Accuracy of 24 h ambulatory blood pressure recordings for diagnosing high 44 h blood pressure in hemodialysis: a diagnostic test study

Hypertension is highly prevalent in hemodialysis patients. Ambulatory-BP-monitoring(ABPM) during the 44 h interdialytic interval is recommended for hypertension diagnosis and management in these subjects. This study assessed the diagnostic accuracy of fixed 24 h ABPM recordings with 44 h BP in hemodialysis patients. 242 Greek hemodialysis patients that underwent valid 48 h ABPM(Mobil-O-Graph NG device) were included in the analysis. We used 44 h BP as reference method and tested the accuracy of the following BP metrics: 1st 24 h without HD period (20 h-1st), 1st 24 h including HD period (24 h–1st) and 2nd 24 h(24 h–2nd). All studied metrics showed strong correlations with 44 h SBP/DBP (20 h–1st: r = 0.973/0.978, 24 h–1st: r = 0.964/0.972 and 24 h–2nd: r = 0.978/0.977, respectively). In Bland-Altman analysis, small between-method differences (−1.70, −1.19 and +1.45 mmHg) with good 95% limits-of agreement([−10.83 to 7.43], [−11.12 to 8.74] and [−6.33 to 9.23] mmHg, respectively) for 20 h–1st, 24 h–1st and 24 h–2nd SBP were observed. The sensitivity/specificity and κ-statistic for diagnosing 44 h SBP ≥ 130 mmHg were high for 20 h–1st SBP(87.2%/96.0%, κ-statistic = 0.817), 24 h–1st SBP(88.7%/96.0%, κ-statistic = 0.833) and 24 h–2nd SBP (95.0%/88.1%, κ-statistic = 0.837). Similar observations were made for DBP. In ROC-analyses, all studied BP metrics showed excellent performance with high Area-Under-the- Curve values (20 h–1st: 0.983/0.992; 24 h–1st: 0.984/0.987 and 24 h–2nd: 0.982/0.989 for SBP/DBP respectively). Fixed 24 h ABPM recordings during either the first or the second day of interdialytic interval have high accuracy and strong agreement with 44 h BP in hemodialysis patients. Thus, ABPM recordings of either the first or the second interdialytic day could be used for hypertension diagnosis and management in these subjects.