Standardized Peridialytic Blood Pressures for Diagnosing Arterial Hypertension in Patients on Chronic Hemodialysis
Abstract
Background. The relevance of peridialytic blood pressures for diagnosing hypertension is controversial. Standardized peridialytic BPs have not yet been evaluated for the positive diagnosis and evaluation of hypertension severity in chronic hemodialysis patients.
Aim. To evaluate the utility of standardized peridialytic BP for diagnosing hypertension, defined according to the results of 24-hour ambulatory blood pressure monitoring(ABPM).
Methods. Thirty-five chronic hemodialysis patients with a dialysis vintage of more than 3 months were included. 10% (n=4) of the patients initially selected (n=39) refused ABPM. Predialysis BP was measured according to the NKF-K/DOQI guidelines. Intradialytic and postialytic BPs were measured using the ABPM device, which was attached to the patients during the first hour of dialysis and was detached 24 hours after the end of the dialysis session. Peridialytic BPs (predialysis systolic and dyastolic BP, average of intradialytic BP and postdialysis BP) were used to predict hypertension or insufficient BP control, defined as 24 hours average systolic BP(24 h SBP) >140 mm Hg or 24 hours average dyastolic BP(24 h DBP) >90 mm Hg. Bland Altman plots were used to evaluate the mean difference (bias) and the concordance limits (±2SD) and the concordance coefficient was determined. Sensitivity and specificity of peridialytic BP were calculated using receiver-operating characteristic (ROC) curves, including area under the curve (AUC) (software Medcalc 12.2.1). Univariate logistic regression was performed with presence of hypertension (HTN) as the dependent variable and peridialytic BPs as independent variables.
Results and discussion. The studied group did not signifficantly differ from the group of patients prevalent in the center (n=126). Prevalence of systolic HTN (defined as 24 hour systolic BP >140 mm Hg) was 51%. 74% of patients in the study group were treated with antihypertensives. BP control was unsatisfactory in 53,8% for SBP and 23.1% for DBP. Four patients (44%) of the untreated group had systolic HTN. Predialytic DBP, intradialytic and postdialytic BPs had sensitivities and specificities over 89% for diagnosing HTN. All peridialytic BPs had AUC under the ROC curves of >0,8. Predialysis SBP was the most biased (14 mm Hg) and overestimated interdialysis BP. The other peridialytic BPs had smaller bias, but had wide limits of agreement on the Bland-Altman plots.
Conclusions.Undiagnosed and uncontrolled HTN showed a high prevalence (44% and 54%). Peridialytic BPs can be used for the positive diagnosis of HTN (area under the ROC curve >0,8). We found substantial concordance between postdialysis BPs and 24h BPs.