MO088: Peridialytic and Intradialytic Blood Pressure Measurements are Not Valid Estimates of 44-Hour Ambulatory Blood Pressure in Patients With Intradialytic Hypertension

Abstract

Abstract BACKGROUND AND AIMS In contrast with pre- and post-dialysis 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 interdialytic BP in a distinct hemodialysis population, patients with intradialytic-hypertension (IDH). METHOD 45 patients with IDH (defined as: SBP rise ≥ 10 mmHg from pre- to post-dialysis and post-dialysis SBP ≥ 150 mmHg) with valid 48-h ABPM and 197 without IDH were included in this analysis. With 44-h BP used as reference method, we tested the accuracy of the following BP metrics: Pre- and post-dialysis, intradialytic, intradialytic plus pre/post-dialysis readings and scheduled interdialytic BP (out-of-dialysis day: readings at 8:00 am, 8:00 pm or their average). RESULTS In patients with IDH, peri-dialytic 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 κ-statistic for diagnosing 44-h SBP ≥ 130 mmHg were low for pre-dialysis (72.5%/40.0%, κ-statistic = 0.074) and post-dialysis (90.0%/0.0%, κ-statistic = −0.110), intradialytic (85.0%/40.0%, κ-statistic = 0.198) and intradialytic plus pre/post-dialysis SBP (85.0%/20.0%, κ-statistic = 0.043). Averaged-interdialytic-SBP showed high values of sensitivity/specificity (97.5%/80.0%) and strong agreement (κ-statistic = 0.775). In ROC-analyses, the peri- and intradialytic BP metrics showed bad performance with low Area-Under-the-Curve values; scheduled interdialytic SBP/DBP had the largest AUC (0.967/0.951), along with the highest sensitivity(90.0%/88.0%) and specificity(100.0%/90.0%) for detecting elevated 44-h BP. CONCLUSION In patients with IDH, averaged-scheduled-interdialytic but not pre- and post-dialysis, nor intradialytic BP recordings show reasonable agreement with ambulatory BP. Interdialytic BP recordings only could be used for hypertension diagnosis and management in these subjects.