Association between refractory hypertension and obstructive sleep apnea

Background: Obstructive sleep apnea (OSA) increases the risk for mild hypertension, but its relationship to refractory hypertension (RHT) has not been systematically examined. We previously reported a high prevalence of OSA in patients with RHT, but did not have a control group with which to compare. Rapid eye movement (REM) sleep deprivation can raise blood pressure in animals. However, a potential relationship of OSA and REM sleep time with RHT has not been examined. Objective: To determine whether, compared with patients with well controlled hypertension, those with RHT have a higher prevalence of OSA (apnea-hypopnea index ≥ 10 per hour of sleep) and shorter REM sleep time. Methods: We compared the prevalence of OSA and sleep structure in 42 patients with RHT with 22 patients with controlled hypertension, matched for age, sex and BMI. Results: Compared with the controlled hypertension group, the RHT group had a significantly higher prevalence of OSA (81 versus 55%, P = 0.03) and less REM sleep time (47.0 ± 4.5 versus 63.2 ± 4.9 min, P = 0.02). Multivariate analysis revealed significantly increased odds of having RHT associated with OSA independent of other risk factors (adjusted odds ratio, 3.994; 95% confidence interval, 1.191-13.388). Reduced REM sleep time was also independently associated with the presence of RHT (adjusted odds ratio, 1.025; 95% confidence interval, 1.002-1.049). Conclusion: OSA and reduced REM sleep time are associated with increased odds of having RHT and, therefore, may play roles in its pathogenesis.