The HAT Score—A Simple Risk Stratification Score for Coagulopathic Bleeding During Adult Extracorporeal Membrane Oxygenation

Document Type

Journal Article

Publication Date



Journal of Cardiothoracic and Vascular Anesthesia








bleeding; extracorporeal membrane oxygenation; risk stratification


Objective The study objective was to create an adult extracorporeal membrane oxygenation (ECMO) coagulopathic bleeding risk score. Design Secondary analysis was performed on an existing retrospective cohort. Pre-ECMO variables were tested for association with coagulopathic bleeding, and those with the strongest association were included in a multivariable model. Using this model, a risk stratification score was created. The score's utility was validated by comparing bleeding and transfusion rates between score levels. Bleeding also was examined after stratifying by nadir platelet count and overanticoagulation. Predictive power of the score was compared against the risk score for major bleeding during anti-coagulation for atrial fibrillation (HAS-BLED). Setting Tertiary care academic medical center. Participants The study comprised patients who received venoarterial or venovenous ECMO over a 3-year period, excluding those with an identified source of surgical bleeding during exploration. Interventions None. Measurements and Main Results Fifty-three (47.3%) of 112 patients experienced coagulopathic bleeding. A 3-variable score—hypertension, age greater than 65, and ECMO type (HAT)—had fair predictive value (area under the receiver operating characteristic curve [AUC] = 0.66) and was superior to HAS-BLED (AUC = 0.64). As the HAT score increased from 0 to 3, bleeding rates also increased as follows: 30.8%, 48.7%, 63.0%, and 71.4%, respectively. Platelet and fresh frozen plasma transfusion tended to increase with the HAT score, but red blood cell transfusion did not. Nadir platelet count less than 50×103/µL and overanticoagulation during ECMO increased the AUC for the model to 0.73, suggesting additive risk. Conclusions The HAT score may allow for bleeding risk stratification in adult ECMO patients. Future studies in larger cohorts are necessary to confirm these findings.