Comparison of different chronic respiratory diseases in terms of cigarette smoking: A hospital-based case control study on population of Bangladesh

Cigarette smoking is considered as one of the main factors of developing chronic respiratory diseases (CRDs), but very few studies had been performed showing comparative association between different CRDs and cigarette smoking. This study attempts to determine and compare the association of cigarette smoking with different CRDs including chronic obstructive pulmonary disease (COPD), chronic bronchitis (CB), and asthma altogether in the context of Bangladesh. This case-control study was conducted among 406 subjects, where 297 were cases of chronic respiratory illness and 109 were controls. The diagnosis of each respiratory diseases (either asthma or CB or COPD) was confirmed by registered physicians. Of 98 COPD patients, 100 CB patients, 99 asthma patients and 109 controls, current smokers were found as 67.3%, 58%, 41.4%, and 33.9%, respectively. Current smokers with Brinkman Index (BI)≥ 400 were 43.9%, 39.7%, 26.9% and 8.2% for COPD, CB, asthma, and control group, sequentially. Regarding unadjusted association between cigarette smoking and different CRDs, current smokers with BI≥ 400 had 4.55, 21.75 and 13.14 times significantly higher chances of developing asthma, COPD and CB respectively than non-smokers. Logistic analysis revealed that after adjustment with age, body mass index (BMI) and gender, current smokers with BI≥ 400 had 6.01, 15.63 and 33.47 times more likelihood of developing asthma, CB, and COPD respectively than non-smokers; and these findings were significant as well. Thus, it can be concluded that cigarette smoking affected COPD more pronouncedly followed by CB and asthma among the study population.