BACKGROUND The Berlin polytrauma definition (BPD) was established to identify multiple injury patients with a high risk of mortality. The definition includes injuries with an Abbreviated Injury Scale score of >= 3 in >= 2 body regions (2AIS >= 3) combined with the presence of >= 1 physiological risk factors (PRFs). The PRFs are based on age, Glasgow Coma Scale, hypotension, acidosis, and coagulopathy at specific cutoff values. This study evaluates and compares the BPD with two other multiple injury definitions used to identify patients with high resource utilization and mortality risk, using data from the Dutch National Trauma Register (DNTR). METHODS The evaluation was performed based on 2015 to 2018 DNTR data. First, patient characteristics for 2AIS >= 3, Injury Severity Score (ISS) of >= 16, and BPD patients were compared. Second, the PRFs prevalence and odds ratios of mortality for 2AIS >= 3 patients were compared with those from the Deutsche Gesellschaft fur Unfallchirurgie Trauma Register. Subsequently, the association between PRF and mortality was assessed for 2AIS >= 3-DNTR patients and compared with those with an ISS of >= 16. RESULTS The DNTR recorded 300,649 acute trauma admissions. A total of 15,711 patients sustained an ISS of >= 16, and 6,263 patients had suffered a 2AIS >= 3 injury. All individual PRFs were associated with a mortality of >30% in 2AIS >= 3-DNTR patients. The increase in PRFs was associated with a significant increase in mortality for both 2AIS >= 3 and ISS >= 16 patients. A total of 4,264 patients met the BPDs criteria. Overall mortality (27.2%), intensive care unit admission (71.2%), and length of stay were the highest for the BPD group. CONCLUSION This study confirms that the BPD identifies high-risk patients in a population-based registry. The addition of PRFs to the anatomical injury scores improves the identification of severely injured patients with a high risk of mortality. Compared with the ISS >= 16 and 2AIS >= 3 multiple ...