Nocturia is an independent predictor of severe obstructive sleep apnea in patients with ischemic stroke

Severe obstructive sleep apnea (OSA) increases the risk of stroke recurrence and mortality after stroke. Since nocturia is common in post-stroke patients with OSA, this study explored the predictive role of nocturia for severe OSA in patients with ischemic stroke. This was a cross-sectional, prospective study involving 65 consecutive patients with ischemic stroke admitted to rehabilitation ward. All participants received polysomnography and clinical assessments, including a 3-day urinary frequency - volume recording. Differences in study variables between patients with and without severe OSA were compared, and logistic regression analyses with backward selection procedures were used to assess the relationship between OSA severity and nocturia. Patients with severe OSA were older (69.6 ± 9.9 vs. 62.6 ± 11.5 year), had a significantly higher desaturation index (37.9 ± 16.1 vs. 8.8 ± 6.1 episodes/night) and had a higher frequency of nocturia (2.2 ± 1.0 vs. 1.5 ± 0.8 episodes/night) than those without. In addition, men with severe OSA had a larger neck circumference (409 ± 26 vs. 381 ± 32 mm) than those without. The frequency of nocturia, age, sex, and interaction between sex and neck circumference remained significant in the final regression model for severe OSA. In this model, the area under the receiver operating characteristic curve was 0.87 (95% CI 0.79-0.96; P<0.001) with sensitivity and specificity of 80.6 and 82.8%, respectively. The odds ratio of nocturia was highest (3.5) among the four variables. Nocturia is an independent predictor for severe OSA, and the final prediction model might be used when screening for severe OSA in patients with ischemic stroke.