Abstract 15887: Anemia, Red Blood Cell Transfusion, and Mortality in Patients With Acute Coronary Syndromes: A Meta-Analysis and Systematic Review
Background - Despite the high prevalence of anemia among patients presenting with acute coronary syndromes (ACS), the impact of anemia on their outcomes is incompletely understood. Furthermore, the role of packed red blood cell (PRBC) transfusion in ACS patients who present with anemia or who develop it in-hospital is unclear, and there is considerable equipoise as to which hemoglobin (HgB) thresholds should prompt PRBC transfusion.
Methods - We performed two systematic literature searches of MEDLINE to identify cohort studies and retrospective analyses of randomized controlled trials examining the association between anemia and mortality among patients with ACS (Search 1) and the impact of PRBC transfusion among patients with ACS (Search 2). Anemia data were aggregated using random-effects meta-analysis models.
Results - Search 1 identified 22 studies which met our inclusion criteria with a mean follow-up time of 21.9 months (171,014 patients; 30,854 with anemia). Anemic patients were older, with generally a higher prevalence of comorbidities, including a history of major bleeding. The crude mortality risk among anemic patients was significantly higher (relative risk [RR] = 1.97; 95% CI = 1.58, 2.47), as was the risk of reinfarction (RR = 1.39; 95% CI = 1.00, 1.94). Adjusted hazard ratios reported in individual studies suggest that this increased risk is independent of potential confounders. Search 2 identified 11 studies (290,847 patients). When anemia was present at baseline or developed in-hospital, PRBC transfusion was associated with a higher overall risk of mortality. However, when patients were stratified by nadir hemoglobin, PRBC transfusion was associated with a decreased risk of death when undertaken at nadir HgB < 8.0 g/dL, and an increased risk when undertaken at nadir HgB > 10.0 g/dL. All studies were observational in nature, and although adjusted risks were studied, the possibility for confounding remains.
Conclusions - Anemia in patients with ACS is associated with a nearly two-fold increased risk of mortality and a 39% increased risk of reinfarction. These data suggest a favorable effect of PRBC transfusion when nadir HgB < 8.0 g/dL, but suggest neutral effect or even harm at higher transfusion thresholds.
- © 2011 by American Heart Association, Inc.