The Association between Long- and Intra-Dialytic Blood Pressure Variability with All-Cause Mortality in Hemodialysis Patients

Abstract

BACKGROUND: Blood pressure variability (BPV) is a potential prognostic predictor for all-cause mortality. OBJECTIVES: We conducted a retrospective cohort study to compare the prognostic value of long-term BPV with intra-dialytic BPV in hemodialysis (HD) patients. MATERIALS AND METHODS: We included 611 HD patients and collected their baseline blood pressure (BP) measurements for 1 year and monitored them for 40 months. Long-term BPV was assessed by pre-dialysis BP SD and pre-dialysis absolute BP residual metric. Intra-dialytic BPV was assessed by intra-dialytic BP average real variability and intra-dialytic absolute BP residual. RESULTS: Long-term systolic BPV showed a weak correlation with mean BP, but a stronger correlation with intra-dialytic BPV. High long-term systolic blood pressure (SBP) SD and long-term SBP residual metrics were associated with high all-cause mortality (p = 0.0084 and 0.0056, respectively), while no such association was found for intra-dialytic BPV or diastolic BPV. According to receiver operating characteristic curve with mortality as dependent variable, long-term SBP residual metric showed the strongest prognostic ability (area under curve [AUC] 0.679, p = 0.0006), which was even stronger in patients with BP ≥140/90 mm Hg (AUC 0.713, p = 0.0004). After completely adjusting for confounders, long-term SBP residual metric remained significantly associated with all-cause mortality (hazard ratio 1.628 per quartile; 95% CI 1.086-2.441). CONCLUSIONS: Our results suggest long-term SBP residual metric to be a better predictor of all-cause mortality in HD patients, which could be used as an additional target for BP management.