Beyond Successful Training: First Battlefield Use of Tactical Combat Casualty Care for All Service Members by Mobilized Personnel

BACKGROUND: Tactical Combat Casualty Care for All Service Members (TCCC-ASM) aims to prepare military personnel to provide self-aid and buddy aid in combat. However, the extent to which acquired TCCC-ASM skills are personally applied during real combat remains poorly understood. This study evaluated the influence of first combat experience on the practical application of TCCC-ASM among mobilized personnel during the Russo-Ukrainian War. METHODS: A multicohort observational study was conducted between August 2022 and May 2026. Data from 5 independent cohorts were integrated, including educational assessments, structured surveys, operational observations, medical evacuation records, and rehabilitation data. The primary endpoint was the reported or directly observed application of TCCC-ASM skills in identified TCCC-relevant combat situations. Personal application of acquired TCCC-ASM skills was quantified using the Training-to-Performance Index (TP-index), a descriptive measure developed specifically for this study. RESULTS: A total of 1,961 participants were included. Although all participants successfully completed TCCC-ASM training, 539 of 1,082 service members with combat experience (50%) contributed 1 identified index TCCC-relevant combat situation. Among 327 wounded personnel, self-aid was performed by 71 individuals (22%), whereas in the remaining 78%, the corresponding interventions were performed by other personnel through buddy aid. The TP-index was 71/539 (0.13; 95% confidence interval, 0.10-0.16), indicating limited personal application of acquired TCCC-ASM skills across identified TCCC-relevant combat situations. Major barriers to self-aid included severe pain, inability to recall procedures, panic reactions, and limited visibility; prolonged evacuation was also frequently encountered. First combat experience was associated with reassessment of training relevance and increased perceived need for refresher training. CONCLUSIONS: A measurable gap exists between successful completion of TCCC-ASM training and personal application of acquired skills in combat. This phenomenon, defined as the Training-to-Performance Gap, highlights the limitations of relying solely on educational outcomes when evaluating military medical training. The proposed TP-index provides a descriptive measure of personal application of acquired TCCC-ASM skills in combat and, together with the observed Training-to-Performance Gap, supports consideration of refresher training following first combat experience.