BackgroundObstructive sleep apnea (OSA) is common among patients with acute ischemic stroke and transient ischemic attack. We evaluated whether continuous positive airway pressure for OSA among patients with recent ischemic stroke or transient ischemic attack improved clinical outcomes.Methods and ResultsThis randomized controlled trial among patients with ischemic stroke/transient ischemic attack compared 2 strategies (standard or enhanced) for the diagnosis and treatment of OSA versus usual care over 1 year. Primary outcomes were National Institutes of Health Stroke Scale and modified Rankin Scale scores. Among 252 patients (84, control; 86, standard; 82, enhanced), OSA prevalence was as follows: control, 69%; standard, 74%; and enhanced, 80%. Continuous positive airway pressure use occurred on average 50% of nights and was similar among standard (3.9±2.1 mean hours/nights used) and enhanced (4.3±2.4 hours/nights used; P=0.46) patients. In intention‐to‐treat analyses, changes in National Institutes of Health Stroke Scale and modified Rankin Scale scores were similar across groups. In as‐treated analyses among patients with OSA, increasing continuous positive airway pressure use was associated with improved National Institutes of Health Stroke Scale score (no/poor, −0.6±2.9; some, −0.9±1.4; good, −0.3±1.0; P=0.0064) and improved modified Rankin Scale score (no/poor, −0.3±1.5; some, −0.4±1.0; good, −0.9±1.2; P=0.0237). In shift analyses among patients with OSA, 59% of intervention patients had best neurological symptom severity (National Institutes of Health Stroke Scale score, 0–1) versus 38% of controls (P=0.038); absolute risk reduction was 21% (number needed to treat, 4.8).ConclusionsAlthough changes in neurological functioning and functional status were similar across the groups in the intention‐to‐treat analyses, continuous positive airway pressure use was associated with improved neurological functioning among patients with acute ischemic stroke/transient ischemic attack with OSA.Clinical Trial RegistrationURL: http://www.clinicaltrials.gov. Unique identifier: NCT01446913.