Is obstructive sleep apnea an independent risk factor for stroke? A critically appraised topic

Background: Obstructive sleep apnea (OSA) is associated with hypertension, atrial fibrillation, coronary artery disease, congestive heart failure, and diabetes. These disorders are also risk factors for stroke. Objective: To determine whether OSA increases the risk of stroke independently of other cerebrovascular risk factors. Methods: The objective was addressed through the development of a structured critically appraised topic. This evidence-based methodology included a clinical scenario, structured question, search strategy, critical appraisal, results, evidence summary, commentary, and bottom line conclusions. Participants included consultant and resident neurologists, a medical librarian, clinical epidemiologists, and content experts in the field of sleep medicine and vascular neurology. Results: A large observational cohort study was selected and appraised to address this prognostic question. The unadjusted analysis revealed that OSA (apnea-hypopnea index >5) was associated with stroke or death from any cause (hazard ratio, 2.24; 95% confidence interval [CI], 1.30-3.86; P = 0.004). The adjusted OSA analysis retained a statistically significant association with stroke or death (hazard ratio, 1.97; 95% CI, 1.12-3.48; P = 0.01). In separate unadjusted analyses, OSA was associated with death and stroke with relative risks of 1.68 (95% CI, 1.10-2.25) and 5.16 (95% CI, 3.72-6.60), respectively. Conclusions: OSA independently contributes to stroke risk.