Impact of anemia on outcome in critically ill patients with severe acute renal failure.

Abstract

To evaluate the prognostic value of hemoglobin levels in critically ill patients with acute renal failure (ARF) requiring dialysis. A prospective observational cohort study in two adult medical ICUs. 206 consecutive patients with ARF who required dialysis. Overall 28-day mortality was 48%. At ICU admission mean hemoglobin level was 9.1+/-2.1 g/dl. By ROC curve analysis the threshold value of hemoglobin with the highest sensibility/specificity was 9 g/dl. At baseline 63% of patients had anemia, defined as initial hemoglobin below 9 g/dl. Kaplan-Meier analysis showed that these patients had lower survival rate than those with hemoglobin above 9 g/dl. By multivariable analysis three factors were independently associated with 28-day death: hemoglobin lower than 9 g/dl (adjusted odds ratio 2.4, 95% CI 1.1-5.2), age, and SOFA score. Based on age and SOFA a matched cohort analysis of 67 pairs of ARF patients with or without anemia found similar results regarding the negative impact of anemia on outcome. Finally, a multivariable logistic regression analysis on matched cohort identified hemoglobin level below 9 g/dl (adjusted odds ratio 1.32, 95%CI 1.15-1.46), continuous renal replacement therapy, and vasoactive therapy as independent predictors of 28-day death. These results suggest that initial hemoglobin level could be helpful in identifying patients with ARF requiring dialysis at high risk of death.