Factors associated with undiagnosed obstructive sleep apnoea among hypertensive patients: A multisite cross-sectional survey study in Taiwan

Aims and objectives: To investigate the distribution and risk factors associated with undiagnosed obstructive sleep apnoea among hypertensive patients. Background: Obstructive sleep Apnoea has been deemed a cardinal risk factor affecting cardiovascular event, and the condition is still frequently overlooked clinically. The lack of advanced diagnosis often causes hypertensive patients with obstructive sleep apnoea to miss opportunities for preventing chronic diseases. Design: A cross-sectional design. Methods: A total of 215 hypertensive participants were recruited from the cardiovascular outpatients of medical centre in northern and middle Taiwan. The Chinese version of Pittsburgh Sleep Quality Index, the Chinese version of the Epworth Sleep Scale and a portable sleep monitoring device were used for data collection. Logistic regression analysis was conducted to identify the factors affecting hypertensive patients with obstructive sleep apnoea, and a multinomial logistic regression analysis was used to examine the major influence factors for each obstructive sleep apnoea severity level. Results: 81.9% of the hypertensive participants were found having obstructive sleep apnoea. Concerning to the obstructive sleep apnoea severity, 50.0% of participants had mild obstructive sleep apnoea. After controlling the confounding variables, the supine position (odds ratio, 1.04; 95% CI, 1.01–1.07), SO₂ (odds ratio, 0.58; 95% CI, 0.38–0.89) and oxygen desaturation index (odds ratio, 2.70; 95% CI, 1.18–6.18) were significantly associated with obstructive sleep apnoea. Furthermore, severe obstructive sleep apnoea was significantly correlated with gender (odds ratio, 0.04; 95% CI, 0.00–0.66), excessive daytime sleepiness (odds ratio, 20.27; 95% CI, 1.58–26.97) and oxygen desaturation index (odds ratio, 4.05; 95% CI, 1.86–8.81). Conclusions: Nearly 82% of the hypertensive participants were found having undiagnosed obstructive sleep apnoea, and 80% of them were mild or moderate severity. Oxygen desaturation index, SO₂ and the supine position were found to be major predictors for obstructive sleep apnoea. Remarkably, oxygen desaturation index was the most significant predictor for mild, moderate and severe obstructive sleep apnoea. Relevance to clinical practice: Healthcare providers should enhance their sensitivities to hypertensive patients at a high risk for obstructive sleep apnoea by actively assessing common obstructive sleep apnoea symptoms and providing strategies to alleviate obstructive sleep apnoea symptoms.