert in this area is recommended before initiation of concurrent treatment for tuberculosis and HIV infection, regardless of which disease appeared first. However, initiation of treatment for tuberculosis should not be delayed. Patients with tuberculosis and HIV infection should also receive co-trimoxazole as prophylaxis for other infections.
Rationale and Evidence Summary—
The evidence on effectiveness of treatment for tuberculosis in patients with HIV co-infection versus those who do not have HIV infection has been reviewed extensively.24,69,72,105,109112 These reviews suggest that, in general, the outcome of treatment for tuberculosis is the same in HIV-infected and non-HIV-infected patients with the notable exception that death rates are greater among patients with HIV infection, presumably due in large part to complications of HIV infection. With two exceptions, tuberculosis treatment regimens are the same for HIV-infected and non-HIV-infected patients. The first exception is that thioacetazone, a drug used commonly in the past but no longer recommended, is contraindicated in patients with HIV infection. Thioacetazone is associated with a high risk of severe skin reactions in HIV-infected individuals and should not be used.24,105 Second, the results of treatment are better if a rifampicin-containing regimen is used throughout the six-month course of treatment.72 Thus, the six-month regimen containing rifampicin throughout the entire course is preferable in patients with HIV infection to minimize the risk of relapse; however, the patient's HIV stage, the need for (and availability of) antiretroviral drugs, and the quality of treatment supervision/support must be considered in choosing an appropriate continuation phase of therapy.
All patients with tuberculosis and HIV infection either currently are, or will be, candidates for antiretroviral therapy. Antiretroviral therapy results in remarkable reductions in morbidity and mortality in HIV-infected persons and may improve the outcomes of treatment for tuberculosis. Highly active antiretroviral therapy (HAART) is the internationally accepted standard of care for persons with advanced HIV infection.
In patients with HIV-related tuberculosis, treating tuberculosis is the fi rst priority. In the setting of advanced HIV infection, untreated tuberculosis can progress rapidly to death. As noted above, however, antiretroviral treatment may be lifesaving for patients with advanced HIV infection. Consequently, concurrent treatment may be necessary in patients with advanced HIV disease (e.g. circulating CD4+ T lymphocyte count < 200/μL). It should be emphasized, however, that treatment for tuberculosis should not be interrupted in order to initiate antiretroviral therapy, and, in patients with early stage HIV infection, it may be safer to defer antiretroviral treatment until at least the completion of the initial phase of tuberculosis treatment.105
There are a number of problems associated with concomitant therapy for tuberculosis and HIV infection. These include overlapping toxicity profiles for the drugs used, drug interactions (especially with rifamycins and protease inhibitors), potential problems with adherence to multiple medications, and immune reconstitution reactions.69,105 Consequently, consultation with an expert in HIV management is needed 40in deciding when to start antiretroviral drugs, the agents to use, and the plan for monitoring for adverse reactions and response to both therapies. (For a single-source reference on the management of tuberculosis in patients with HIV infection see the WHO manual TB/HIV: A Clinical Manual).105
Patients with tuberculosis and HIV infection should also receive co-trimoxazole (trimethoprimsulfamethoxazole) as prophylaxis for other infections. Several studies have demonstrated the benefits of cotrimoxazole prophylaxis, and this intervention is currently recommended by the WHO as part of the TB/HIV management package.105,107,113118
Standard 14.
An assessment of the likelihood of drug resistance, based on history of prior treatment, exposure to a possible source case having drug-resistant organisms, and the community prevalence of drug resistance, should be obtained for all patients. Patients who fail treatment and chronic cases should always be assessed for possible drug resistance. For patients in whom drug resistance is considered to be likely, culture and drug susceptibility testing for isoniazid, rifampicin, and ethambutol should be performed promptly.
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Rationale and Evidence Summary—
Drug resistance is largely man-made and is a consequence of sub-optimal regimens and treatment interruptions. Clinical errors that commonly lead to the emergence of drug resistance include: failure to provide effective treatment support and assurance of adherence; failure to recognize and address patient non-adherence; inadequate drug regimens; adding a single new drug to a failing regimen; and failure to recognize existing drug resistance.119 In addition, co-morbid conditions associated with reduced serum levels of antituberculosis drugs (e.g. malabsorption, rapid transit diarrhea, HIV infection, or use of antifungal agents) may also lead to the acquisition of drug resistance.119
Programmatic causes of drug resistance include drug shortages and stock-outs, administration of poor-quality drugs and lack of appropriate supervision to prevent erratic drug intake.119 Patients with drug-resistant tuberculosis can spread the disease to their contacts. Transmission of drug-resistant strains of M. tuberculosis has been well described in congregate settings and in susceptible populations, notably HIV-infected persons.120123 However, multidrug-resistant (MDR) tuberculosis (tuberculosis caused by organisms that are resistant to at least isoniazid and rifampicin) may spread in the population at large, as was shown in China, the Baltic States, and countries of the former Soviet Union.
The strongest factor associated with drug resistance is previous antituberculosis treatment, as shown by the WHO/IUATLD Global Project on Anti-TB Drug Resistance Surveillance, started in 1994.124 In previously treated patients, the odds of any resistance are at least fourfold higher and that of MDR at least tenfold higher than in new (untreated) patients.124 Patients with chronic tuberculosis (sputum-positive after retreatment) and those who fail treatment (sputum-positive after five months of treatment) are at highest risk of having MDR tuberculosis, especially if rifampicin was used throughout the course of treatment.124 Persons who are in close contact with confirmed MDR tuberculosis patients, especially children and HIV-infected individuals, also are at high risk of being infected with MDR strains. In some closed settings, prisoners, persons staying in homeless shelters and certain categories of immigrants and migrants are at increased risk of MDR tuberculosis.119124
41
Drug susceptibility testing (DST) to the first-line antituberculosis drugs should be performed in specialized reference laboratories that participate in an ongoing, rigorous quality assurance program. DST for first-line drugs is currently recommended for all patients with a history of previous antituberculosis treatment: patients who have failed treatment, especially those who have failed a standardized retreatment regimen, and chronic cases are the highest priority.119 Patients who develop tuberculosis and are known to have been in close contact with persons known to have MDR tuberculosis also should have DST performed on an initial isolate. Although HIV infection has not been conclusively shown to be an independent risk factor for drug resistance, MDR tuberculosis outbreaks in HIV settings and high mortality rates in persons with MDR tuberculosis, and HIV infection justify routine DST in all HIV-infected tuberculosis patients, resources permitting.119
Standard 15.
Patients with tuberculosis caused by drug-resistant (especially MDR) organisms should be treated with specialized regimens containing second-line antituberculosis drugs. At least four drugs to which the organisms are known or presumed to be susceptible should be used, and treatment should be given for at least 18 months. Patient-centered measures are required to ensure adherence. Consultation with a provider experienced in treatment of patients with MDR tuberculosis should be obtained.
Rationale and Evidence Summary—
Because randomized controlled treatment trials for MDR tuberculosis would be extremely difficult to design, none have been conducted. Current recommendations are, therefore, based on observational studies, general microbiological and therapeutic principles, extrapolation from available evidence from pilot MDR tuberculosis treatment projects, and expert opinion.125,126 Three strategic options for treatment of MDR tuberculosis are currently recommended by WHO: standardized regimens, empiric regimens, and individualized treatment regimens. The choice among these should be based on availability of second-line drugs and DST for first- and second-line drugs, local drug resistance patterns, and the history of use of second-line drugs.119 Basic principles involved in the design of any regimen include the use of at least four drugs with either certain or highly likely effectiveness, drug administration at least six days a week, drug dosage determined by patient weight, the use of an injectable agent (an aminoglycoside or capreomycin) for at least six months, treatment duration of 18-24 months, and DOT throughout the treatment course.
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Standardized treatment regimens are based on representative drug-resistance surveillance data or on the history of drug usage in the country. Based on these assessments, regimens can be designed that will have a high likelihood of success. Advantages include less dependency on highly technical laboratories, less reliance on highly specialized clinical expertise required to interpret DST results, simplified drug ordering, and easier operational implementation. A standardized approach is 42useful in settings where second-line drugs have not been used extensively and, consequently, where resistance levels to these drugs are low or absent.
Empiric treatment regimens are commonly used in specific groups of patients while the DST results are pending. Unfortunately, most of the available DST methods have a turnaround time of several months. Empiric regimens are strongly recommended to avoid clinical deterioration and to prevent transmission of MDR strains of M. tuberculosis to contacts while awaiting the DST results.119 Once the results of DST are known, an empiric regimen may be changed to an individualized regimen. Ongoing global efforts to address the problem of MDR tuberculosis will likely result in broader access to laboratories performing DST and a faster return of results.
Individualized treatment regimens (based on DST profiles and previous drug history of individual patients, or on local patterns of drug utilization) have the advantage of avoiding toxic and expensive drugs to which the MDR strain is resistant. However, an individualized approach requires access to substantial human, financial, and technical (laboratory) capacity. DST for second-line drugs are notoriously difficult to perform, largely because of drug instability and the fact that critical concentrations for defining drug resistance are very close to the minimal inhibitory concentration (MIC) of individual drugs.127 Laboratory proficiency testing results are not yet available for second-line drugs; as a result, little can be said about the reliability of DST for these drugs.124,127 Clinicians treating MDR tuberculosis patients must be aware of these limitations and interpret DST results with this in mind.
Current WHO recommendations for treatment of MDR tuberculosis can be found at (http://www.who.int/tb/en/).119 MDR tuberculosis treatment is a complex health intervention, and medical practitioners are strongly advised to consult colleagues experienced in the management of these patients.
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Standards for Public Health Responsibilities
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Standard 16.
All providers of care for patients with tuberculosis should ensure that persons (especially children under 5 years of age and persons with HIV infection) who are in close contact with patients who have infectious tuberculosis are evaluated and managed in line with international recommendations. Children under 5 years of age and persons with HIV infection who have been in contact with an infectious case should be evaluated for both latent infection with M. tuberculosis and for active tuberculosis.
Rationale and Evidence Summary—
The risk of acquiring infection with M. tuberculosis is correlated with intensity and duration of exposure to a person with infectious tuberculosis. Close contacts of patients with tuberculosis, therefore, are at high risk for acquiring the infection. Contact investigation is considered an important activity, both to find persons with previously undetected tuberculosis and persons who are candidates for treatment of latent tuberculosis infection (LTBI).128,129
The potential yield of contact investigation in high- and low-incidence settings has been reviewed previously.128,129 In low-incidence settings (e.g. United States), it has been found that, on average, 5-10 contacts are identified for each incident tuberculosis case. Of these, about 30% are found to have latent tuberculosis infection, and another 1-4% have active tuberculosis.128,130,131 Much higher rates of both latent infection and active disease have been reported in high-prevalence countries, where about 50% of household contacts have latent infection, and about 10-20% have active tuberculosis at the time of initial investigation.129 A recent systematic review of more than 50 studies on household contact investigations in high incidence settings showed that, on average, about 6% (range 0.5-29%; N = 40 studies) of the contacts were found to have active tuberculosis.132 The median number of household contacts that were evaluated to find one case of active tuberculosis was 19 (range 14-300).132 The median proportion of contacts found to have latent infection was 49% (range: 7-90%; N= 34 studies).132 The median number 44of contacts that were evaluated to find one person with latent tuberculosis infection was 2 (range 1-14).132 Evidence from this review suggests that contact investigation in highincidence settings is a high-yield strategy for case finding.
Among close contacts, there are certain subgroups that are particularly at high risk for acquiring the infection with M. tuberculosis and progressing rapidly to active disease—children and persons with HIV infection. Children (particularly those under the age of 5 years) are a vulnerable group, not only because of the high likelihood of progressing from latent infection to active disease, but because they are more likely to develop disseminated and serious forms of tuberculosis such as meningitis. The Union, therefore, recommends that children under the age of 5 years living in the same household as a sputum smear-positive tuberculosis patient should be targeted for preventive therapy (after exclusion of tuberculosis to prevent de facto monotherapy of tuberculosis).65,129 Similarly, contacts who have HIV infection are at substantially greater risk for progressing to active tuberculosis.
Unfortunately, lack of adequate staff and resources in many areas makes contact investigation difficult.65,129 This inability to conduct targeted contact investigations results in missed opportunities to prevent additional cases of tuberculosis, especially among children. Thus, more energetic efforts are necessary to overcome these barriers to optimum tuberculosis control practices.
Standard 17.
All providers must report both new and retreatment tuberculosis cases and their treatment outcomes to local public health authorities, in conformance with applicable legal requirements and policies.
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Rationale and Evidence Summary—
Reporting tuberculosis cases to the local tuberculosis control program is an essential public health function, and in many countries is legally mandated. Ideally, the reporting system design, supported by a legal framework, should be capable of receiving and integrating data from several sources, including laboratories and healthcare institutions, as well as individual practitioners.
An effective reporting system enables a determination of the overall effectiveness of tuberculosis control programs, of resource needs, and of the true distribution and dynamics of the disease within the population as a whole, not just the population served by the government tuberculosis control program. In most countries, tuberculosis is a reportable disease. A system of recording and reporting information on tuberculosis cases and their treatment outcomes is one of the key elements of the DOTS strategy.103 Such a system is useful not only to monitor progress and treatment outcomes of individual patients but also to evaluate the overall performance of the tuberculosis control programs, at the local, national, and global levels, and to indicate programmatic weaknesses.103
The recording and reporting system allows for targeted, individualized follow-up to help patients who are not making adequate progress (i.e. failing therapy).103 The system also allows for evaluation of the performance of the practitioner, the hospital or institution, local health system, and the country as a whole. Finally, a system of recording and reporting ensures accountability.
Although on the one hand reporting to public health authorities is essential; on the other hand it is also essential that patient confidentiality be maintained. Thus, reporting must follow predefined channels using standard procedures that guarantee that only authorized persons see the information. Such safeguards must be developed by local and national tuberculosis control programs to ensure the confidentiality of patient information.
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Research Needs
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As part of the process of developing the ISTC, several key areas that require additional research were identified (Table 6). Systematic reviews and research studies (some of which are underway currently) in these areas are critical to generate evidence to support rational and evidence-based care and control of tuberculosis. Research in these operational and clinical areas serves to complement ongoing efforts focused on developing new tools for tuberculosis control—new diagnostic tests,133 drugs,134 and vaccines.135
Key areas requiring additional research include:
  • Diagnosis and case finding
  • Treatment, monitoring, and support
  • Public health and operational research.
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Table 6   Priority areas for research and evaluation
Area of research
Specific research questions
Diagnosis and case finding
• What is the sensitivity and specificity of various thresholds for chronic cough (e.g. two versus three weeks) as a screening test to determine who should be evaluated for tuberculosis? How do local conditions such as the prevalence of tuberculosis, HIV infection, asthma, and chronic obstructive pulmonary disease (COPD) influence the threshold?
• What is the optimal diagnostic strategy/algorithm for establishing a diagnosis of tuberculosis in patients suspected of having the disease but who have negative sputum smears? Should the strategy be modified in patients with HIV infection?
• What is the optimal diagnostic algorithm for children with suspected tuberculosis?
• What is the role of therapeutic antibiotic trials in the diagnosis of smear-negative tuberculosis?
• What is the value and role of sputum concentration in improving the accuracy and yield of smear microscopy?
• What is the impact of bleach treatment of sputum on the accuracy and yield of sputum smear microscopy?
• What is the role, feasibility, and applicability of fluorescent microscopy in routine field conditions in areas of both high and low HIV prevalence?
• Is there a role for more intensive case finding in high-HIV-endemic settings?
• What is the contribution of routine use of culture in tuberculosis care and control in highprevalence areas?
• Is there a role for rapid culture methods in tuberculosis control programs?
• What factors lead to delays in establishing a diagnosis of tuberculosis?
• What is the impact of engaging former (or current) TB patients and/or patient organizations in active case finding?
• What is the role reporting by components of the healthcare system other than direct patient care providers?
Treatment, monitoring, and support
• What interventions are effective in improving patient (adults and children) adherence to antituberculosis therapy?
• What is the efficacy of direct observation of treatment (DOT) versus other measures to improve adherence to treatment?
• What is the role of fixed-dose combinations (FDCs) in improving adherence?
• What is the optimal duration of antituberculosis therapy for patients who are HIV-positive?
• What interventions help in reducing mortality among tuberculosis patients who have HIV infection?
• What is the effectiveness of standardized versus individualized treatment regimens in the management of mono-resistant and MDR tuberculosis?
• What is the relevance of second-line drug susceptibility test results in determining individualized retreatment regimens?
• What are the optimal drug doses and duration of treatment for children?
• What is the impact of engaging former (or current) TB patients or patient organizations in improving adherence?
Public health and operational research
• What is the effect of the DOTS strategy on tuberculosis transmission in populations with high rates of MDR tuberculosis?
• What is the impact of HIV infection on the effectiveness of DOTS programs?
• What interventions or measures are helpful in improving tuberculosis management practices in private practitioners?
• What is the impact of treatment of latent tuberculosis infection on tuberculosis burden in high-HIV-prevalence settings?
• What is the impact of engaging former (or current) patients and/or patient organizations in improving tuberculosis control programs in regions with insufficient human resources?
• What are the optimum models for integration of tuberculosis and HIV care?
47
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