Background: Traumatic brain injury (TBI) has long been associated with coagulopathy; however, the time course of coagulation/fibrinolytic parameters in the acute phase of TBI remains unclear.
Objective: To analyze the time course of coagulation/fibrinolytic parameters in the acute phase of TBI and to elucidate parameter relationships to prognosis.
Methods: We retrospectively evaluated 234 patients with severe isolated TBI with initial blood samples obtained no more than 1 hour after injury. Platelet count, prothrombin time, activated partial thromboplastin time (aPTT), plasma levels of fibrinogen, and D-dimer were measured on arrival and 3, 6, and 12 hours after injury. Multivariate logistic regression analysis was performed to identify risk factors for poor prognosis at each time point.
Results: From admission to 12 hours after injury, an elevated D-dimer level was a significant negative prognostic indicator (admission: p < 0.0001; 3 hours after injury: p = 0.0005; 6 hours after injury: p = 0.005; 12 hours after injury: p = 0.0009). An upward trend of aPTT on admission and 3 hours after injury was also a significant negative prognostic indicator (admission: p = 0.0011; 3 hours after injury: p = 0.013). On multivariate logistic regression analysis which included all initial variables, independent risk factors for poor prognosis included older age (p = 0.0005), low Glasgow Coma Scale score (p < 0.0001), high Abbreviated Injury Score (p = 0.015), aPTT > 30.2 seconds (p = 0.019), and elevated D-dimer level (p = 0.0005).
Conclusion: D-dimer is the best coagulation/fibrinolytic parameter to monitor for prediction of outcome.

Time Course of Coagulation and Fibrinolytic Parameters in Patients with Traumatic Brain Injury