Utility of point-of-care platelet aggregation testing for transfusion prediction.

Early identification and initiation of therapy for life-threatening hemorrhage is essential to minimize patient morbidity and mortality. In primary hemostasis, platelet function is integral to reach this goal, but major hemorrhage leads to impaired platelet mechanical activation and aggregation. Current devices for measuring platelet function are cumbersome or not promptly available for clinical decision making in this setting. Within this manuscript we prospectively evaluate a novel, rapid assay utilizing measures of platelet aggregation to predict hemorrhage. In this prospective cohort study at an academic regional Level I trauma center, we included adult (> 16 years old) participants who were triaged as level I or II trauma activations. The primary exposure studied was platelet aggregation analyzed on a prototype device. The primary and secondary outcomes measured were life-threatening hemorrhage (death from hemorrhage or need for hemorrhage control procedure) and transfusion requirements of > 2 units of blood components, respectively. Standard descriptive statistics were used to characterize the cohort. Predictive outcomes were analyzed using multivariable regression to compare: (1) the platelet aggregation assay; (2) clinical parameters (systolic blood pressure, heart rate, and injury mechanism); and (3) a combined model. Of 761 patients, 482 patients met inclusion criteria for our study, 36 (7.5%) had life-threatening hemorrhage and 43 (8.9%) patients required > 2 units of blood transfusion. For life-threatening hemorrhage, platelet aggregation had an area under the curve (AUC): 0.61 (95% confidence interval [CI] 0.53-0.69); clinical parameters AUC: 0.83 (CI 0.75-0.91); and the combined model AUC: 0.85 (CI 0.79-0.92) which was not significantly improved when compared to clinical parameters alone (p = 0.32). For transfusion of > 2 units, the platelet aggregation model had AUC: 0.68 (CI 0.61-0.76); clinical parameters AUC: 0.84 (CI 0.79-0.90); and combined model AUC: 0.88 (CI 0.83-0.93), improving transfusion prediction over clinical parameters alone (p = 0.013). In a cohort of traumatically injured patients, a novel, rapid measure of platelet aggregation enhanced well-established clinical parameters to predict the need for blood transfusion but not life-threatening hemorrhage. Future work should validate the clinical utility of this technology in a larger cohort and patients with significant non-traumatic hemorrhage.