Helicopter versus GROUND emergency medical services in mountainous trauma care: a comparative cohort study on time efficiency, golden hour achievement, and clinical outcomes in the Qinba region

To compare the time efficiency and clinical outcomes of helicopter emergency medical services (HEMS) versus ground emergency medical services (GROUND) for severe trauma in the mountainous Qinba region, with a focus on achieving the "golden hour" and its impact on patient prognosis. This single-center retrospective cohort study included severe trauma patients (Injury Severity Score [ISS] ≥ 16) transported by HEMS or GROUND between January 2018 and September 2025. Propensity score matching (1:1) w