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

Background and Objectives: 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. Materials and Methods: 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. Results: Significant differences were found among modalities for SBP (p = 0.009), DBP (p = 0.004), and MAP (p < 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 (p < 0.05). Differences versus pre- and mixed-HDF did not reach significance. Conclusions: 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).