BackgroundThere is limited data showing that early treatment for anemia could prolong renal survival in non-dialysis chronic kidney disease (CKD) patients. We therefore investigated the relationship between hemoglobin (Hb) levels at initiation of epoetin beta therapy and renal outcome in non-dialysis CKD patients with anemia.MethodsIn this prospective, multi-center, observational study, non-dialysis CKD patients with anemia who were naïve to erythropoiesis-stimulating agents (ESAs) were divided into three groups based on their Hb levels at initiation of epoetin beta therapy (Group I: 10 ≤ Hb < 11 g/dL, Group II: 9 ≤ Hb < 10 g/dL, and Group III: Hb < 9 g/dL). The primary endpoint was time to first occurrence of any renal event. For the primary analysis, an inverse probability weighted Cox regression model was used to adjust time-dependent selection bias in the artificially censored data.ResultsA total of 1113 patients were eligible for primary endpoint analysis. Risk of renal events was significantly higher in Group III compared with Group I (HR, 2.52; 95 % CI, 1.98–3.21; P < 0.0001); although not significant, the risk was also higher in Group II compared with Group I (HR, 1.48; 95 % CI, 0.91–2.40; P = 0.11).ConclusionInitiation of ESA therapy when Hb levels decreased below 11 g/dL but not below 10 g/dL could be more effective at reducing the risk of renal events in non-dialysis CKD patients with anemia compared with initiation of ESA therapy at below 9 g/dL or even 10 g/dL.