A meta-analysis of 5 prospective studies that included 8435 participants identified an OR for incident stroke risk of 2.24 (95% CI, 1.57 3.19).734 This meta-analysis also found that increased stroke risk is associated with increasing sleep apnea severity with an OR of 1.35 (95% CI, 1.25 1.45) for every 10-unit increase in AHI. A study of 50 men with sleep apnea and 15 obese male control subjects found that silent brain infarctions on MRI were more common among patients with moderate to severe sleep apnea than among control subjects or patients with mild sleep apnea Although alternative therapeutic strategies exist, the main- stay of sleep apnea treatment is continuous positive airway pressure (CPAP), which improves a variety of clinical out- comes (eg, daytime sleepiness).730,736 No randomized trial has evaluated the effectiveness of CPAP on primary stroke preven- tion. The existing longitudinal cohort data indicate that CPAP treatment is associated with a reduction in cardiovascular risk among patients with sleep apnea compared with patients who are not treated with CPAP even after adjustment for vascular risk factors and that this finding is most robust for patients with the most severe sleep apnea.737 739 For example, a study of 264 healthy subjects, 403 untreated patients with sleep apnea, and 372 patients with CPAP treatment for 10 years739 had a combined vascular event end point that included fatal or non- fatal stroke or MI or acute coronary syndrome requiring car- diac intervention. 