Peridialytic and intradialytic blood pressure metrics are not valid estimates of 44-h ambulatory blood pressure in patients with intradialytic hypertension

Purpose In contrast to peridialytic blood pressure (BP), intradialytic and home BP measurements are accurate metrics of ambulatory BP load in hemodialysis patients. This study assessed the agreement of peridialytic, intradialytic, and scheduled interdialytic recordings with 44-h BP in a distinct hemodialysis population, patients with intradialytic hypertension (IDH). Methods This study included 45 IDH patients with valid 48-h ABPM and 197 without IDH. With 44-h BP used as reference method, we tested the accuracy of the following BP metrics: Pre- and post-dialysis, mean and median intradialytic, mean intradialytic plus pre/post-dialysis, and scheduled interdialytic BP (out-of-dialysis day: mean of 8:00am/8:00 pm readings). Results In IDH patients, peridialytic and intradialytic BP metrics showed at best moderate correlations, while averaged interdialytic SBP/DBP exhibited strong correlation (r = 0.882/r = 0.855) with 44-h SBP/DBP. Bland-Altman plots showed large between-method-difference for peri- and intradialytic-BP, but only + 0.7 mmHg between-method difference and good 95% limits of agreement for averaged interdialytic SBP. The sensitivity/specificity and kappa-statistic for diagnosing 44-h SBP >= 130 mmHg were low for pre-dialysis (72.5/40.0%, kappa-statistic = 0.074) and post-dialysis (90.0/0.0%, kappa-statistic = - 0.110), mean intradialytic (85.0/40.0%, kappa-statistic = 0.198), median intradialytic (85.0/60.0%, kappa-statistic = 0.333), and intradialytic plus pre/post-dialysis SBP (85.0/20.0%, kappa-statistic = 0.043). Averaged interdialytic SBP showed high sensitivity/specificity (97.5/80.0%) and strong agreement (kappa-statistic = 0.775). In ROC analyses, scheduled interdialytic SBP/DBP had the highest AUC (0.967/0.951), sensitivity (90.0/88.0%), and specificity (100.0/90.0%). Conclusion In IDH patients, only averaged scheduled interdialytic but not pre- and post-dialysis, nor intradialytic BP recordings show reasonable agreement with ABPM. Interdialytic BP recordings only could be used for hypertension diagnosis and management in these subjects.