Invited Commentary

Abstract

Dr Ranucci and colleagues present a robust and timely analysis on the utility of preoperative severe anemia in modeling mortality after adult cardiac surgery [1Ranucci M. Di Dedda U. Castelvecchio S. Menicanti L. Frigiola A. Pelissero G. Impact of preoperative anemia on outcome in adult cardiac surgery: a propensity-matched analysis.Ann Thorac Surg. 2012; 94: 1134-1142Abstract Full Text Full Text PDF PubMed Scopus (99) Google Scholar]. The authors recognize a substantial gap in cardiac surgery prediction modeling for mortality in both the United States (Society for Thoracic Surgeons and the Northern New England Cardiovascular Disease Study Group [NNE]) and Europe (EuroScore): severe anemia at the presentation for cardiac surgery. Propensity matching was used to retrospectively balance patients to treatment allocations; in this analysis, patient and operative risk factors were essentially balanced to reduce confounding, including perfusion characteristics (duration of cardiopulmonary bypass and temperature on bypass) and calculated EuroSCORE. With a well-balanced propensity-matched group of patients, a convincing case was made for the addition of severe anemia, defined as a baseline hematocrit below 30%, to standing cardiac surgery preoperative mortality models. Patients with severe anemia had nearly double the operative mortality rate of patients with moderate or no anemia and were more likely to experience other adverse events, including exposure to packed red blood cells, prolonged mechanical ventilation, and intensive care unit days. Most importantly, the authors evaluate the utility of preoperative severe anemia on the standing cardiac surgery models, including the EuroScore and NNE preoperative mortality models. The authors discovered that although the addition of severe anemia to these models did not demonstrate a significant improvement in the model's ability to predict death, it did provide a clinically meaningful improvement in the model performance in estimating mortality. In other words, the absence of severe anemia in the models underestimated the true (observed) death rate, whereas the addition of severe anemia improved each model's performance to more accurately predict mortality. Therefore, the analysis presented here is a call to both the United States and the European societies to evaluate the utility and clinical significance of severe anemia in the existing preoperative mortality models. Meanwhile, efforts should be taken to determine the presence of severe anemia before surgery; improve a patient's baseline hematocrit before surgery (when possible, without the use of transfusion) to reduce the risk of death, adverse events, and transfusions; and better incorporate patient decision-making based on more accurate estimations of the risks and benefits of surgery. In some cases, clinicians may need to consider delayed or deferred surgery for patients with severe anemia (hematocrit below 30%). Impact of Preoperative Anemia on Outcome in Adult Cardiac Surgery: A Propensity-Matched AnalysisThe Annals of Thoracic SurgeryVol. 94Issue 4PreviewPreoperative anemia is not considered an operative mortality risk factor by the majority of the risk stratification tools used in cardiac surgery. However, retrospective studies have found associations between preoperative anemia and morbidity and mortality in cardiac operations. The present study compares the postoperative outcome of a group of moderate-to-severe anemic patients with a propensity-matched group of nonanemic patients undergoing cardiac operations. Full-Text PDF