Predicting Peritoneal Kt/Vurea Based on Single-Exchange Dialysate Effluent

Background:

Peritoneal dialysis (PD) adequacy is routinely evaluated using the urea clearance index (Kt/Vurea), a key indicator of small-solute clearance and treatment adequacy. The standard method for calculating peritoneal Kt/Vurea requires complete collection of 24-hour dialysate effluent, which is labor-intensive, time-consuming, and prone to errors arising from incomplete collection, inadequate mixing, and inaccurate sampling. Although proportional sampling from each exchange has been shown to yield results comparable to those obtained from complete 24-hour effluent collection, this approach still requires collection of all exchanges throughout the day. Previous studies have suggested that Kt/Vurea estimated from a single dialysate exchange may correlate with the standard measurement; however, these investigations were limited by small sample sizes and did not establish predictive equations. Therefore, a practical and accurate alternative for assessing peritoneal Kt/Vurea is still lacking.

Objective:

To develop and validate a prediction model for peritoneal Kt/Vurea based on single-exchange dialysate effluent in patients undergoing PD.

Methods:

This multicenter cross-sectional study will be conducted between 2026 and 2027 across four PD centers in China. Consecutive prevalent patients receiving manual PD will be screened for eligibility. Patients aged ≥14 years who have been receiving PD for at least one month will be included. Exclusion criteria comprise peritonitis or other acute complications within the preceding month, spontaneous ascites, inability to complete full dialysate collection during the study day, and refusal to provide informed consent. Demographic characteristics, primary kidney disease, comorbidities, and PD prescription parameters will be collected. On a designated study day, effluent from each dialysis exchange, 24-hour urine samples, and fasting blood samples will be obtained. The correlations between peritoneal Kt/Vurea calculated from individual exchanges and the reference peritoneal Kt/Vurea derived from complete 24-hour dialysate collection will be evaluated. Multivariable prediction models incorporating single-exchange effluent measurements and relevant clinical parameters will subsequently be developed and validated. Model performance will be assessed using measures of discrimination, calibration, and agreement with reference Kt/Vurea values.

Conclusions:

This study aims to establish and validate a simplified method for estimating peritoneal Kt/Vurea using single-exchange dialysate effluent. If validated, the proposed model may substantially reduce the burden associated with 24-hour dialysate collection while maintaining adequate accuracy for routine assessment of PD adequacy.