Assessing Tuberculosis among Smokers: Secondary Analysis of an Active Case Finding Project

Background: Previous case-control studies and a small number of cohort studies in high-risk populations have found an association between smoking and tuberculosis, but limited studies are available in the general population that predicts association of smoking and TB. Objectives: To investigate the association between smoking and tuberculosis in a cohort of a general population. Methods: Four districts of Punjab province (Lahore, Rawalpindi, Faisalabad and Islamabad) were randomly selected. In routine, household contact investigation is practiced by the National TB Control Programme. For two years from July 2013-June 2015, all people who were living within 50 metres from the household of smear positive TB patients were screened for tuberculosis. Those found presumptive TB were investigated through smear microscopy and those found smear negative; the Xpert MTB/RIF test was done. All the diagnosed TB patients were referred to nearest basic health unit for further treatment and care. Results: A total of 783,043 contacts were screened for tuberculosis, of whom 19,815 (2.53%) were smokers. Smoking was common among men, in diabetic & teenage, elderly age population and in household contact of smear positive TB patients. Smoking was associated with an increased risk of tuberculosis (odds ratio [OR], 2.43; 95% confidence interval, 2.27 - 2.60) in household contact of smear positive TB patients. The association was stronger among those greater than 45 years of age (OR, 11.09) than those between 25 - 44 years of age (OR, 5.83) and diabetic persons (OR, 2.0). Conclusions: Smoking was associated with a twofold increased risk of active tuberculosis in a cohort of general population.