Indian Study on Epidemiology of Asthma, Respiratory Symptoms and Chronic Bronchitis in Adults (INSEARCH)

Setting: Field sites in 12 districts in different parts of India.

Objective: To determine the nationwide population prevalence of and risk factors for asthma and chronic bronchitis (CB) in adults.

Design: A standardised validated questionnaire based on the International Union Against Tuberculosis and Lung Disease's 1984 questionnaire was used to assess asthma and CB prevalence. Multivariate logistic regression analyses were performed to determine the risk factor associations. Estimates standardised to the 2011 population projection estimates for India were used to calculate the national disease burden.

Results: A total of 85,105 men and 84,470 women from 12 urban and 11 rural sites were interviewed. One or more respiratory symptoms were present in 8.5% of individuals. The overall prevalence of asthma and CB was respectively 2.05% (adults aged ≥15 years) and 3.49% (adults aged ≥35 years). Advancing age, smoking, household environmental tobacco smoke exposure, asthma in a first-degree relative, and use of unclean cooking fuels were associated with increased odds of asthma and CB. The national burden of asthma and CB was estimated at respectively 17.23 and 14.84 million.

Conclusion: Asthma and CB in adults pose an enormous health care burden in India. Most of the associated risk factors are preventable.