Secondhand Smoke Exposure Predicted COPD and Other Tobacco-Related Mortality in a 17-Year Cohort Study in China

Background Prospective evidence on the association between secondhand smoke (SHS) and COPD and ischemic stroke is scarce. Methods We prospectively examined the relationship between SHS and major tobacco-related deaths, particularly COPD and stroke, in 910 Chinese (439 men, 471 women) who never smoked from a 17-year follow-up study in Xi'an, China. SHS exposure was defined as exposure to another person's tobacco smoke at home or in the workplace. Results At baseline among the 910 subjects, 44.2% were exposed to SHS at home, 52.9% in the workplace, and 67.1% at home, work, or both. From March 1, 1994, to July 1, 2011, 249 (150 men, 99 women) died within 14,016 person-years. Those who were exposed to SHS had increased mortality due to coronary heart disease (adjusted relative risk [RR], 2.15; 95% CI, 1.00-4.61), ischemic stroke (RR, 2.88; 95% CI, 1.10-7.55), lung cancer (RR, 2.00; 95% CI, 0.62-6.40), COPD (RR, 2.30; 95% CI, 1.06-5.00), and all causes (RR, 1.72; 95% CI, 1.29-2.20), with significant dose-response relationships between cumulative SHS exposure at home and work and the increased risk of cause-specific and total mortality ( P for linear trend ranged from .045 to Conclusions This study shows dose-response relationships between SHS and major tobacco-related mortality and provides new evidence to support causation for COPD and ischemic stroke.