Risk of Cardiovascular Disease Related to Smoking Is Greater Among Women With Sleep-Disordered Breathing.

STUDY OBJECTIVES: Although both sleep-disordered breathing (SDB) and smoking are associated with cardiovascular disease (CVD), the potential for an interactive effect on CVD risk has not been explored. Our objective was to determine if smoking-related risk for CVD rises with greater SDB severity.

METHODS: Polysomnography and smoking history were obtained in 3,852 men and women in the Sleep Heart Health Study without baseline CVD. Fine-Gray proportional hazard models accounting for competing risk were used to calculate risk of incident CVD associated with SDB severity (defined by clinical cutoffs of the apnea-hypopnea index), smoking status (never, former, and current) and their interaction adjusting for potential confounders.

RESULTS: Over a mean (standard deviation) follow-up period of 10.3 (3.4) years, there were 694 incident CVD events. We found a significant three-way interaction of sex, current smoking, and moderate to severe SDB ( P = .039) in the adjusted proportional hazards model. In adjusted analyses, women who were current smokers with moderate to severe SDB had a hazard ratio for incident CVD of 3.5 (95% confidence interval 1.6-8.0) relative to women who were nonsmokers without SDB. No such difference in CVD risk was observed in men or women of other strata of smoking and SDB.

CONCLUSIONS: In women, smoking-related risk for CVD is significantly higher among individuals with moderate to severe SDB.