Clinical Question

Does the use of continuous positive airway pressure (CPAP) reduce the likelihood of cardiovascular events?

Bottom Line

Compared with usual care, the use of CPAP provides a modest improvement in daytime sleepiness, but does not reduce the likelihood of cardiovascular events, even in a high-risk population. (Level of Evidence = 1b)

Synopsis

Because patients with moderate to severe obstructive sleep apnea have frequent episodes of hypoxia, is it possible that those episodes can trigger cardiovascular events? This physiologically plausible hypothesis has been widely considered, and observational studies have provided it with some support, but it has never been tested in a clinical trial. These investigators, mostly from Australia and China, recruited patients 45 to 75 years of age with known coronary artery or cerebrovascular disease and moderate to severe obstructive sleep apnea. The latter was defined as at least 12 drops per hour in the oxygen saturation of at least 4%. Patients with severe daytime sleepiness, very severe hypoxemia, or Cheyne-Stokes respirations were excluded. Although patients knew whether they were using CPAP, outcomes were adjudicated by masked outcome assessors.

The mean age of the 2,687 participants was 61 years, most were men, and the mean body mass index was 29 kg per m². They were randomized to use CPAP or to continue usual care. At the end of follow-up (mean = 3.7 years), there was no difference between groups in the composite outcome of cardiovascular death, myocardial infarction, stroke, acute coronary syndrome, hospitalization for heart failure, or transient ischemic attack (17.0% for the CPAP group, 15.4% for the usual care group; P = .34). There was no significant difference in any of the individual outcomes. The CPAP group had greater reductions in sleepiness than the usual care group, approximately 2.5 points on the 24-point Epworth Sleepiness Scale, which is of marginal clinical significance.

Study design: Randomized controlled trial (single-blinded)

Funding source: Industry plus government

Allocation: Concealed

Setting: Outpatient (any)

Reference:McEvoyRDAnticNAHeeleyEet alSAVE Investigators and Coordinators. CPAP for prevention of cardiovascular events in obstructive sleep apnea. N Engl J Med2016;375(10):919–931.