AntiPORT: adaptation of a transfusion prediction score to an Australian cardiac surgery population

Introduction: Risk scoring systems exist to predict perioperative blood transfusion risk in cardiac surgery, but none have been validated in the Australian or New Zealand population. The ACTA-PORT score was developed in the United Kingdom for this purpose. In this study, we validate and recalibrate the ACTA-PORT score in a large national database. Methods: We performed a retrospective validation study using data from the Australian and New Zealand Society of Cardiac and Thoracic Surgeons Database between 1 September 2016 and 31 December 2018. The ACTA-PORT score was calculated using an equivalent of EuroSCORE I. Discrimination and calibration was assessed using area under the receiver operating characteristic (AUROC) curves, Brier scores, and calibration plots. ACTA-PORT was then recalibrated in a development set using logistic regression and the outcome of transfusion to develop new predicted transfusion rates, termed "AntiPORT", using AusSCORE "all procedures" as the regional equivalent of EuroSCORE I. The accuracy of these new predictions was assessed as for ACTA-PORT. Results: 30 388 patients were included in the study at 37 Australian centres. The rate of red blood cell transfusion was 33%. Discrimination of ACTA-PORT was good but calibration was poor, with overprediction of transfusion (AUROC curve, 0.76; 95% CI, 0.75-0.76; Brier score, 0.19). The recalibrated AntiPORT showed significantly improved calibration in both development and validation sets without compromising discrimination (AUROC curve, 0.76; 95% CI, 0.75-0.76; Brier score, 0.18). Conclusions: The AntiPORT is the first red cell transfusion risk scoring system for cardiac surgery patients to be validated using Australian data. It is accurate and simple to calculate. The demonstrated accuracy of AntiPORT may help facilitate benchmarking and future research in patient blood management, as well as providing a useful tool to help clinicians target these resource-saving strategies.