Lower hemoglobin concentration decreases time to death in severely anemic patients for whom blood transfusion is not an option.

Abstract

Anemia in patients who decline transfusion has been associated with increased morbidity and mortality. We hypothesized that the time to death decreases with increasing severity of anemia in patients for whom transfusion is not an option. With institutional review board approval, a retrospective review of registered adult blood refusal patients with at least one hemoglobin (Hb) value of 12.0 g/dL or less during hospital admission at a single institution from January 2004 to September 2015 was performed. The association of nadir Hb category and time to death (all-cause 30-day mortality) was determined using Kaplan-Meier plots, log rank tests, and Cox proportional hazard models. We investigated if there was a nadir Hb level between the values of 5.0 and 6.0 g/dL at which mortality risk significantly increased and then categorized nadir Hb by the traditional cut points and the newly identified "critical" cut point. The study population included 1,011 patients. The Cox proportional hazard models showed a more than 50% increase in hazard of death per 1 g/dL decrease in Hb (adjusted hazard ratio [confidence interval], 1.55 [1.40-1.72]; p < 0.001). A Hb value of 5.0 g/dL was identified as defining "critical anemia." We found a strong association between anemia severity level and mortality (p < 0.001). Time to death was shorter (median, 2 days) in patients with critical anemia than in those having higher Hb (median time to death of 4 or 6 days, in severe or moderate anemia). In anemic patients unable to be transfused, critical anemia was associated with a significantly and clinically important reduced time to death. Prognostic, level III.