Large between-center differences in outcome after moderate and severe traumatic brain injury in the international mission on prognosis and clinical trial design in traumatic brain injury (IMPACT) study.

Background: Differences between centers in patient outcome after traumatic brain injury are of importance for multicenter studies and have seldom been studied.

Objective: To quantify the differences in centers enrolling patients in randomized clinical trials (RCTs) and surveys.

Methods: We analyzed individual patient data from 9578 patients with moderate and severe traumatic brain injury enrolled in 10 RCTs and 3 observational studies.