Obstructive sleep apnea (OSA) has serious cardiovascular consequences and increases the risk of stroke.1,2 OSA is common in patients with stroke3,4 and is associated with impaired quality of life, reduced cognitive function, and excessive fatigue,5–7 conditions that are common in stroke victims and that may delay poststroke recovery.8–10 It is possible that treating OSA could improve clinical recovery in patients with stroke. Continuous positive airway pressure (CPAP) is the “gold standard” treatment for OSA; however, there have been few studies of CPAP use in patients poststroke, and the ability for CPAP to definitively improve outcomes has yet to be established in this population. Part of the motivation for this review stems from our experience with a clinical trial that closed due to futility.1 As a “postmortem” on the trial’s closure, we scrutinized the literature, summarizing outcome data in the area and considering recruitment experience in similar trials. Finally, we comment on possible study design characteristics that might make future trials more successful. ### Number of Studies A PubMed search up to November 2011 using the terms stroke OR transient ischemic attack AND apnea AND continuous positive airway pressure revealed 17 published studies (online-only Data Supplement Table I). Studies were heterogeneous with regard to timing of treatment onset, follow-up assessment timing, and outcomes studied, making a meta-analysis inappropriate; therefore, we conducted a systematic qualitative review of the literature. Nine studies were observational,11–19 3 of which examined the same cohort of patients over time.16–18 Six studies randomized patients to CPAP versus treatment as usual (TAU),20–26 and one study randomized patients to CPAP or sham CPAP.27 On average, studies followed a small number of patients: observational studies included a median of 22 patients who …