Prevalence and prognosis of mild anemia in non-dialysis chronic kidney disease: a prospective cohort study in outpatient renal clinics

Abstract

Background/aims: we evaluated prevalence and prognosis of mild anemia, defined as Hb (g/dl) 11-13.5 in males and 11-12 in females, in a prospective cohort of stage 3-5 chronic kidney disease (CKD) patients.

Methods: we enrolled 668 consecutive patients in 25 renal clinics during 2003. Patients with frank anemia (Hb <11 or erythropoiesis-stimulating agents) at enrolment were excluded. Mild anemia was evaluated at two visits planned with an interval of 18 ± 6 months to identify four categories: no anemia at both visits, mild anemia at visit 1 resolving at visit 2 (RES), mild anemia persisting at both visits (PER), and progression from no anemia or mild anemia at visit 1 to mild or frank anemia at visit 2 (PRO).

Results: mild anemia was present in 41.3% at visit 1 and 34.1% at visit 2. We identified PER in 22% patients, RES in 10%, and PRO in 26%. In the subsequent 40 months, 125 patients developed end-stage renal disease (ESRD) and 94 died. At competing risk model, PER predicted ESRD (hazard ratio, HR, 1.82, 95% confidence interval, CI, 1.01-3.29) while PRO predicted both ESRD (HR 1.81, 95% CI 1.02-3.23) and death (HR 1.87, 95% CI 1.04-3.37).

Conclusion: in non-dialysis chronic kidney disease, mild anemia is prevalent and it is a marker of risk excess when persistent or progressive over time.