Erythropoiesis‐stimulating agent hyporesponsiveness was associated with worse survival of hemodialysis patients independent of the serum ferritin level

Abstract Introduction Ferritin level and erythropoiesis‐stimulating agent (ESA) responsiveness are each associated with hemodialysis patient survival. We assessed interrelationships between these two vs. survival. Methods Patients in the Japan Dialysis Outcomes and Practice Patterns Study Phases 4–6 (2009–2018) were included. All‐cause mortality associations were assessed with progressive adjustment to evaluate covariate influence. Results During follow‐up (median 2.6 years), 773 of 5154 patients died. After covariate adjustment, the mortality hazard ratio (HR) was 0.99 (95% CI: 0.81, 1.20) for low serum ferritin and 1.12 (CI: 0.89, 1.41) for high serum ferritin. By contrast, mortality risk with elevated ESA resistance index (ERI) persisted after covariate adjustment (HR 1.44, CI 1.17–1.78). The serum ferritin and ERI interaction was not significant; p > 0.96 across all models. Conclusions Japanese hemodialysis patients with high ERI experienced worse survival independent of serum ferritin levels, highlighting the importance of identifying and mitigating ESA hyporesponsiveness among dialysis patients.