Impact of anemia on renal outcomes in elderly patients with chronic kidney disease: a cohort study

Abstract Background We aimed to examine the impact of anemia on the risk of further deterioration in renal function among elderly and nonelderly patients with chronic kidney disease (CKD). Methods In this retrospective cohort study, we included 1098 predialysis patients with CKD hospitalized for an educational program on CKD between January 2010 and December 2018. Patients aged < 75 years (657) were considered nonelderly, and those aged ≥ 75 years (441) were considered elderly; each category was stratified by hemoglobin level to evaluate the incidence of CKD progression: < 9.0 g/dL, 9.0–10.9 g/dL, 11.0–12.9 g/dL, and ≥ 13.0 g/dL. The study was terminated after 3 years of observation. Results CKD progression occurred in 550 and 304 patients in the nonelderly and elderly group, respectively. In the nonelderly group, multivariate Cox models revealed that an increased risk of CKD progression was observed in patients with low hemoglobin levels compared with those with hemoglobin levels of 11.0–12.9 g/dL. However, in the elderly group, adverse renal outcomes occurred at rates that did not differ significantly according to the hemoglobin level. Furthermore, we isolated patients with hemoglobin levels of 9.0–10.9 g/dL and 11.0–12.9 g/dL and analyzed the risk of renal outcomes in both nonelderly and elderly people among them. Examination of renal outcomes in 1:1 the propensity-score-matched cohort of patients with hemoglobin levels of 9.0–10.9 g/dL versus patients with levels of 11.0–12.9 g/dL yielded consistent results. Conclusions Mild anemia may be poorly associated with renal prognosis in elderly patients with CKD.