Smoking adversely affects treatment response, outcome and relapse in tuberculosis.

The impact of smoking on tuberculosis outcome was evaluated in a territory-wide treatment programme. 16,345 consecutive patients undergoing chemotherapy for active tuberculosis in government chest clinics in Hong Kong from 2001 to 2003 were followed up prospectively for 2 years for treatment outcome and subsequently tracked through the territory-wide tuberculosis notification registry for relapse until the end of 2012. Smoking was associated with more extensive lung disease, lung cavitation and positive sputum smear and culture at the baseline. In both current smokers and ex-smokers, sputum smears and cultures were significantly more likely to remain positive after 2 months of treatment. Both categories of smokers were significantly less likely to achieve cure or treatment completion within 2 years. Overall, 16.7% of unsuccessful treatment outcomes were attributable to smoking, with the key contributor being default in current smokers and death in ex-smokers. Among successful treatment completers, there was a clear gradient (hazard ratios of 1.00, 1.33 and 1.63) of relapse risk from never-smokers to ex-smokers and current smokers, with an overall population attributable risk of 19.4% (current smokers: 12.2%; ex-smokers: 7.2%). Smoking adversely affects baseline disease severity, bacteriological response, treatment outcome and relapse in tuberculosis. Smoking cessation likely reduces relapse and secondary transmission.

Mesothelioma and lung cancer mortality: a historical cohort study among asbestosis workers in Hong Kong.

OBJECTIVES: To investigate the mortality pattern among a cohort of workers with asbestosis in Hong Kong, with special emphases on mesothelioma and lung cancer. METHODS: All 124 male workers with confirmed asbestosis in Hong Kong during 1981-2008 were followed up to December 31, 2008 to ascertain the vital status and causes of death. Standardized mortality ratio (SMR) for each underlying cause of death was calculated by using person-year method. Axelson's indirect method was applied to adjust for the potential confounding effect of cigarette smoking. RESULTS: A total of 86 deaths were observed after 432.8 person-years of observations. The SMR for overall mortality (6.06, 95% CI: 4.90-7.51) increased significantly. The elevated risk of deaths from all cancers (7.53, 95% CI: 5.38-10.25) was mainly resulted from a significantly excess risk from lung cancer (SMR=7.91, 95% CI: 4.32-13.29, 14 deaths) and mesothelioma (SMR=6013.63, 95% CI: 3505.95-9621.81, 17 deaths). The SMR for lung cancer retained statistically significant after adjustment of smoking. An increased smoking adjusted SMR was also suggested for all heart diseases (2.32, 95% CI: 0.93-4.79, 7 deaths) and acute myocardial infarction (3.10, 95% CI: 0.84-7.94, 4 deaths), though the statistical significance was borderline. We found a positive association with net years of exposure to asbestos for mesothelioma and lung cancer. CONCLUSIONS: Our study provided further evidence on the carcinogenesis of asbestos/asbestosis with the risk of deaths from lung cancer and mesothelioma. This study also provided a preliminary support for a possible link between asbestosis and heart disease, but power is limited.