CPAP Adherence Lowers Risk for Cardiovascular Events in Patients With OSA

Among patients with obstructive sleep apnea (OSA) and cardiovascular disease (CVD), good adherence of continuous positive airway pressure (CPAP; at least 4 hours a day) is associated with a lower risk for major adverse cardiac and cerebrovascular events (MACCEs), according to study findings published in The Journal of the American Medical Association. 

Previous research on the effect of CPAP on secondary CVD prevention remains unclear. Researchers conducted an individual participant data (IPD) meta-analysis to determine the effect of CPAP in patients with OSA and the risk of adverse CV events.

The researchers collected data on randomized clinical trials (RCTs) from:

• PubMed (MEDLINE),
• EMBASE,
• Current Controlled Trials: metaRegister of Controlled Trials,
• ISRCTN Registry,
• European Union clinical trials database,
• CENTRAL (Cochrane Central Register of Controlled Trials), and
• ClinicalTrials.gov. 

The primary outcome was the composite of the first MACCE or death due to CV complications, myocardial infarction (MI), stroke, revascularization, and hospitalization due to heart failure, unstable angina, or transient ischemic attack. 

Of the 1824 studies screened for inclusion, the researchers included 3 RCTs with 4186 participants (mean age, 61.2; 82.1% men) in the final analysis. All studies were open-label, parallel RCTs and the average follow-up period ranged from 34 to 52 months. 

All studies used sleep apnea testing to determine eligibility and the Epworth Sleepiness Scale score ranged between 5.3 and 7.4 points. 

A total of 2097 participants included in the IPD meta-analysis were randomly assigned to undergo CPAP treatment and 2089 were randomly assigned to receive no CPAP. The mean apnea-hypopnea index (AHI) was 31.2 events per hour. OSA was defined as an oxygen desaturation index of 12 events or more per hour or an AI of 15 events or more per hour.

Of the 4186 participants, 691 experienced MACCEs (16.5%), with 349 in the CPAP group and 342 in the no CPAP group.

The intention-to-treat (ITT) analysis revealed there were no significant differences in MACCEs between participants who did and did not have CPAP (1-stage Hazard Ratio [HR] of CPAP, 1.01; 95% CI, 0.87-1.17; P =.94). The 2-stage analysis confirmed findings from the 1-stage analysis. 

The CPAP adherence decreased over the first year and was maintained throughout the rest of the follow-up period. Among participants using CPAP, 38.5% had good adherence (4 hours or more a day) and the median duration of adherence was 3.03 hours per day (interquartile ratio [IQR], 0.75-5.10). 

After adjusting for time and confounding factors, the researchers identified a decreased MACCE risk among participants with good CPAP adherence (HR, 0.69; 95% CI, 0.52- 0.92; P =.01). In a sensitivity analysis, the researchers found that these patients also experienced a significant risk reduction for MACCE compared with those who did not meet criteria for good adherence (HR, 0.55; P =.005).

“The hypothesis of this study was that treatment with CPAP would protect the patient only during the periods in which the treatment was in use,” the researchers wrote. “Such treatment would decrease the pathophysiological consequences associated with OSA, such as increases in sympathetic activity or mechanical stress in the vascular wall, which would increase plaque instability.”

The researchers concluded, “Adherence to treatment is complex to determine and there are other potential factors that could affect patient adherence, such as health education, motivation, attitude, self-efficacy, psychosocial factors, and other health care system–related features.”

Study limitations included not analyzing alternative treatments to OSA, insufficient statistical power to assess secondary outcomes, and a low proportion of women included in the studies.