Association Between Residual Urine Volume and QT Dispersion in Peritoneal Dialysis Patients

Background: Residual kidney function is clinically important in patients undergoing peritoneal dialysis (PD). QT dispersion (QTd) is a measurement-sensitive electrocardiographic surrogate of ventricular repolarization heterogeneity. This study evaluated the association between residual urine volume and QTd in patients receiving PD. Methods: This cross-sectional study included 88 adults receiving PD, categorized according to residual urine volume as <250 mL/day (n=13) or ≥250 mL/day (n=75). The primary analyses comprised the between-group comparison of QTd, the continuous residual-urine-volume–QTd association, and adjusted linear regression. QTd was compared using the Mann–Whitney U test, and the continuous association was assessed using Spearman rank correlation. Log10-transformed QTd was modeled using multivariable linear regression with heteroscedasticity-consistent type 3 robust standard errors. Secondary comparisons were considered exploratory and evaluated using the Benjamini–Hochberg false-discovery-rate procedure. Results: The mean age was 57±13 years, and 34 participants (38.6%) were female. QTd was greater in the <250-mL/day group than in the ≥250-mL/day group [50 (50–60) vs. 43 (40–52) ms; P=0.040]. Among 85 participants with both measurements available, residual urine volume was inversely correlated with QTd (Spearman ρ=−.282; 95% CI, −.453 to −.096; P=0.009). In the adjusted model, lower residual urine volume was associated with higher log10-QTd (standardized β=−.287; P=.008). Lower serum albumin was also associated with higher log10-QTd (standardized β=−.341; P=0.004), whereas age and serum phosphorus were not associated with the outcome. Conclusion: Lower residual urine volume was associated with greater QTd in this cross-sectional PD cohort, including after multivariable adjustment. These findings represent statistical associations and do not establish causality, arrhythmic risk, or prognostic significance. Confirmation in larger prospective studies using standardized electrocardiographic assessment and clinical cardiovascular outcomes is needed.