Blood transfusion requirement during liver transplantation is an important risk factor for mortality

Background: Blood loss during liver transplantation is not incorporated into the dominant models for post-transplant survival. Our objective was to investigate blood transfusion requirement as a risk factor for mortality after liver transplantation, and to further analyze risk factors for intraoperative blood transfusion requirement and hepatectomy time. Study Design: We conducted a retrospective analysis of 233 consecutive liver transplant recipients over a span of 3 years by a single experienced surgeon. Mean follow-up was 2.5 years. Independent risk factors for patient survival after liver transplantation were identified using Cox proportion hazard regression. Independent risk factors for intraoperative blood transfusion requirement and hepatectomy time were identified using logistic regression. Results: Two factors were identified as significant predictors in multivariate analysis for survival after liver transplantation: hepatocellular carcinoma (hazard ratio [HR] 1.9, 95% CI 1.1 to 3.2) and intraoperative blood transfusion requirement per unit (HR 1.01, 95% CI 1.0 to 1.02). Threshold analysis revealed that intraoperative blood transfusion volume ≥28 units or 85^th percentile (HR 2.5, 95% CI 1.3 to 4.7) was a significant risk factor for patient survival. Four covariates were identified as significant risk factors for intraoperative blood requirement: warm ischemia time (odds ratio [OR] 1.12, 95% CI 1.06 to 1.18), bilirubin (OR 1.04, 95% CI 1.02 to 1.08), previous surgery (OR 1.7, 95% CI 1.02 to 2.9), and hepatectomy time (OR 1.01, 95% CI 1.00 to 1.02). The only risk factor for prolonged hepatectomy time was previous major abdominal surgery (OR 4.0, 95% CI 1.7 to 9.5). Conclusions: Intraoperative blood transfusion requirement is an important risk factor for mortality after liver transplantation. The strongest risk factors for intraoperative blood transfusion requirement are warm ischemia time and bilirubin levels. Intraoperative blood loss and its risk factors should be incorporated into models to predict survival after liver transplantation.