The primary objective was to predict bleeding after cardiac surgery with machine learning using the data from the ANZSCTS (Australia New Zealand Society of Cardiac and Thoracic Surgeons) Cardiac Surgery Database, cardiopulmonary bypass perfusion database, ICU (intensive care unit) database and laboratory results.

We obtained surgical, perfusion, ICU and laboratory data from a single Australian tertiary cardiac surgical hospital from February 2015 to March 2022 and included 2000 patients undergoing cardiac surgery. We trained our models to predict either the Papworth definition or Dyke et al.’s universal definition of perioperative bleeding. Our primary outcome was the performance of our machine learning algorithms using sensitivity, specificity, positive and negative predictive values, accuracy, AUROC (area under receiver operating characteristics curve) and AUPRC (area under precision recall curve).

Of the 2000 patients undergoing cardiac surgery, 13.3% (226/2000) had bleeding using the Papworth definition and 17.2% (343/2000) had moderate to massive bleeding using Dyke et al.’s definition. The best performing model based on AUPRC was the Ensemble Voting Classifier model for both Papworth (AUPRC 0.310, AUROC 0.738) and Dyke definitions of bleeding (AUPRC 0.452, AUROC 0.797).

Machine learning can incorporate routinely collected data from various datasets to predict bleeding after cardiac surgery.