Assessment of Interprofessional Trauma Team Performance and Cohesion During a Civil‐Military Large‐Scale Live Simulation Exercise—A Cross‐Sectional Study

Background Large‐scale civil‐military simulation exercises allow interprofessional trauma teams practice leadership, communication, and decision‐making under high stress; however, evidence on their contribution to multinational interoperability is limited. We assessed trauma‐team performance and cohesion during a multinational live simulation and identified barriers and enablers of interoperability. Materials and Methods This prospective cross‐sectional observational study was conducted during NATO Vigorous Warrior 2024 across eight Role 2 hospitals in Hungary. Trauma teams ( n = 75) from nine nations managed simulated major trauma casualties. Performance was evaluated using the Non‐Technical Skills for Surgeons (NOTSS) and Team Emergency Assessment Measure (TEAM) frameworks. Four expert assessors made structured observations, and members completed post‐scenario self‐assessments; team and assessor ratings were compared descriptively. Results Teams rated their overall performance more favorably than assessors across all domains: overall performance was rated excellent by 57% of members versus 25% of assessors, who rated 25% of teams poor or below average. Discrepancies were greatest for leadership clarity, structured communication, and role allocation. Designated leadership, clear chains of command, and organized equipment were associated with better decision‐making and task completion. Multinational composition enriched problem‐solving but created communication barriers, tensions, and documentation inconsistencies; absent standardized debriefing further limited structured learning. Conclusions Leadership clarity, structured communication, and psychological safety underpin effective multinational trauma teamwork. The perceived‐observed performance gap, which may reflect self‐assessment leniency and assessor stringency (“hawk‐dove” effect), indicates scope for calibration through structured feedback. Standardized training frameworks, harmonized resuscitation protocols, and structured debriefing are needed to improve interoperability and readiness across civil‐military trauma systems.