Calculation of population attributable risk for bidi smoking and oral cancer in south Asia

Abstract

Background: Bidi smoking, which is widely prevalent in India and in other south Asian countries, increases the risk of oral cancer as observed in case-control studies and metaanalysis. However, population attributable risk percent (PAR%) has not been determined yet.

Materials and methods: Twelve case-control studies conducted in India, Pakistan, and Sri Lanka, which included information on bidi smoking and oral cancer, were analyzed countrywise to estimate PAR%.

Results: The cumulative cases and controls were 4778 and 6271, respectively, based on 10 case-control studies conducted in India. Among the cases, 49.1% were bidi smokers and 7.7% cigarette smokers, while they were 19.9% and 10.3%, respectively, among controls. Pooled odds ratio (OR) of bidi smoking for oral cancer was 3.3 [95% confidence interval (CI), 3.0-3.6] and 2.6 (95% CI 1.8-3.8), respectively, based on fixed- and random-effects model. Cigarette smoking, on the other hand, did not show any significant association. PAR% of bidi smoking for oral cancer ranged from 4.7% to 51.6% on individual study basis, while they were 31.4% and 24.1%, respectively, based on OR derived from fixed- and random-effects models. PAR% was 5.8% and 8.7% based on single study estimate from Pakistan and Sri Lanka, respectively.

Conclusions: Bidi smoking is considered to account for a sizeable number of oral cancers in south Asian countries, which implies that cessation programs should be formulated and implemented vigorously.