AIS > 2 in at least two body regions: a potential new anatomical definition of polytrauma

Background: The term ‘polytrauma’ lacks a universally accepted, validated definition. In clinical trials the commonly applied injury severity based anatomical score cut-offs are ISS > 15, ISS > 17 and a recently recommended AIS > 2 in at least two body regions (2 × AIS > 2). Purpose: To compare the outcomes of clinically defined polytrauma patients with those defined based on anatomical scores. Material and methods: A prospective observational study on all trauma team activation patients over a 7-month period presenting at a level-1 trauma centre were included in the study. The prospective data collection included AIS in each body region, ISS, ICU length of stay (LOS), multiple organ failure (MOF) and mortality. Results: 336 patients met inclusion criteria (age: 41 ± 20, 74% male, ISS: 15 ± 11, NISS: 19 ± 15, MOF: 3%, mortality: 4%, 25% ICU admission). ISS > 15: 13 deaths (10%), 71 (54%) required ICU admission and 10 (8%) developed MOF. ISS > 17 captured 11 deaths (11%), with 63 (62%) requiring ICU admission and 10 (10%) developing MOF. Defining as (2 × AIS > 2): 8 deaths (13% of the group), with 43 patients requiring ICU admission (67%) and 9 (14%) developing MOF. When examining the performance of these three approaches, the ISS > 15 and the ISS > 17 captured statistically the same amount of clinically defined polytrauma patients (p = 0.4106), while the 2 × AIS > 2 definition captured significantly more polytrauma patients than ISS > 15 (p = 0.0251) and ISS > 17 (p = 0.0019). Conclusion: 2 × AIS > 2 captured the greatest percentage of the worst outcomes and significantly larger % of the clinically defined polytrauma patients. 2 × AIS > 2 has higher accuracy and precision in defining polytrauma than ISS > 15 and ISS > 17. This simple, retrospectively also reproducible criteria warrants larger scale validation