Naturally occurring higher hemoglobin concentration does not increase mortality among hemodialysis patients

A small percentage of hemodialysis patients maintain higher hemoglobin concentrations without transfusion or erythropoietic therapy. Because uncertainty exists regarding the effects of higher hemoglobin concentration on mortality and quality of life among hemodialysis patients, studying this group of patients with sufficient endogenous erythropoietin may provide additional insights. The prospective, observational Dialysis Outcomes and Practice Patterns Study provides an opportunity to investigate this group. Among 29,796 patients in 12 nations, 545 (1.8%) maintained hemoglobin concentrations >12 g/dl for 4 months without erythropoietic support. This subset tended to be male, to have a longer duration of end-stage renal disease, and to not dialyze via a catheter. Cystic disease as the underlying cause of renal failure was over-represented in this group but was present in only 25%. Lung disease, smoking, and cardiovascular disease were associated with increased likelihood of naturally higher hemoglobin concentration. Quality-of-life scores were not higher among this subset compared with the other patients. Unadjusted mortality risk for patients with hemoglobin >12 g/dl and no erythropoietic therapy was lower than for the other patients, but after thorough adjustment for case mix, there was no difference between groups (relative risk, 0.98; 95% CI 0.80 to 1.19). These data show that naturally occurring hemoglobin concentration >12 g/dl does not associate with increased mortality among hemodialysis patients.