Prevalence and Associated Factors of Obstructive Sleep Apnea in Patients with Resistant Hypertension

BACKGROUND Obstructive sleep apnea (OSA) syndromes are strongly associated with resistant hypertension, although this has not been systematically examined. The aim of our study was to investigate the prevalence of OSA and its associated factors in a large cohort of resistant hypertensive patients. METHODS A cross-sectional analysis with 422 resistant hypertensive patients (31.3% men; mean age = 62.4 +/- 9.9 years) submitted to a full-night polysomnography. The presence of OSA was defined by an apnea-hypopnea index (AHI) > 5 per hour and moderate/severe OSA was defined by an AHI > 15. Statistical analysis included bivariable comparisons between patients with and without moderate/severe OSA and logistic regressions to assess the independent correlates of OSA severity. RESULTS Three-hundred forty-seven patients (82.2%) had OSA, and 234 patients (55.5%) had moderate/severe OSA. Patients with moderate/severe OSA were more frequently elderly and obese men with larger waist and neck circumferences, had higher prevalences of diabetes and left ventricular hypertrophy, and had higher proteinuria than patients with no/mild OSA. No difference was found in plasma aldosterone and renin activity. Nighttime systolic blood pressures and pulse pressures were higher in moderate/severe OSA, with lower nocturnal blood pressure fall. In multivariable logistic regression, male sex, older age, diabetes, obesity, increased waist and neck circumferences, and nighttime systolic blood pressure were the independent correlates of moderate/severe OSA. CONCLUSIONS Resistant hypertensive patients had a very high prevalence of OSA, and patients with moderate/severe OSA had an adverse ambulatory BP profile, with higher nighttime systolic blood pressures and pulse pressures and higher prevalence of nondipping patterns. Other correlates of OSA severity were mainly demographic-anthropometric variables.