PURPOSE: Active tobacco smoking predisposes to various infections amongst which pulmonary tuberculosis (PTB) is an important infection. The same may be true for environmental tobacco smoke (ETS).This study was conducted to assess the causal relationship, and impact of active smoking and ETS, on the severity of PTB.
METHODS: Patients with newly diagnosed PTB, attending the out-patient department of this institute, were compared with double the number of age and sex-matched healthy volunteers. Detailed information on clinical symptoms, demographic variables, smoking habits and contact with PTB was collected using a standard questionnaire. Data was analyzed between smokers and non-smokers, and between non-smokers exposed to ETS and those without.
RESULTS: There were 125 cases (94 males) and 250 controls (188 males) with a mean (SD) age of 37.2 (12.1) years. Most patients presented with a moderate to advanced radiological stage and 93.6% had a poor functional (MRC scale ≥3) status. There were significantly more smokers among cases than controls (51.2% vs. 35.6%). There was no difference in the number of non-smokers exposed to ETS among cases and controls (18% vs. 19.3%) and the cumulative ETS exposure (mean 399.5 [SD, 296.6] hours/day/year among cases and 471.1 [432.7] among controls). Both patients with active smoking and non-smokers exposed to ETS had more severe disease both clinically and radiologically but only the former had higher odds for developing PTB after adjusting for age, gender, religion, education and previous exposure to patients with PTB, but not the ETS group (AOR 2.37, 95% CI 1.29-4.35 and AOR 0.92, 95% CI 0.43-1.98 respectively).
CONCLUSION: Active smoking is an important risk factor for development of PTB and for having a severe disease. Exposure to ETS amongst non-smokers is also associated with disease severity, although the causal relationship of developing PTB was not significant in this study.
CLINICAL IMPLICATIONS: Both active and passive smoking may be associated with more severe forms of PTB. More studies are required to prove the role of ETS in causation of PTB.
DISCLOSURE: Ritesh Agarwal, None.