Impact of High-Efficiency Dialysis Modalities on Interdialytic Blood Pressure Profiles: A Randomized Cross-Over Study

<i>Background and Objectives:</i> Interdialytic blood pressure (BP) better reflects volume status and cardiovascular risk in hemodialysis (HD) patients than peridialytic readings. High-efficiency dialysis techniques-online hemodiafiltration (HDF) in pre-, post-, and mixed-dilution modes, and expanded hemodialysis (HDx) with medium cut-off membranes-aim to improve solute clearance and hemodynamic stability. Their comparative impact on interdialytic BP control remains unclear. This randomized cross-over study compared interdialytic BP profiles across these modalities under standardized treatment conditions. <i>Materials and Methods</i>: Sixteen clinically stable adults with end-stage kidney disease sequentially underwent high-flux HD, HDx, and HDF in pre-, post-, and mixed-dilution configurations, each for one month. Dialysis prescriptions, dry weight, and antihypertensive therapy remained constant. Home BP was measured twice daily on non-dialysis days, yielding ~3600 observations. Systolic (SBP), diastolic (DBP), and mean arterial pressure (MAP) were analyzed by repeated-measures ANOVA with Bonferroni correction. <i>Results</i>: Significant differences were found among modalities for SBP (<i>p</i> = 0.009), DBP (<i>p</i> = 0.004), and MAP (<i>p</i> < 0.001). HDx achieved the lowest mean BP values-SBP 129 (95% CI 127-131) mmHg; DBP 74 (95% CI 73-75) mmHg; MAP 93 (95% CI 91-94) mmHg-significantly lower than high-flux HD and post-dilution HDF (<i>p</i> < 0.05). Differences versus pre- and mixed-HDF did not reach significance. <i>Conclusions</i>: HDx provided modest but consistent reductions in interdialytic BP compared with diffusive and convective high-efficiency modalities. Trial Registration: Ethics Committee of the Medical University of Gdańsk (NKBBN/479-759/2022).