Factors related to erythropoietin hypo-responsiveness in patients on chronic peritoneal dialysis

Background The present study was aimed at investigating the factors related to hypo-responsiveness to erythropoietin in patients on chronic peritoneal dialysis (PD). Methods We studied 44 patients with end-stage renal disease who had been on PD for more than 6 months and on erythropoietin (EPO) ≥6,000 U/week for more than 3 months. We expressed EPO resistance index (ERI) as weekly EPO dose per hematocrit (Hct) per body weight. The dose of EPO was titrated to maintain a target Hct level between 33% and 36%. Patients were divided into two groups according to weekly EPO dose. We compared the various factors in those two groups and, by using correlation and linear regression analysis, investigated factors that might predict EPO resistance. Results There were 13 patients in the EPO <150 U/kg per week group and 31 patients in the EPO ≥150 U/kg per week group. Among those 31 patients, there were five patients on EPO ≥300 U/kg per week. Compared to the EPO <150 U/kg per week group, the EPO ≥150 U/kg per week group had a lower normalized protein catabolic rate (nPCR), lower level of serum albumin and higher C-reactive protein (CRP). Correlation analysis showed that the ERI had a statistically significant correlation with CRP (r = 0.303, P < 0.05), serum albumin (r = −0.26, P < 0.05), parathyroid hormone (PTH) (r = −0.307, P < 0.05) and nPCR (r = −0.259, P < 0.05). These results show that CRP, serum albumin, PTH and nPCR are factors related to hypo-responsiveness. Multiple stepwise linear regression analysis showed that CRP was the most important independent predictor of EPO hypo-responsiveness. Conclusion CRP, serum albumin, nPCR and PTH are factors related to hypo-responsiveness. Inflammation contributes significantly to EPO hypo-responsiveness.