Association of Serum Phosphorus Levels With QT Prolongation in Patients With End‐Stage Kidney Disease: Insights From the Analysis of Peritoneal Dialysis Patients

Background Serum phosphorus (P) levels have been associated with QT interval prolongation in patients undergoing hemodialysis. However, it is unclear whether this association exists in patients undergoing peritoneal dialysis (PD) in the absence of acute electrolyte fluctuations. Methods This cross‐sectional study was conducted among adult patients on maintenance PD who were enrolled in the Japanese Society for Dialysis Therapy and Renal Data Registry in 2020. After assessing patient characteristics, a linear regression analysis was performed with serum calcium (Ca) and P levels as exposures and rate‐corrected QT (QTc) interval as the outcome. Results This study included 3566 patients with a mean QTc of 449.1 ± 34.5. Of these, 251 (7.0%) had QT interval prolongation (QTc > 500 msec). Univariate analysis showed a statistically significant association between lower corrected Ca and longer QTc interval, as well as higher P and longer QTc. Only the association between higher P and longer QTc remained statistically significant in multivariate analysis. Restricted cubic spline showed that QTc tended to increase with lower corrected Ca, whereas QTc time tended to increase with higher phosphate levels. Conclusion An association between hypocalcemia and QT interval prolongation was confirmed in patients undergoing PD, similar to findings in hemodialysis. However, unlike in hemodialysis, an association between serum P levels and QT interval was found only in cases of hyperphosphatemia and not in the context of hypophosphatemia and QT interval prolongation.