Diagnostic accuracy of the Berlin questionnaire in detecting obstructive sleep apnea in patients with resistant hypertension.

OBJECTIVES: Obstructive sleep apnea (OSA) is strongly associated with resistant hypertension. The Berlin questionnaire is the most widely used screening tool to identify patients at high risk of having OSA. The objective was to test the diagnostic accuracy of the Berlin questionnaire in detecting OSA in resistant hypertensive patients. METHODS: A cross-sectional analysis of 422 resistant hypertensive patients [31% men; mean (SD) age 62.4 (9.9) years] submitted to polysomnography (PSG), in whom the Berlin questionnaire was previously applied. OSA was defined by an apnea-hypopnea index of at least 5 per hour and moderate-to-severe OSA by an apnea-hypopnea index of at least 15. Statistical analysis included bivariate comparisons between patients at high and low risk by the Berlin questionnaire, and logistic regression to assess the predictors of agreement between the Berlin questionnaire and PSG. Sensitivity, specificity, positive and negative predictive values and likelihood ratios for the Berlin questionnaire in detecting OSA were calculated. RESULTS: OSA was diagnosed in 347 patients (82.2%) and moderate-to-severe OSA in 234 patients (55.5%). In patients at high risk, moderate-to-severe OSA was confirmed in 58.3%, whereas in those at low risk, it was excluded in 50.4%. The accuracy of the Berlin questionnaire in detecting OSA was 55.6%. The specificity, sensitivity, positive and negative predictive value of the Berlin questionnaire in detecting moderate-to-severe OSA was 40, 69, 58 and 50%, respectively. The positive and negative likelihood ratios were 1.15 and 0.78, with a very low agreement (kappa = 0.081). CONCLUSION: In a large cohort of resistant hypertensive patients, the Berlin questionnaire had a low accuracy of identifying patients with OSA and should not be used as a screening method for selecting patients to PSG.

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.

A reduced heart rate variability is independently associated with a blunted nocturnal blood pressure fall in patients with resistant hypertension.

BACKGROUND: A blunted nocturnal blood pressure (BP) fall is a marker of worse cardiovascular outcomes, and autonomic imbalance may be involved. The objective was to evaluate the associations between the nocturnal BP fall and heart rate variability (HRV) parameters in resistant hypertension. DESIGN AND METHODS: In a cross-sectional analysis, 424 resistant hypertensive patients performed 24-h ambulatory BP and Holter monitoring, and 221 patients also performed polysomnography. Time-domain HRV parameters evaluated were the standard deviation of all normal RR intervals (SDNN), the standard deviation of the averaged normal RR intervals for all 5-min segments (SDANN), the root mean square of differences between adjacent R-R intervals (rMSSD) and the percentage of adjacent R-R intervals that varied by more than 50 ms (pNN50). Multivariate linear and logistic regressions assessed associations between the nocturnal BP fall and HRV parameters. RESULTS: Two hundred and sixty-six patients (63%) presented a nondipping pattern. These patients had lower SDNN and SDANN than normal dipping patients, but equal rMSSD and pNN50. On multivariate analysis, after adjustments for several confounders, a reduced SDNN (<70 ms) implied a 2.9 to 3.4-fold [95% confidence interval (CI) 1.2-8.5] and a reduced SDANN (<50 ms) a 3.7 to 4.2-fold (95% CI 1.5-11.4) higher odds of having a nondipping pattern. Further adjustment for the presence and severity of obstructive sleep apnoea did not change the results. CONCLUSION: Reduced SDNN and SDANN, two HRV parameters that mainly reflect sympathetic overactivity, were independently associated with a blunted nocturnal BP fall in resistant hypertension. These relationships offer insight into physiopathological mechanisms linking the circadian BP variability to cardiovascular outcomes.