Asthma in Children Meenu Singh
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Childhood Asthma: The Disease Burden1

Meenu Singh
A worldwide increase in the prevalence of asthma has been reported in recent years. With an increase in prevalence comes an increased burden of disease in terms of morbidity, mortality and compromised quality of life. The economic burden in terms of utilization of healthcare resources and limitation of the earning capacity of the individuals and families is an added problem. Various indicators such as disability adjusted life years and healthy life years have been used to define the economic burden. The data from Asian countries regarding these parameters in scarce, underlining the need of systematic studies in these countries, especially those that are resource poor. The present review highlights the varying prevalence of asthma in Asia and assesses the likely economic burden for the future.
It is estimated that as many as 300 million people of all ages and all ethnic backgrounds suffer from asthma and the burden of this disease to government, healthcare systems, families and patients is increasing worldwide.1
An estimation of the burden of asthma is needed to raise awareness among public health and government officials, healthcare workers and the general public towards the prevalence of asthma which is increasing. A management programme should be based on the best-available scientific 2evidence to provide effective medical care for asthma, tailored to local healthcare systems and resources. Asthma has become more common in both children and adults around the world in recent decades. The increased prevalence of asthma has been associated with an increase in atopic sensitization and other allergic disorders such as eczema and rhinitis. The rate of asthma increases as communities adopt Western life styles and become urbanized. With the projected increase in the urban proportion of the world's population from 45% to 59% in 2025, there is likely to be a marked increase in the number of individuals with asthma world-wide. It is estimated that there may be an additional 100 million people with asthma by 2025. The South Asian region of the world, with several developing countries, abounds in people with asthma who do not have access to basic asthma medications or medical care. Increasing the economic wealth and improving the distribution of resources between and within countries represent important priorities to enable the provision of the better health care. The burden of asthma in many countries is of sufficient magnitude to warrant its recognition as a priority disorder in government health strategies. The objectives of this article is to review the disease burden in countries in South Asian region in terms of prevalence, economic impact and effects on quality of life in order to prioritise resource allocation. Particular resources need to be provided to improve the care of disadvantaged groups with high morbidity, including certain racial groups, those who are poorly educated, live in large cities or are poor. Resources also need to be provided to address preventable factors that trigger exacerbations of asthma, such as air pollution.
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• Prevalence of Asthma In Asian Countries
The prevalence of asthma symptoms has been assessed by the International Study of Asthma and Allergies in Childhood (ISAAC) in several Asian Countries using a standardized questionnaire. The results of the ISAAC study suggest substantial worldwide variations in the prevalence of symptoms of allergic rhinoconjunctivitis, asthma ad atopic aczema. As part of the ISAAC study, prevalence surveys were conducted among representative samples of school children for locations in Europe, Asia, Africa, Australia and North and South America.2 In total 257,800 children aged 6–7 years from 91 centres in 38 countries and 463,801 children aged 13–14 years from 155 centres in 56 countries were surveyed. Written symptom questionnaires translated from English into the local language were self completed by the 13–14 year olds and completed by the parents of the 6–7 year olds. Within each age group the global pattern was broadly consistent across each of the symptom categories. The lowest prevalence of asthma was found in parts of Eastern Europe and South and Central Asia. In Asia, the prevalence ranged for 1.5% in Nepal to 6.2% in Hong Kong and the United Arab Emirates. High prevalence was reported from centres in several regions. These differences, if real, may offer important clues to environmental influences on allergy and underline the need for planned allocation and distribution of resources. Another survey estimated the prevalence of childhood asthma in urban areas in China in order to assess the influences of asthma on patients social lives and their families.3 A nationwide randomized survey, covering 43 cities in 31 provinces, on the prevalence of childhood asthma was carried 4out by the National Paediatric Cooperative Group of Asthma Research from June to October
2000 on a population of 437,873 children aged 0 to 14 years. Patients who had asthma, infantile asthma, cough variant asthma and questionnaire asthma were chosen as subjects. In total 10,065 subjects were screened as asthma associated by means of parental questionnaire, physical examination and case history review. Among them, 7401 (73.53%) children aged 3 years or more and 1109 (11.02%) infants and young children aged less than 3 years were diagnosed as asthma, 785 (7.80%) as cough variant asthma and 770 (7.65%) as questionable asthma. The average prevalence of accumulated asthma of the 0–14 year old asthma population (including asthma in older children and infants) was 1.97%. the male/female ration was 1.75:1.43 cities, with the highest rate in Chongquing (4.63%) and the lowest rate in Xining (0.25%). Overall, within (0.99%) an higher prevalence in south China (1.54%): the highest prevalence was seen in East china (2.37%), where 4670 (70%) children experienced asthma onset before 3 years of age. The current 2-year prevalence of Urban Chinese children was 1.54%. Thirty six of the 43 cities had received a similar asthma prevalence survey 10 years previously, which allowed a longitudinal comparison for 6370 patients (95.47%) family members work was affected because of their asthma attacks. One-third of the patients had used inhaled corticosteroids. In about two thirds of patients the diagnosis of asthma was correct. Only one third of patients with cough variant asthma were diagnosed correctly compared with their early diagnosis. Sixteen percent of patients had not been diagnosed as having asthma previously. Asthma prevalence has increased over the last 10 years, especially in the older age group. The survey inferred 5that there have been certain improvements in the accuracy of diagnosis and in the practice of steroid inhalation therapy in paediatricians in different cities.
The ISAAC study noted significant variation in prevalence in different parts of India with a range of 0.5–18% in 12-month prevalence of self - reported asthma symptoms from written questionnaire.4 A 20 to 60 fold difference in the prevalence of symptoms was found between various centres involved in this study. Although prevalence data of allergic disease in India in scarce, the little data that are available suggest that patterns differ in different areas. A study of 271 children from rural areas of Tamil Nadu reported a prevalence of breathing difficulty at any time in the past of 9%.5 In another study in rural areas of North India, the prevalence if chronic cough among children aged 1–15 years (n=2275) was 1.06% and two-thirds were due to asthma.6 Such variable patterns also exist across urban regions.7 Prevalence rates ranging from 1.9 to 15.7% have been reported.8 Such national variation, with almost 10–15 fold difference in the prevalence of allergic disorders, is probably unique to India. In a recently conducted study at our centre under the aegis of the Asthma Task Force of the Indian Council of Medical Research, a survey was conducted on 10,028 school children (10–15 yeas of age) belonging to 39 randomly selected schools for the diagnosis of asthma and other atopic disease in Chandigarh, India. A total of 536 children were found to have a current clinical diagnosis of asthma, allergic rhinitis or eczema. The prevalence of asthma was 3.3%. These findings were similar to the ISAAC surveys conducted at our centre.
Most urban areas in South Asia have high pollution indices, characterized by narrow streets, heavy traffic, 6smog, umplanned city architecture and the use of kerosene or wood as household fuel. However, some urban areas in South Asia are clean and modern, with concrete housing vehicle emission regulations and the use of smoke free household fuel. A study was conducted to compare the prevalence of wheeze in 13–14 year olds between two South Asia cities (Galle, Sri Lanka and Chandigarh, India) representing each of the above archetypes.9 The validated one page ISAAC questionnaire for 13–14 year olds was used for the study. Of 1814 distributed questionnaires. 1737 (95.8%) were completed correctly and returned. Crude prevalence rates and odds ratios (OR with 95% two sides confidence intervals (CI) for comparison of prevalence rates were calculated. The prevalence rate for wheezing in Galle (28.7%) was higher than that in Chandigarh (I 2.5%). The ORs for prevalence for Galle vs Chandigarh were: 2.3 (95% CI 1.8–2.9) for lifetime wheezing; 2.1 (95% CI 1.6–2.7) for wheezing in the previous year. 4.8 (95% CI 3.5–6.7) for exercise-related wheeze; and 1.7 (95% CI 1.2–2.3) for physician diagnosed wheeze, thus demonstrating significant differences in wheeze prevalence between the two cities (P<0.05). The numbers of 13–14 year olds experiencing less than 12 wheezing episodes per year or sleep disturbance due to wheeze of less than one night per week were also significantly higher for Galle than Chandigarh. Hence, a higher prevalence of wheeze was noticed in 13–14-year-old children living in an old-fashioned, congested city than in a clean, modern city in South Asia. Although reported countrywide prevalence of current asthma is lowest in Nepal, a high proportion of children in Nepal have 7allergic symptoms and positivity to skin tests. Two hundred and ninety-three ‘normal’ school children between 5 and 15 years of age living in the hills of Eastern Nepal were tested by the skin-prick method for sensitivity to six allergens: Dermatophagoides pteronyssinus, Aspergillus fumigatus, Cladosporium herbarum, Penicillium notaturn, mixed pollens and mixed threshings. These children were questioned and examined for symptoms and signs relating to allergic disease. Of these children, 20% were skin-prick positive to at least one of the allergens and 20% had symptoms of allergic disease. However, there was no relationship between the symptoms and the skin-prick test results.10 No relationship was found between the skin-prick test results and any of the following: the length of time a child was breast fed; the age of the child; and month of birth. Nineteen percent of boys and 11% of girls admitted to smoking cigarettes. Pakistan and Bangladesh have shown a relatively high prevalence of asthma. According to one report, up to 4% of children attending outpatient departments in Pakistan suffer from bronchial asthma. In the ISAAC survey, the reported prevalence of asthma in Bangladesh and Pakistan was 3.8% and 4.3%, respectively. Table 1 gives the prevalence of current asthma in various South Asian countries in relation to the population and population density of these countries to assess the burden of disease in tenns of the affected population and available resources.
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Table 1   Prevalence of clinical asthma in South Asian countries
Country
Population Thousand in year 2000
Population density/m2 in year 2000
Prevalence (%)
India
1 016 938
309
3.0
Pakistan
142 654
179
4.3
Bangladesh
137 952
958
3.8
Sri Lanka
18 595
283
5.5
China
1 275 215
133
2.1
 
• Morbidity and Health Care Utilisation
We compared the healthcare utilisation and work days lost for individuals with and without asthma in Chandigarh, India. Individual data on self-perceived asthma problems, self-reported utilisation of outpatient care and official data on inpatient care and work days lost were obtained from our Allergy and Asthma Clinic. Independent t-tests were performed to compare average differences in primary care visits, emergency room visits. days in hospital and work days lost for parents and patients. Compared with the general population individuals with asthma were found to make outpatient department visits and emergency visits and be hospitalised according to the following ratios: 3.1/1.0. 7.9/ 1.0 and 9.3/ 1.0/year, respectively. For work days lost, the ratio was 3.9/1.0. All differences were statistically significant. The self-reported data provided evidence of the burden of asthma to individuals and society. There is a great degree of variability in the healthcare standards in various private and government-funded facilities in India. General private practitioners deliver a large 9proportion of health care at a relatively higher cost. Hence generalisation of the estimation of expenditure is flawed due to a lack of uniformity in the cost structure of healthcare services.
An attempt was made to audit hospital admissions due to asthma in Pakistan.11 However, the authors concluded that the data available were inadequate and more documentation was required to improve the basic clinical management of individuals with asthma.
 
• Quality-of-life Issues
Asthma is known to reduce the quality of life of its sufferers. Most studies relating to quality of life come from the developed world. Appropriate measures to estimate quality of life in developing countries with diverse cultural beliefs, values and convictions are practically non-existent. Some attempts have been made in this direction but the wider applicability of these measures needs to be validated.12 Asthma education and quality of life in the community have been studied in the South Asian population residing in the UK.13 It was evaluated whether asthma morbidity in minority groups can be reduced by preventative healthcare measures delivered in the relevant ethnic dialects. Clinical outcomes and quality of life from a community-based project investigating white European (W/E) and Indian subcontinent (ISC) ethnic groups with asthma living in deprived inner city areas of Birmingham, UK were reported. Six hundred and eightynine asthmatic subjects (345 W/E, 344 ISC) of mean (SD) age 34.5 (15) years (range 11–59) and mean forced expiratory volume less than 80% predicted were interviewed in English Punjabi Hindi or Urdu. Subjects randomised to the active limb of a prospective, open, randomised, controlled, parallel group, 12-month follow-up study underwent 10individually based asthma education and optimisation of drug therapy with 4-monthly follow up (active intervention), Control groups were only seen at the beginning and end of the study. Urgent or emergency interactions with primary and secondary health care (clinical outcomes) and both cross-sectional and longitudinal data from an Asthma Quality of Life Questionnaire (AQLQ) were analysed. Clinical outcomes were available for 593 subjects. Fewer of the active intervention group consulted their general practitioner (GP) (41.8% vs 57.8%, OR 0.52, 95% CI 0.37-0.74) or were prescribed antibiotics (34.9% vs 5 1.2%, OR 0.51, 95% CI 0.36-0.72). However, by ethnicity, statistically significant changes only occurred in the W/E group with fewer also attending accident and emergency departments and requiring urgent home visits. Active intervention reduced the number of hospital admissions (10 vs 30), GP consultations (341 vs 476), prescriptions of rescue oral steroids (92 vs 177) and antibiotics (220 vs 340) but significant improvements by ethnicity only occurred in the active W/E group. AQLQ scores were negatively skewed to the higher values. Regression analysis showed that lower values were associated with ISC ethnicity. Longitudinal changes (for 522 subjects) in the mean AQLQ scores were small but statistically significant for both ethnic groups, with scores improving in the active group and worsening in the control group. It was concluded that active intervention only improved clinical outcomes in the W/E group, AQLQ scores, although lower in the ISC group, were improved by active intervention in both ethnic groups.
 
• Deaths
It is estimated that asthma accounts for about one in every 250 deaths worldwide. Comparison of asthma 11mortality between different countries has been made using asthma mortality rates in the 5–34-years age group because the diagnosis of asthma mortality is firmly established in this age group. Many deaths are preventable as they are due to suboptimal long-term medical care and delay in obtaining help during the final attack. Standardised data on deaths due to asthma are not available in most South Asian countries. We have had more than 7000 patients with asthma registered in our Allergy and Asthma Clinic since 1973 who come from different parts of the country: the majority come from the Northern region. Not a single death has been recorded in any of these patients who have had variable periods of follow-up.
 
• Disability Adjusted Life Years
Disability-adjusted life years (DALYs) is a measure of the burden of disease that assesses the years of healthy life lost due to disease or illness. DALYs combine information about morbidity and mortality in terms of healthy years lost. The calculation of disease-specific health loss in DALY s is the sum of years of life lost (YLLs) and years lived with disability (YLDs) weighted for severity. Each state of health is assigned a disability weighting by an expert panel on a scale from zero (perfect health) to one (death). To calculate the burden of a disease the disability weighting is multiplied by the number of years lived in that health state and is added to the number of years lost due to that disease. The number of DALYs lost due to asthma worldwide has been estimated to be about 15 million/year Worldwide, asthma accounts for around 1% of all DALYs lost, which reflects the high prevalence and severity of asthma. Asthma was the 25th leading cause of DALYs lost worldwide in 2001. The number 12of DALYs lost due to asthma is similar to that for diabetes, liver cirrhosis or schizophrenia. The burden of disease in terms of DALYs has not been calculated for most Asian countries: however some indirect attempts have been made. While developing a draft measure of the burden of diseases in Sri Lanka using DALYS.14 computation was done for 100 disease categories identified to reflect the disease pattern in Sri Lanka. Factors that were considered for the calculation of DALYs were incidence, degree of disability, duration of illness and age at onset. Injuries, ischaemlc heart disease, asthma, disease of the pulmonary circulation and burns contribute to 55% of the burden of disease in Sri Lanka. The highest burden was due to non-communicable diseases. as their duration and degree of disability are high. YLDs contribute nearly two-thirds of the DALYs worldwide and are particularly important in developing countries where infant and child mortality is still high. These were estimated for India under the global burden of disease study in 1990. A study estimated different causes of YLDs in rural areas of India. Pneumonia was the top cause responsible for YLDs; heart attacks bronchitis and asthma had lower YLDs.15 For children living in developing countries. A study has identified the major causes of ill health that are Inadequately covered by established health programmes.16 Injuries and non-communicable diseases notably asthma, epilepsy, dental caries, diabetes mellitus and rheumatic heart disease have been identified as growing in significance. In countries where resources are scarce, it is to be expected that increasing importance will be attached to the development and implementation of measures against these problems. This study evaluated the major causes of ill health that are not covered by global health programmes 13among children in developing countries. Assessments were based on a set of death and disability estimates. Causes of death were classified as: (1) infectious, maternal, perinatal and nutritional conditions: (2) non-communicable diseases: or (3) injuries. DALYs were used in estimates of disease burden. Childhood disease burden In 1990 among regions, age groups and sex were compared using DALYs/1000 population and presented in table form. Among childhood disease burdens infectious, perinatal and nutritional disorders ranked first (72%), followed by non-communicable diseases including asthma (15%) and injuries (13%); these values are significantly higher in developing countries than in developed regions. This study has special relevance for South Asia where programmes directed against infectious, nutritional and perinatal disorders need to be applied to the control of non-communicable diseases. The importance of community involvement, family education and social marketing needs emphasising in the formulation and implementation of these control measures. In the last decade a number of quantitative epidemiological studies of specific diseases have been undertaken in developing countries. This allows for the first time, estimation of the total burden of disease (mortality and morbidity) attributable to use of solid fuels in adult women and young children who jointly receive the highest exposures because of their household roles. Few such studies are available to date for adult men or children over 5 years of age. A paper has evaluated the existing epidemiological studies and applied the resulting risks to Indian households dependent on such fuels (>75%).17 Allowance was made for the existence or improved stoves with chimneys and other factors that may lower exposure. Attributable risks were calculated in 14reference to the demographic conditions and patterns of each disease in India. Sufficient evidence was available to estimate risks most confidently for acute respiratory infections chronic obstructive pulmonary disease and lung cancer. Estimates for tuberculosis asthma and blindness were of intermediate confidence. Estimates for heart disease had the lowest confidence. Insufficient quantitative evidence is currently available to estimate the impact on adverse pregnancy outcomes (e.g. low birth weight and stillbirth). The resulting conservative estimates indicate that 400,000–550,000 premature deaths can be attributed annually to use of biomass fuels in these population groups due to respiratory diseases including asthma.
 
• Economic Costs
Patients with difficult-to-treat or suboptimally controlled asthma consume a disproportionate share of asthma healthcare resources.18 Treatment strategies that minimise exacerbations may decrease the need for unscheduled medical services reduce emergency department visits and minimize asthma-related hospitalisations. Poor control of symptoms is a major issue that can result in adverse clinical and economic outcomes. Prescribing costs are the most obvious visible expense in asthma care but these are only the tip of the iceberg. We need to take all factors into account when considering the overall cost of asthma treatments and recognise that treatment which results in better asthma control may reduce both direct and indirect costs. To assess this accurately health economic evaluations need to be undertaken in relevant settings on representative populations. They need to use appropriate measures of asthma outcome. Drug related costs need to take into account savings 15made by decreased costs of other prescribed medication and patient factors. We need information that is applicable to the types of patients we see in the real world to make proper cost analyses. Such information can come from good-quality randomised trials, retrospective analysis of research databases and observational studies, or using primary care clinical and prescribing databases.19 Asthma self-management training can significantly affect the health status and resource use of patients with chronic asthma.20 A randomised controlled trial on chronic asthmatic patients was conducted in a tertiary care centre in India. The intervention group (153 patients) received four training sessions in addition to the regular care provided to the control group (150 patients). Health status and resource use were measured at baseline and over a 1-year follow-up period. The intervention group had significantly better health status (measured by breathing ability) fewer productive days lost and lower resource use (hospitalisations and emergency room visits) than the control group. Total annual costs (direct and indirect) were also lower, although physician costs were not included in the assessment. It was concluded that the incorporation of asthma self-management training as part of clinical management of asthma can result in improvements in health status and reductions in hospital use.
 
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