Impact of hemoglobin levels on renal and non-renal clinical outcomes differs by chronic kidney disease stages: the Gonryo study

Background

Anemia greatly affects the development of renal and cardiovascular outcomes in chronic kidney disease (CKD) patients. However, the impact based on CKD stage remains unclear.

Methods

We prospectively followed 2,602 Japanese CKD patients under the care of nephrologists. CKD was defined according to cause, estimated glomerular filtration rate <60 mL/min, and/or proteinuria. Patient outcomes primary end-points: cardiovascular events (CVEs), all-cause mortality, and end-stage kidney disease (ESKD) requiring renal replacement therapy] were assessed in association with basal hemoglobin (Hb) levels (<10, 10–12 and ≥12 g/dL), stratified by CKD stages.

Results

During follow-up, 123 patients developed CVEs, 41 died, and 220 progressed to ESKD. For stages G3, G4 and G5, ESKD frequencies were 2.8, 64.4, and 544.8 person-years, while CVEs and death were 25.6, 45.6, and 76.3 person-years, respectively. The combined endpoint rate was significantly higher in patients with Hb <10 versus Hb 10–12 g/dL, but a higher risk for CVEs and death with Hb <10 g/dL was found only in G3 hazard ratio (HR) 4.49, (95 % confidence interval (95 % CI) 2.06–9.80)]. In contrast, risk for ESKD with Hb <10 g/dL was found only in G4 HR 3.08 (95 % CI 1.40–6.79)] and G5 HR 1.43 (95 % CI 1.01–2.05)]. No increased risks with higher Hb levels were found.

Conclusion

The impact of renal anemia of Hb <10 g/dL on clinical outcomes differed by CKD stage, with a significantly high risk for CVEs and all-cause mortality in G3 and progression to ESKD in G4 and G5.