Clinical and epidemiological aspects of smoking and tuberculosis:: a study of 13,038 cases

SETTING AND OBJECTIVE: Smoking habit and tuberculosis (TB) appear to have common epidemiological and clinical links. The present study was to evaluate risk factors in TB patients with and without a smoking habit. DESIGN: A cross-sectional observational study of cases (TB with smoking) and controls (TB without smoking) from the same registry. Data were retrieved from case notes and interviews of patients registered in the Tuberculosis Control Programme in Cataluna, Spain, between 1 January 1996 and 31 December 2002. Statistical analyses included univariatc and stepwise multiple logistic regression analyses. RESULTS : There were 13 038 recorded patients. Social factors associated with TB in smokers were mate sex (adjusted odds ratio [aOR] 2.2), age < 64 years, alcohol use > 30 g/day (aOR 7.4) and intravenous drug use (aOR 1.5). Smokers developed more pulmonary disease (aOR 1.5) and more cavitary lesions (aCIR 1.9), and were more likely to require hospitalisation (aOR 1.8) which was more protracted. Differences in mortality and delay in diagnosis did not reach statistical significance. CONCLUSIONS: Smoking leads to faster and more severe progression of TB. The cost of TB-related hospitalisation for smokers increases by approximately one million euros per year.