Continuous positive airway pressure (CPAP) improves cardiovascular outcomes in high-risk obstructive sleep apnea (OSA) but may increase cardiovascular risk in low-risk OSA, according to a multi-trial analysis published Aug. 5 in EHJ.

Ali Azarbarzin, PhD, et al., conducted a post hoc analysis of the ISAACC, RICCADSA and SAVE randomized trials. Participants were eligible if they had an apnea-hypopnea index ≥15 events/hr or equivalent 4% oxygen desaturation index of ≥12 events/hr. Of the 3,549 participants (median age 61; 18% women), 1,832 were identified as high-risk – defined as augmented OSA-related pulse rate acceleration (>9.4 beats/min) and/or hypoxemia (>87.1% min/hr).

Results showed at a median follow-up of 3.1 years, 17% of those randomized to CPAP reached the primary endpoint of major adverse cardiovascular and cerebrovascular events (including cardiovascular mortality, myocardial infarction and stroke), vs. 16% with usual care. Within the CPAP and usual care arms, events occurred in 15% vs. 18% and 18% vs. 15% of the high-risk and low-risk subgroups, respectively. In addition, the treatment effect was found to be stronger in high-risk participants, with the differential effect stronger only in those without excessive sleepiness or increased blood pressure.

"Our findings provide a much-needed basis for recognizing favorable long-term cardiovascular responses to CPAP for future prospective evaluations," the authors conclude.

In an accompanying editorial comment, Andrea Natale, MD, FACC, and Sanghamitra Mohanty, MD, caution that the study had several limitations, including that the study population was predominantly men. They add that poor therapeutic compliance, a participant population excluded for severe daytime sleepiness and unique definitions of "high-risk" and "low-risk" populations may have limited the generalizability of the findings.