Background: Obstructive sleep apnea (OSA) is a risk factor for cardiovascular death in men, but whether it is also a risk factor in women is unknown.
Objective: To investigate whether OSA is a risk factor for cardiovascular death in women and assess whether continuous positive airway pressure (CPAP) treatment is associated with a change in risk.
Design: Prospective, observational cohort study.
Setting: 2 sleep clinics in Spain.
Patients: All women consecutively referred for suspected OSA between 1998 and 2007.
Intervention: Every woman had a diagnostic sleep study. Women with an apnea–hypopnea index (AHI) less than 10 were the control group. Obstructive sleep apnea was diagnosed when the AHI was 10 or higher (classified as mild to moderate [AHI of 10 to 29] or severe [AHI ≥30]). Patients with OSA were classified as CPAP-treated (adherence ≥4 hours per day) or untreated (adherence <4 hours per day or not prescribed). Participants were followed until December 2009.
Measurements: The end point was cardiovascular death.
Results: 1116 women were studied (median follow-up, 72 months [interquartile range, 52 to 88 months]). The control group had a lower cardiovascular mortality rate (0.28 per 100 person-years [95% CI, 0.10 to 0.91]) than the untreated groups with mild to moderate OSA (0.94 per 100 person-years [CI, 0.10 to 2.40]; P = 0.034) or severe OSA (3.71 per 100 person-years [CI, 0.09 to 7.50]; P < 0.001). Compared with the control group, the fully adjusted hazard ratios for cardiovascular mortality were 3.50 (CI, 1.23 to 9.98) for the untreated, severe OSA group; 0.55 (CI, 0.17 to 1.74) for the CPAP-treated, severe OSA group; 1.60 (CI, 0.52 to 4.90) for the untreated, mild to moderate OSA group; and 0.19 (CI, 0.02 to 1.67) for the CPAP-treated, mild to moderate OSA group.
Limitation: The study was observational and not randomized, and OSA was diagnosed by 2 different methods.
Conclusion: Severe OSA is associated with cardiovascular death in women, and adequate CPAP treatment may reduce this risk.
Primary Funding Source: None.