Transfusion indication predictive score: A proposed risk stratification score for perioperative red blood cell transfusion in cardiac surgery

Background and Objectives: Red blood cell transfusion is known to be associated with increased morbidity and mortality in cardiac surgery. This study was performed to derive a score to predict that risk in our patients. Materials and Methods: Clinical details of patients who underwent cardiac surgery at the Sultan Qaboos University Hospital over 5 years were reviewed. We used univariable and multivariable logistic regression to develop the score, the Hosmer-Lemeshow test for calibration, the receiver operator curve for discrimination and the bootstrap procedure for internal validation. Results: The sample included 413 patients. The following were found to be statistically significant transfusion predictors (score given): cerebrovascular disease (4), use of aspirin or clopidogril within 7 days of surgery (3), non-elective surgery (2), haematocrit <35% (2), glucose-6-phosphate dehydrogenase (G6PD) deficiency (2), use of cardiopulmonary bypass (2), age > 60 years (1), diabetes mellitus (1) and male gender (-2). We classified the observations into three groups: group 1 with total score of <2, group 2 with total score of 2-5 and group 3 with total score of >5. The calculated probabilities of receiving transfusion were 42%, 63% and 91% for groups 1, 2 and 3 respectively. Conclusion: We derived a simple score that can be utilized to assess the need of blood transfusion in patients undergoing cardiac surgery. We are the first to report G6PD deficiency and history of cerebrovascular disease as predictors. We recommend prospective external validation of the proposed score on a larger cohort of patients.