The association between preoperative anemia, blood transfusion need, and postoperative complications in adult cardiac surgery, a single center contemporary experience

BACKGROUND: The impact of preoperative anemia on postcardiac surgery outcomes is an area of great debate. Although several large-scale studies have been conducted, they have demonstrated conflicting results. A limited number of studies have been conducted in the Middle East. The primary aim of this study was to investigate the association between preoperative anemia and the need for blood transfusions, as well as major postoperative complications. METHODS: Adult patients who underwent cardiac surgery at King Faisal Cardiac Center in Jeddah between June 2016 and January 2020 were included in this retrospective cohort study. The study excluded patients with hereditary preoperative anemia. Among the variables studied were variables related to demographics, comorbidities, laboratory data, operation-related data, in-hospital complications, and mortality. RESULTS: The mean preoperative hemoglobin (Hb) level was 13.2 g/dL (SD ± 1.8). The overall mortality rate was 4.6%. A lower preoperative Hb level (p value = 0.016), postoperative day 1 WBC count (p-value = 0.003), and prolonged cross clamp time (p value < 0.001) were significantly associated with mortality. A lower Hb level during the preoperative period or within the first three days of surgery was associated with a higher blood transfusion requirement. However, there was no significant association between blood transfusion and postoperative complications. A multivariate stepwise logistic regression model was developed and several pre and intra operative factors were predictive of the need PRBCs transfusion after cardiac surgery (which included: older age, female gender, lower pre-operative hemoglobin and longer cardio-pulmonary bypass time), with had a predictive accuracy of around ~ 86%. CONCLUSION: Based on our single center study, patients with preoperative lower Hb levels are at higher risk of mortality. However, blood transfusion does not seem to increase the risk of postoperative complications. Optimal utilization of blood products is an important quality metric and identification of patients at higher risk of requiring PRBCs transfusion prior to cardiac surgery can help in implementing pre or intra operative strategies to minimize the need for transfusion.