Prevalence and risk factors for bronchial asthma in Indian adults: a multicentre study.

Background: There is limited information on field epidemiology of bronchial asthma in Indian adults.
Objectives: To estimate prevalence of bronchial asthma in different regions of India and to define risk factors influencing disease prevalence.
Methods: A field study was conducted at Chandigarh, Delhi, Kanpur and Bangalore through a two stage stratified (urban/ rural) sampling and uniform methodology using a previously validated questionnaire. Asthma was diagnosed if the respondent answered affirmatively both to (a) whistling sound from chest, or chest tightness, or breathlessness in morning, and (b) having suffered from asthma, or having an attack of asthma in the past 12 months, or using bronchodilators. Besides demographic data, information on smoking habits, domestic cooking fuel used, atopic symptoms, and family history suggestive of asthma was also collected. Univariate and multivariate logistic regression modelling was performed to calculate odds ratio of various potential risk factors.
Results: Data from 73605 respondents (37682 men, 35923 women) were analysed. One or more respiratory symptoms were present in 4.3-10.5% subjects. Asthma was diagnosed in 2.28%, 1.69%, 2.05 and 3.47% respondents respectively at Chandigarh, Delhi, Kanpur and Bangalore, with overall prevalence of 2.38%. Female sex, advancing age, usual residence in urban area, lower socio-economic status, history suggestive of atopy, history of asthma in a first degree relative, and all forms of tobacco smoking were associated with significantly higher odds of having asthma.
Conclusion: Prevalence estimates of asthma in adults in this study, although lower than several previously reported figures, point to a high overall national burden of disease.