Positive association of residual kidney function with hemoglobin level in patients on peritoneal dialysis independent of endogenous erythropoietin concentration

Background: How residual kidney function (RKF) functions in the prevention of anemia in peritoneal dialysis (PD) patients is unclear. In this study, we investigated the association between RKF and hemoglobin (Hb) level. Methods: We performed a cross-sectional analysis of the association between RKF, defined as the mean renal creatinine and urea clearance (rCUC), and the Hb level in 50 PD patients registered retrospectively. The independent variable was mean rCUC as continuous or categorical variable by tertile, and the dependent variable was Hb level as continuous or dichotomous variable using Hb cutoff of 10 g/dL. We conducted a multivariable regression analysis and calculated the c-statistic for Hb level < 10 g/dL using a receiver operating characteristic curve. Results: In multivariable regression analysis, mean rCUC was significantly associated with Hb level independent of dose of erythropoiesis-stimulating agent (ESA) and endogenous erythropoietin (eEPO) concentration. Multivariable adjusted least square means of the Hb level were higher with increase in the mean rCUC tertile. The c-statistic (95% confidential interval) for a Hb level < 10 g/dL was significantly greater in the model with mean rCUC than without [0.931 (0.789–0.980) vs. 0.856 (0.697–0.939), P = 0.044]. Conclusion: A decline in RKF is associated with anemia in PD patients independent of ESA dose and eEPO concentration. Trial registration: UMIN000018902