Severity of Obstructive Sleep Apnea in Patients With and Without Cardiovascular-Related Diseases

BACKGROUND: Previous studies have often investigated the association of obstructive sleep apnea (OSA) with cardiovascular morbidity and mortality, but the possibility of reverse causation has not been clearly defined. OBJECTIVE: To examine if the presence of any of the cardiovascular-related diseases, including hypertension, diabetes mellitus, coronary artery disease, and/or cerebrovascular disease, correlates with more severe OSA. METHODS: This was a retrospective study where all patients age ≥ 18 years referred to our sleep laboratory for suspected OSA were included. The data from the full-night baseline and split-night polysomnographic reports were reviewed. Data were then evaluated by logistic regression analysis to compare between 2 groups, the severity of OSA (respiratory disturbance index [RDI] < 15 vs RDI ≥ 15, and RDI < 5 vs RDI ≥ 5), other polysomnographic variables and daytime sleepiness score (Epworth Sleepiness Scale [ESS] score < 10 and ≥ 10). RESULTS: 190 patients were analyzed. The patients with any of the cardiovascular-related diseases were noted to have more severe sleep apnea (RDI ≥ 15), with an adjusted odds ratio of 3.24. Sleep efficiency ≥ 90% and mean oxygen saturation ≥ 95% were observed less commonly in the patients with any of the cardiovascular-related diseases (adjusted odds ratios of 0.45 and 0.36, respectively). There was no statistically significant difference in ESS score. CONCLUSIONS: Patients with any of the cardiovascular-related diseases are at a higher risk of having moderate to severe OSA without significant increase in daytime sleepiness. Therefore, we suggest that patients with any of the cardiovascular-related diseases should be screened for OSA, even if they are asymptomatic.