title: Smoking adversely affects treatment response, outcome and relapse in tuberculosis.
abstract: 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.
authors.affiliation: TB and Chest Service, Dept of Health, Hong Kong, China.
authors.forename: Chi C
authors.initials: CC
authors.lastname: Leung
authors.affiliation: Stanley Ho Centre for Emerging Infectious Diseases, The Chinese University of Hong Kong, Hong Kong, China.
authors.forename: Wing W
authors.initials: WW
authors.lastname: Yew
authors.affiliation: TB and Chest Service, Dept of Health, Hong Kong, China.
authors.forename: Chi K
authors.initials: CK
authors.lastname: Chan
authors.affiliation: TB and Chest Service, Dept of Health, Hong Kong, China.
authors.forename: Kwok C
authors.initials: KC
authors.lastname: Chang
authors.affiliation: TB and Chest Service, Dept of Health, Hong Kong, China.
authors.forename: Wing S
authors.initials: WS
authors.lastname: Law
authors.affiliation: TB and Chest Service, Dept of Health, Hong Kong, China.
authors.forename: Shuk N
authors.initials: SN
authors.lastname: Lee
authors.affiliation: TB and Chest Service, Dept of Health, Hong Kong, China.
authors.forename: Lai B
authors.initials: LB
authors.lastname: Tai
authors.affiliation: TB and Chest Service, Dept of Health, Hong Kong, China.
authors.forename: Eric C C
authors.initials: EC
authors.lastname: Leung
authors.affiliation: TB and Chest Service, Dept of Health, Hong Kong, China.
authors.forename: Ronald K F
authors.initials: RK
authors.lastname: Au
authors.affiliation: TB and Chest Service, Dept of Health, Hong Kong, China.
authors.forename: Shan S
authors.initials: SS
authors.lastname: Huang
authors.affiliation: TB and Chest Service, Dept of Health, Hong Kong, China.
authors.forename: Cheuk M
authors.initials: CM
authors.lastname: Tam
mesh_terms: D000328:Adult; D000368:Aged; D000995:Antitubercular Agents / Q000627:therapeutic use*; D005260:Female; D005500:Follow-Up Studies; D006723:Hong Kong / Q000453:epidemiology; D006801:Humans; D015994:Incidence; D008297:Male; D008875:Middle Aged; D009169:Mycobacterium tuberculosis / Q000187:drug effects / Q000302:isolation & purification; D012008:Recurrence; D012042:Registries; D012307:Risk Factors; D012907:Smoking / Q000009:adverse effects / Q000453:epidemiology; D016540:Smoking Cessation / Q000706:statistics & numerical data; D013183:Sputum / Q000382:microbiology*; D016896:Treatment Outcome; D014397:Tuberculosis, Pulmonary / Q000150:complications / Q000188:drug therapy / Q000453:epidemiology
chemical_list: D000995:Antitubercular Agents