Supplementary Material for: Association of Peridialysis Blood Pressure and Its Variability with Cardiovascular Events in Hemodialysis Patients

Background/Aims: Blood pressure variability (BPV) is a novel cardiovascular risk factor for the population undergoing hemodialysis (HD). Methods: We conducted a retrospective cohort study of 526 HD patients. Four short-term peridialysis BPV metrics were analyzed: systolic blood pressure (SBP) change, SBP coefficient of variation (CV), SBP intradialytic average real variability (ARV), and absolute SBP residual. Multi variate analysis with Cox regression models were used to account for the potential confounders. Results: Short-term BPV is found to be affected by age, pre-dialysis SBP, antihypertensive drugs, dialysis time, and vascular access. Calcium-channel blockers (CCBs) were found to be associated with lower BPV than those on non-CCB therapy or no antihypertensive drugs. Patients dialyzed in the morning had a greater absolute SBP change than those dialyzed in the afternoon or evening. Patients using fistulas had a lower BPV than catheters. Higher BPV metrics including SBP CV (unadjusted hazard ratio [HR]: 1.37, 95% confidence interval [CI] 1.14-1.66, p=0.001), SBP intradialytic ARV (unadjusted HR: 1.46, 95% CI: 1.20-1.77, p< 0.001), and SBP residual (unadjusted HR: 1.47, 95% CI: 1.21-1.79, p< 0.001) were associated with a greater risk of cardiovascular events. After complete multivariate adjustment for other potential confounders, the HR remained statistically significant for SBP intradialytic ARV (HR 1.31, 95% CI: 1.04-1.66, p=0.024). Conclusion: Peridialytic BPV may be a potential target for improved blood pressure (BP) management in HD patients. Each short-term BPV metric has different advantages and disadvantages and should be applied according to the clinical context and purpose.