Patients with chronic kidney disease (CKD) commonly develop anemia. However, there are few data available on the incidence of anemia in nephrology settings. The risks of adverse outcomes associated with new-onset are also not well known.
Robert Minutolo, MD, PhD, and colleagues performed a pooled analysis of three observational cohort studies including 1031 non-anemia patients with CKD with estimated glomerular filtration rate (eGFR) <60 mL/min/1.73 m2 who were regularly followed in renal clinics. Results of the analysis were reported in the Clinical Kidney Journal [2022;15(6):1120-1128].
The researchers estimated the incidence of mild anemia (defined as hemoglobin 11-12 g/dL in women and 11-13 g/dL in men) and severe anemia (defined as hemoglobin <11 or use of erythropoiesis-stimulating agents) during a 3-year period. They then estimated the risk of end-stage kidney disease (ESKD) and all-cause death associated with new-onset mild and severe anemia.
Mean age of the overall cohort was 63 years, 60% were male, and 20% had diabetes. Mean eGFR was 37 mL/min/1.73 m2 and median proteinuria was 0.4 g/day. The incidence of mild anemia was 13.7 per 100 patient-years and the incidence of severe anemia was 6.2 per 100 patient-years.
Predictors of either mild or severe anemia were diabetes, lower hemoglobin, higher serum phosphate, eGFR 30 mL/min/1.73 m2, and proteinuria >0.50 g/day. Male sex, moderate CKD (eGFR 30-44 mL/min/1.73 m2), and moderate proteinuria (0.15-0.50 g/day) predicted mild anemia but not severe anemia.
The incidence of anemia increased progressively with CKD stages (from 8.77 to 76.59 per 100 patient-years) and with proteinuria category (from 13.99 to 25.02 per 100 patient-years. Median follow-up was 3.1 years, during which 232 patients progressed to ESKD and 135 died. Compared with patients without anemia, patients with mild anemia had a higher adjusted risk of ESKD (hazard ratio [HR], 1.42; 95% confidence interval [CI], 1.02-1.98) and all-cause death (HR, 1.55; 95% CI, 1.04-2.32). There was a greater risk of ESKD and death with severe anemia (HR, 1.73; 95% CI, 1.20-2.51 and HR, 1.83; 95% CI, 1.05-3.19, respectively).
In conclusion, the researchers said, “New-onset anemia is frequent, particularly in patients with more severe renal damage and in those with diabetes mellitus. The occurrence of anemia, even of a mild degree, is associated with mortality risk and faster progression towards ESKD.”