Prehospital Prediction of Acute Coagulopathy of Trauma

Thesis (Master's)--University of Washington, 2015Abnormal clotting function afflicts up to 30% of severely-injured patients by the time they reach the emergency department and is associated with an increased risk of mortality, venous thromboembolism, and multiple organ failure. Prehospital identification of patients with acute coagulopathy of trauma (ACT), defined as an INR >1.5 on emergency department arrival, will facilitate study of the syndrome’s mechanisms and targeted treatment. We developed a prehospital prediction model for ACT — the Prediction of Acute Coagulopathy of Trauma (PACT) score — using data from severely-injured trauma patients enrolled in a population-based, multicenter trauma registry. Construction of a parsimonious multivariable logistic regression model employed a best-subsets model selection approach and multiply imputed data to minimize bias. Predictors in the final model included elevated shock index, older age, prehospital cardiopulmonary resuscitation or endotracheal intubation, lower prehospital Glasgow Coma Score, and injury mechanism not related to driving or riding a motorcycle, bicycle or in a motor vehicle. After internal validation of our model using bootstrap techniques, we externally validated the PACT score in a separate cohort of severely-injured, transfusion-requiring trauma patients admitted to the ICU of a level 1 trauma center. The PACT score demonstrated good discrimination (AUROC 0.80, 95% CI 0.72-0.88) and calibration (Hosmer-Lemeshow goodness-of-fit statistic p=0.37). At a threshold of ≥200, the PACT score’s sensitivity and specificity for ACT were 73% and 72%, respectively. By comparison, a previously published prehospital ACT prediction score had lower discrimination (AUROC 0.70, 95% CI 0.60-0.80, p=0.038 for comparison to PACT score) with evidence of inadequate calibration (Hosmer-Lemeshow goodness-of-fit statistic p=0.036). In summary, our prediction score uses routinely-available and objective prehospital data to identify patients at increased risk of ACT. The PACT score could facilitate subject selection for studies of ACT’s targeted treatment