A Prospective Study of Passive Smoking and Coronary Heart Disease

BACKGROUND: Several epidemiological studies have suggested an association of passive smoking with coronary heart disease (CHD). However, few studies have taken account of exposure to passive smoking in the workplace. Additionally, several studies have been unable to control for the full range of potential confounding factors. We examined prospectively the relationship of passive smoking with risk of CHD in a cohort of women. METHODS AND RESULTS: The study was carried out in an ongoing prospective cohort of US female nurses, in whom we assessed exposure to passive smoking at home and at work as well as duration of years spent living with someone who smoked regularly. We studied 32046 women 36 to 61 years of age in 1982 who had never smoked and were free of diagnosed CHD, stroke, and cancer. During 10 years of follow-up (1982 to 1992), 152 incident cases of CHD (127 nonfatal myocardial infarction and 25 fatal CHD) occurred. Compared with women not exposed to passive smoking, the relative risks of total CHD-adjusted for a broad range of cardiovascular risk factors-were 1.58 (95% CI, 0.93 to 2.68) among those reporting occasional exposure and 1.91 (95% CI, 1.11 to 3.28) among women reporting regular exposure to passive smoking at home or work. There was no relation apparent between duration of living with a smoker and risk of CHD. CONCLUSIONS: Despite the fact that exposure to passive smoking was assessed by self-report and only at baseline (as well as other limitations), these data suggest that regular exposure to passive smoking at home or work increases the risk of CHD among nonsmoking women.