title: Directly measured secondhand smoke exposure and COPD health outcomes.
abstract: BACKGROUND
  Although personal cigarette smoking is the most important cause and modulator of chronic obstructive pulmonary disease (COPD), secondhand smoke (SHS) exposure could influence the course of the disease. Despite the importance of this question, the impact of SHS exposure on COPD health outcomes remains unknown.
  
  
  METHODS
  We used data from two waves of a population-based multiwave U.S. cohort study of adults with COPD. 77 non-smoking respondents with a diagnosis of COPD completed direct SHS monitoring based on urine cotinine and a personal badge that measures nicotine. We evaluated the longitudinal impact of SHS exposure on validated measures of COPD severity, physical health status, quality of life (QOL), and dyspnea measured at one year follow-up.
  
  
  RESULTS
  The highest level of SHS exposure, as measured by urine cotinine, was cross-sectionally associated with poorer COPD severity (mean score increment 4.7 pts; 95% CI 0.6 to 8.9) and dyspnea (1.0 pts; 95% CI 0.4 to 1.7) after controlling for covariates. In longitudinal analysis, the highest level of baseline cotinine was associated with worse COPD severity (4.7 points; 95% CI -0.1 to 9.4; p = 0.054), disease-specific QOL (2.9 pts; -0.16 to 5.9; p = 0.063), and dyspnea (0.9 pts; 95% CI 0.2 to 1.6 pts; p < 0.05), although the confidence intervals did not always exclude the no effect level.
  
  
  CONCLUSIONS
  Directly measured SHS exposure appears to adversely influence health outcomes in COPD, independent of personal smoking. Because SHS is a modifiable risk factor, clinicians should assess SHS exposure in their patients and counsel its avoidance. In public health terms, the effects of SHS exposure on this vulnerable subpopulation provide a further rationale for laws prohibiting public smoking.
authors.affiliation: Department of Medicine, University of California, San Francisco, UCSF Box 0924, San Francisco, CA 94113-0924, USA. mark.eisner@ucsf.edu
authors.forename: Mark D
authors.initials: MD
authors.lastname: Eisner
authors.forename: John
authors.initials: J
authors.lastname: Balmes
authors.forename: Edward H
authors.initials: EH
authors.lastname: Yelin
authors.forename: Patricia P
authors.initials: PP
authors.lastname: Katz
authors.forename: S Katherine
authors.initials: SK
authors.lastname: Hammond
authors.forename: Neal
authors.initials: N
authors.lastname: Benowitz
authors.forename: Paul D
authors.initials: PD
authors.lastname: Blanc
mesh_terms: D000368:Aged; D003367:Cotinine / Q000652:urine; D004417:Dyspnea / Q000209:etiology / Q000503:physiopathology; D005260:Female; D005373:Film Dosimetry; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D009538:Nicotine / Q000032:analysis; D011379:Prognosis; D029424:Pulmonary Disease, Chronic Obstructive / Q000150:complications* / Q000503:physiopathology* / Q000652:urine; D011788:Quality of Life; D012307:Risk Factors; D012720:Severity of Illness Index; D014028:Tobacco Smoke Pollution / Q000009:adverse effects*
chemical_list: D014028:Tobacco Smoke Pollution; D009538:Nicotine; D003367:Cotinine