A cardiovascular end-point benefit was observed with CPAP treatment among 364 patients receiving CPAP compared with 85 untreated The adjusted HR was 0.34 (95% CI, 0.20 0.58) for CPAP treatment. Although no randomized, controlled trials have been pub- lished on primary prevention, several randomized, controlled trials and cohort studies have evaluated the effectiveness of CPAP among patients with stroke and TIA (These data are reviewed in detail in the AHA secondary stroke prevention Among these secondary prevention studies, the one with the longest follow-up studied 189 patients after stroke with sleep apnea for 7 years, finding that patients who did not use CPAP had a much higher recurrent stroke rate than patients who used CPAP (32% versus 14%; P=0.021) and a higher adjusted incidence of nonfatal vascular events (HR, The number needed to treat to prevent 1 new vascular event was 4.9 patients (95% CI, 2 19). Adherence to CPAP can be measured directly by CPAP machines in hours per night used and proportion of nights used. The reported CPAP adherence has varied considerably across studies and across populations, with mixed data about differ- ences in adherence related to differences in CPAP mode (eg, autotitrating versus fixed pressure) or humidification use.742 746 Cognitive-behavioral interventions appear to improve CPAP Several studies have sought to identify predic- tors of CPAP adherence, and results have varied across stud- ies. 