Anemia in hemodialysis patients: variables affecting this outcome predictor

Despite the prevalent use of recombinant human erythropoietin (rhEPO), anemia is a frequent finding in hemodialysis patients. The goal of this study was to evaluate the impact of anemia on patient survival and characterize the determinants of hematopoiesis that may be amenable to therapeutic manipulation to enhance rhEPO responsiveness and reduce death risk. Patient characteristics and laboratory data were collected for 21,899 patients receiving hemodialysis three times per week in dialysis centers throughout the United States in 1993. Hemoglobin concentrations (Hb) < or =80 g/L were associated with a twofold increase in the odds of death (odds ratio = 2.01; P = 0.001) when compared with Hb 100 to 110 g/L. No improvement in the odds of death was afforded for Hb >110 g/L. Using multiple linear regression, variables of rhEPO administration (rhEPO dose and percentage of treatments that rhEPO was administered), variables of iron status (serum iron, transferrin saturation, and ferritin), variables of nutritional status (serum albumin and creatinine concentration), and the dose of dialysis (urea reduction ratio) were found to be significantly associated with hemoglobin concentration (P < 0.001). Age, race, and gender were also found to be significantly associated with hemoglobin concentrations (P < 0.001). From this report, the following conclusions may be made. (1) Anemia may be predictive of an increased risk of mortality in some hemodialysis patients. (2) Hemoglobin concentrations > 110 g/L are not associated with further improvements in the odds of death. (3) Laboratory surrogates of iron stores, nutritional status, and the delivered dose of dialysis are predictive of hemoglobin concentration. Whether manipulation of the factors that improve anemia will also enhance the survival of patients on hemodialysis is unknown and should be evaluated by prospective, interventional studies.