Patrick Lawler and colleagues have performed a systematic review of cohort studies and randomized clinical trials that have evaluated the association of anemia and mortality in patients with acute coronary syndrome. The authors identified 27 studies with 233,000 patients. Anemia was present in 19% of patients and associated with 50% increase in adjusted mortality. Most of the studies evaluated the admission hemoglobin concentration and there are very limited data (see appendix E) describing the risk associated with different hemoglobin concentrations. Unfortunately, the risk associated with the nadir hemoglobin concentration is not available in most of the studies summarized in this report. I strongly agree with the authors that randomized clinical trials are needed to evaluate if correction of anemia improves outcomes.

– Jeffrey L. Carson