Epidemiology of asthma and associated factors in an urban Pakistani population: adult asthma study-Karachi

This study was conducted in order to determine the prevalence of asthma and associated risk factors in the adult population of Karachi, Pakistan. This multi-stage, cross-sectional survey was conducted from May 2014–August 2015; comprising 1629 adults in 75 randomly selected clusters in Karachi, Pakistan. Definitions included: ‘self-reported asthma’, ‘reversibility in FEV1’ and ‘respiratory symptoms and reversibility in FEV1’. Prevalence of asthma was 1.8% (self-reported) (95% CI: 1.0–2.6), 11.3% (reversibility in FEV1) (95% CI: 9.4–13.3) and 6.6% (symptoms and reversibility in FEV1) (95% CI: 5.1–8.1). Asthmatics were more likely to belong to the age group ≥38 years according to ‘reversibility in FEV1’ and ‘respiratory symptoms and reversibility in FEV1’ (AOR: 1.9, 95% CI: 1.2–3.3) and (AOR: 2.1, 95% CI: 1.1–4.2), respectively. Asthmatics were more likely to report history of allergies (AOR: 1.9, 95% CI: 1.2–2.9) and (AOR: 2.8, 95% CI: 1.7–4.8); and were exposed to environmental tobacco smoke (AOR: 1.6, 95% CI: 1.1–2.5) and (AOR: 1.9, 95% CI: 1.1–3.3) according to ‘reversibility in FEV1’ and ‘respiratory symptoms and reversibility in FEV1’, respectively. Asthmatics were more likely to report pack years of smoking ≥5 (AOR: 2.3, 95% CI: 1.1–4.7) according to ‘respiratory symptoms and reversibility in FEV1’. This study reports a high prevalence of asthma among Pakistani adults and calls for developing appropriate public health policies for prevention and control of asthma in the country. Further studies should be conducted to determine the national prevalence as well as follow-up studies to identify preventable causes for adult asthma.