title: Passive smoking and chronic obstructive pulmonary disease mortality: findings from the Japan collaborative cohort study.
abstract: OBJECTIVE
  To elucidate the association between passive smoking at home and chronic obstructive pulmonary disease (COPD) mortality via a large-scale nationwide cohort study in Japan.
  
  
  METHODS
  Never smokers (n = 34,604) aged 40-79 years at baseline (1988-1990; 4884 men, 29,720 women) were included in the analysis. Passive smoking at home was measured based on self-reported frequency of weekly exposure to passive smoking at home. An inverse probability of treatment-weighted competing risk model was used to calculate the hazard ratio (HR) and 95% confidence interval (CI) for COPD mortality.
  
  
  RESULTS
  During a median follow-up of 16.4 years, 33 participants (10 men, 23 women) died of COPD. The HR for participants exposed to passive smoking at home ≤4 days per week or those who had almost daily exposure to passive smoking at home had a significantly increased risk of COPD mortality (HR 2.40, 95% CI 1.39-4.15, HR 2.88, 95% CI 1.68-4.93, respectively).
  
  
  CONCLUSIONS
  The present findings suggest that avoiding passive smoking at home may be beneficial for preventing death due to COPD among never smokers.
authors.affiliation: Department of Public Health, Hokkaido University Graduate School of Medicine, N15 W7, Kita-ku, Sapporo, Hokkaido, 060-0812, Japan.
authors.forename: Shigekazu
authors.initials: S
authors.lastname: Ukawa
authors.affiliation: Department of Public Health, Hokkaido University Graduate School of Medicine, N15 W7, Kita-ku, Sapporo, Hokkaido, 060-0812, Japan. tamaa@med.hokudai.ac.jp.
authors.forename: Akiko
authors.initials: A
authors.lastname: Tamakoshi
authors.affiliation: Department of Public Health, Fujita Health University, Aichi, Japan.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Yatsuya
authors.affiliation: Department of Public Health Medicine, Faculty of Medicine, University of Tsukuba, Ibaraki, Japan.
authors.forename: Kazumasa
authors.initials: K
authors.lastname: Yamagishi
authors.affiliation: Center for Advanced Medicine and Clinical Research, Nagoya University Hospital, Aichi, Japan.
authors.forename: Masahiko
authors.initials: M
authors.lastname: Ando
authors.affiliation: Public Health, Department of Social and Environmental Medicine, Osaka University Graduate School of Medicine, Osaka, Japan.
authors.forename: Hiroyasu
authors.initials: H
authors.lastname: Iso
mesh_terms: D015331:Cohort Studies; D004781:Environmental Exposure / Q000009:adverse effects; D005260:Female; D006801:Humans; D007564:Japan / Q000453:epidemiology; D008297:Male; D008875:Middle Aged; D029424:Pulmonary Disease, Chronic Obstructive / Q000175:diagnosis / Q000453:epidemiology* / Q000209:etiology / Q000401:mortality*; D012307:Risk Factors; D011795:Surveys and Questionnaires; D014028:Tobacco Smoke Pollution / Q000009:adverse effects*
chemical_list: D014028:Tobacco Smoke Pollution
keywords: Chronic obstructive pulmonary disease; Cohort study; Mortality; Passive; Smoking