title: Exposure to secondhand smoke and risk of tuberculosis: prospective cohort study.
abstract: BACKGROUND
  Prospective evidence on the association between secondhand-smoke exposure and tuberculosis is limited.
  
  
  METHODS
  We included 23,827 never smokers from two rounds (2001 and 2005) of Taiwan National Health Interview Survey. Information on exposure to secondhand smoke at home as well as other sociodemographic and behavioral factors was collected through in-person interview. The participants were prospectively followed for incidence of tuberculosis through cross-matching the survey database to the national tuberculosis registry of Taiwan.
  
  
  RESULTS
  A total of 85 cases of active tuberculosis were identified after a median follow-up of 7.0 years. The prevalence of exposure to secondhand smoke at home was 41.8% in the study population. In the multivariable Cox proportional hazards analysis, secondhand smoke was not associated with active tuberculosis (adjusted hazard ratio [HR], 1.03; 95% CI, 0.64 to 1.64). In the subgroup analysis, the association between secondhand smoke and tuberculosis decreased with increasing age; the adjusted HR for those <18, > = 18 and <40, > = 40 and <60, and > = 60 years old was 8.48 (0.77 to 93.56), 2.29 (0.75 to 7.01), 1.33 (0.58 to 3.01), and 0.66 (0.35 to 1.23) respectively. Results from extensive sensitivity analyses suggested that potential misclassification of secondhand-smoke exposure would not substantially affect the observed associations.
  
  
  CONCLUSIONS
  The results from this prospective cohort study did not support an overall association between secondhand smoke and tuberculosis. However, the finding that adolescents might be particularly susceptible to secondhand smoke's effect warrants further investigation.
authors.affiliation: Institute of Epidemiology and Preventive Medicine, National Taiwan University, Taipei, Taiwan.
authors.forename: Hsien-Ho
authors.initials: HH
authors.lastname: Lin
authors.forename: Yi-Ting
authors.initials: YT
authors.lastname: Chiang
authors.forename: Jen-Hsiang
authors.initials: JH
authors.lastname: Chuang
authors.forename: Shiang-Lin
authors.initials: SL
authors.lastname: Yang
authors.forename: Hsing-Yi
authors.initials: HY
authors.lastname: Chang
authors.forename: Majid
authors.initials: M
authors.lastname: Ezzati
authors.forename: Megan
authors.initials: M
authors.lastname: Murray
mesh_terms: D000293:Adolescent; D000328:Adult; D000367:Age Factors; D005260:Female; D006306:Health Surveys; D006801:Humans; D015994:Incidence; D008297:Male; D008875:Middle Aged; D016016:Proportional Hazards Models; D011446:Prospective Studies; D012042:Registries; D012306:Risk; D012307:Risk Factors; D013624:Taiwan / Q000453:epidemiology; D014028:Tobacco Smoke Pollution; D014397:Tuberculosis, Pulmonary / Q000453:epidemiology
chemical_list: D014028:Tobacco Smoke Pollution