Cardiovascular Mortality in Women With Obstructive Sleep Apnea With or Without Continuous Positive Airway Pressure Treatment: A Cohort Study
Is obstructive sleep apnea (OSA) a risk factor for cardiovascular death in women, and does continuous positive airway pressure (CPAP) treatment reduce mortality risk?
This was a prospective observational cohort study, which enrolled women from two sleep clinics in Spain. All women were referred for suspected OSA between 1998 and 2007, and received a diagnostic sleep study. Women with an apnea–hypopnea index (AHI) less than 10 were the control group. OSA was diagnosed when the AHI was 10 or higher (classified as mild to moderate [AHI of 10-29] or severe [AHI ≥30]). Women were classified as treated if they wore their CPAP ≥4 hours per day, and untreated if CPAP was worn <4 hours per day (or not prescribed). Participants were followed until December 2009. The primary outcome of interest was cardiovascular mortality.
A total of 1,116 women were included in the study (median follow-up, 72 months [interquartile range, 52-88 months]). The control group had a lower cardiovascular mortality rate (0.28 per 100 person-years, 95% confidence interval [CI], 0.10-0.91) than the untreated groups with mild to moderate OSA (0.94 per 100 person-years, CI, 0.10-2.40; p = 0.034) or severe OSA (3.71 per 100 person-years, CI, 0.09-7.50; p < 0.001). Compared with the control group, the fully adjusted hazard ratios for cardiovascular mortality were 3.50 (CI, 1.23-9.98) for the untreated, severe OSA group; 0.55 (CI, 0.17-1.74) for the CPAP-treated, severe OSA group; 1.60 (CI, 0.52-4.90) for the untreated, mild to moderate OSA group; and 0.19 (CI, 0.02-1.67) for the CPAP-treated, mild to moderate OSA group.
The investigators concluded that severe OSA is associated with increased risk of cardiovascular death in women, and adequate CPAP treatment may reduce this risk.
OSA is associated with both cardiovascular risk factors and cardiovascular disease mortality in men. This study suggests the risk of cardiovascular disease mortality associated with OSA is also present in women. A randomized controlled trial examining treatment of OSA in relation to cardiovascular disease risk among women would be recommended, based on these findings.
Keywords: Spain, Continuous Positive Airway Pressure, Cardiovascular Diseases, Sleep Apnea Syndromes
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