ACCURACY OF PERIDIALYTIC, INTRADIALYTIC AND SCHEDULED INTERDIALYTIC RECORDINGS FOR DIAGNOSING HIGH AMBULATORY BLOOD PRESSURE IN HEMODIALYSIS

Abstract Background and Aims Hypertension is highly prevalent in hemodialysis patients. Current recommendations suggest the use of ambulatory-BP-monitoring (ABPM) as the gold-standard for hypertension diagnosis and management in these subjects. This study assessed the accuracy of peridialytic, intradialytic and scheduled interdialytic recordings in diagnosing high 44-h interdialytic BP. Method A total of 242 hemodialysis patients that underwent valid 48-h ABPM were included in the analysis. We used ambulatory BP as reference standard and 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 44-h SBP/DBP levels had significant differences with and pre- or post-dialysis BP, but no or minor differences with any of the other BP metrics. 44-h SBP and DBP correlated strongly with Intradialytic (r=0.713/0.753, p<0.001), Intradialytic plus pre/post-dialysis (r=0.725/0.758, p<0.001) and averaged Scheduled interdialytic BP (r=0.874/0.823, p<0.001). Bland-Altman plots showed absence of systemic bias for all index metrics, but large between-method difference and wider 95% limits of agreement for pre- and post-dialysis BP compared to Intradialytic, Intradialytic plus pre/post-dialysis and averaged Scheduled interdialytic BP. In ROC-analysis for diagnosing 44-h SBP≥130mmHg, the Area-Under-the-Curve of pre-dialysis (0.723) and post-dialysis SBP (0.746) were significantly lower than that of Intradialytic (0.850), Intradialytic plus pre/post-dialysis (0.850) and Scheduled interdialytic SBP (0.917) (z-test, p<0.001 for all pairwise comparisons). The corresponding sensitivity/specificity values were 76.6%/54.5%, 78.7%/59.4%, 73.0%/81.2%, 68.1%/88.1% and 82.3%/89.1%, respectively. Similar observations were made for DBP. Conclusion In contrast to pre- and post-dialysis BP, the average of intradialytic, intradialytic plus pre/post-dialysis or scheduled interdialytic BP recordings show reasonable agreement with ambulatory BP and may be used for hypertension diagnosis and management in hemodialysis.