Defining the Optimal Frequency of Dialysis Adequacy Test for Patients on Peritoneal Dialysis

Background: Peritoneal Dialysis (PD) is a cost-effective treatment for end-stage kidney disease, with the adequacy of small solute clearance being a key factor in determining the PD regimen. Although regular monitoring of small solute clearance is recommended, recent guidelines emphasize a person-centered approach. We hypothesize that peritoneal Kt/V(urea) remains stable in most patients and does not require frequent monitoring. Methods: We reviewed 11427 PD adequacy tests in 1874 PD patients. The serial change in Kt/V-PD was compared. The effect of daily exchange volume, peritonitis episodes, PD solution osmolality, duration of dialysis, and other baseline parameters were explored. Results: The median duration between two dialysis adequacy tests was 7.0 months (IQR 5.6 to 11.0 months). The average change in Kt/V-PD between two tests was 0.024 ± 0.319. The change in Kt/V-PD was significantly higher after an increase in exchange volume than those with a static PD exchange volume (0.176 ± 0.453 vs 0.012 ± 0.302, p<0.0001). When dialysis adequacy test pairs that had a static PD exchange volume were analyzed, the change in Kt/V-PD did not differ between tests that were interposed with peritonitis episodes and those without (0.006 ± 0.317 vs 0.013 ± 0.300, p = 0.4). The change in Kt/V-PD was similar when the adequacy test was repeated after an increase in PD solution osmolality as compared to those with a static PD regimen (-0.011 ± 0.367 vs 0.014 ± 0.296, p = 0.1). There was no correlation between the change in Kt/V-PD and the duration between two adequacy tests (r = 0.002, p = 0.8). Conclusion: Our result shows that Kt/V-PD remains stable in most patients within 12 months and does not require frequent monitoring.