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

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).

To compare the outcomes of clinically defined polytrauma patients with those defined based on anatomical scores.

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.

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).

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.