All levels of trauma care performed equally on in-hospital mortality among severely injured patients (MAIS ≥ 3), although patients admitted to the level I TC were more severely injured. Subgroups of patients by body region or ISS, with a survival benefit or more favorable clinical outcome measures were not identified. Subgroups analysis on clinical outcome measures across different levels of trauma care in an inclusive trauma network is too simplistic if subgroups are based on injuries in specific body region or ISS only.