POBS-CARD, a new score of severe bleeding after cardiac surgery: construction and external validation

Introduction Bleeding after cardiac surgery leads to poor outcomes. The objective of the study was to build the PeriOperative Bleeding Score in Cardiac surgery (POBS) to predict bleeding after cardiac surgery. Methods We conducted a retrospective cohort study in two academic hospitals (2016-2019). Inclusion criteria were adult patients after cardiac surgery under cardiopulmonary bypass. Non-inclusion criteria were heart transplantation, assistance, aortic dissection, preoperative hemostasis diseases. Bleeding was defined by the Universal definition for perioperative bleeding score ≥ 2. POBS score was built using a multivariate regression (derivation cohort, one center). The performance diagnosis was assessed using the Area Under the Curve (AUC) in a validation cohort (two centers) and compare with other scores. Results 1704 patients were included in the derivation cohort, 344 (20%) with bleeding. Preoperative factors were: body mass index < 25 kg/m2 (OR:1.48[1.14-1.93]), type of surgery (redo (OR:1.76[1.07-2.82]), combined (OR:1.81[1.19-2.74]), ascendant aorta (OR:1.56[1.02-2.38])), ongoing antiplatelet therapy (single (OR:1.50[1.09-2.05]), dual (OR:2.00[1.15-3.37])), activated thromboplastin time ratio > 1.2 (OR:1.44[1.03-1.99]), prothrombin ratio < 60% (OR:1.91[1.21-2.97]), platelet count < 150 G/L (OR:1.74[1.17-2.57]) and fibrinogen < 3g/L (OR:1.33[1.02-1.73]). In the validation cohort of 597 patients, the AUC was 0.645 [0.605-0.683] and was superior to other scores (Will-bleed, Papworth, TRUST, TRACK). A threshold > 14 predicted bleeding with a sensitivity of 50% and a specificity of 73%. Conclusion POBS-Card score was superior to other scores in predicting severe bleeding after cardiac surgery. Performances remained modest, questioning the place of these scores in the perioperative strategy of bleeding-sparing.