Multiple studies have shown a small reduction in BP readings (generally about 2 mm Hg) with PAP treatment in nonresistant hypertensive patients with OSA who are sleepy.26 Conversely, the literature is mixed on whether treatment of non-sleepy patients with OSA reduces BP. One long-term study demonstrated a small (1.89 mm Hg systolic, 2.19 mm Hg diastolic) BP reduction effect of PAP in non-sleepy subjects with OSA.27 Similarly, research has shown mandibular advancement devices to lower BP in patients with OSA, in a range similar to that achieved with PAP.28 Whether very small reductions in BP improve important clinical outcomes such as stroke or heart disease is unknown.
CV risk: Again, findings are mixed
The SAVE study is the largest randomized investigation of the effect of treatment of OSA with PAP for secondary prevention of cardiovascular events.29 The trial involved 2717 adults with cardiovascular disease, moderate-to-severe OSA, and minimal sleepiness, and had as its primary composite endpoint death from cardiovascular causes, myocardial infarction (MI), stroke, hospitalization for unstable angina, heart failure, or transient ischemic attack. Patients with severe daytime sleepiness or severe hypoxemia were excluded. The study found no difference between PAP and usual care in the primary outcome, despite a significant reduction in the AHI from a mean of 29 at baseline to 3.7 with PAP treatment.
Similarly, a randomized controlled trial (RCT) of 725 patients with non-sleepy OSA failed to show a reduction in cardiovascular events or in the development of hypertension.30 Peker et al31 randomized 244 adults with recently revascularized coronary artery disease and OSA without daytime sleepiness to auto-titrating CPAP or usual care and did not find a statistically significant difference in revascularization, MI, stroke, or cardiovascular mortality; however, those patients who were compliant with CPAP for ≥ 4 hours/night did have a statistically significant reduction in the combined endpoint.
In contrast, a trial of patients with first-ever stroke and moderate-to-severe OSA who were randomized to early nasal CPAP or usual care demonstrated better 5-year cardiovascular survival for the patients in the CPAP group, and a trend toward better cardiovascular event-free survival.32 Degree of daytime sleepiness was not stated in this study.
A recent meta-analysis of RCTs failed to find a reduction in major adverse cardiovascular events (MACE) in patients with moderate-to-severe OSA treated with PAP.33 In this study, subgroup analysis documented benefit in patients who were adherent with PAP for ≥ 4 hours/night. A larger meta-analysis, however, did not find a reduction in MACE even in the adherent subgroup.34
