Higher hemoglobin levels using darbepoetin alfa and kidney outcomes in advanced chronic kidney disease without diabetes: a prespecified secondary analysis of the PREDICT trial

BACKGROUND: In the primary analysis of the PREDICT trial, a higher hemoglobin target (11–13 g/dl) with darbepoetin alfa did not improve renal outcomes compared with a lower hemoglobin target (9–11 g/dl) in advanced chronic kidney disease (CKD) without diabetes. Prespecified secondary analyses were performed to further study the effects of targeting higher hemoglobin levels on renal outcomes. METHODS: Patients with an estimated glomerular filtration rate (eGFR) 8–20 ml/min/1.73 m(2) without diabetes were randomly assigned 1:1 to the high- and low-hemoglobin groups. The differences between the groups were evaluated for the following endpoints and cohort sets: eGFR and proteinuria slopes, assessed using a mixed-effects model in the full analysis set and the per-protocol set that excluded patients with off-target hemoglobin levels; the primary endpoint of composite renal outcome, evaluated in the per-protocol set using the Cox model. RESULTS: In the full analysis set (high hemoglobin, n = 239; low hemoglobin, n = 240), eGFR and proteinuria slopes were not significantly different between the groups. In the per-protocol set (high hemoglobin, n = 136; low hemoglobin, n = 171), the high-hemoglobin group was associated with reduced composite renal outcome (adjusted hazard ratio: 0.64; 95% confidence interval: 0.43–0.96) and an improved eGFR slope (coefficient: + 1.00 ml/min/1.73 m(2)/year; 95% confidence interval: 0.38–1.63), while the proteinuria slope did not differ between the groups. CONCLUSIONS: In the per-protocol set, the high-hemoglobin group demonstrated better kidney outcomes than the low-hemoglobin group, suggesting a potential benefit of maintaining higher hemoglobin levels in patients with advanced CKD without diabetes. CLINICAL TRIAL REGISTRATION: Clinicaltrials.gov (identifier: NCT01581073). SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s10157-023-02362-w.