Relationship between the Injury Severity Score and the need for life-saving interventions in trauma patients in the UK

Introduction: Major trauma is the third leading cause of avoidable mortality in the UK. Defining which patients require care in a major trauma centre is a critical component of developing, evaluating and enhancing regional major trauma systems. Traditionally, trauma patients have been classified using the Injury Severity Score (ISS), but resource-based criteria have been proposed as an alternative. The aim of this study was to investigate the relationship between ISS and the use of life-saving interventions (LSI).

Methods: Retrospective cohort study using the Trauma Audit Research Network database for all adult patients (aged ≥18 years) between 2006 and 2014. Patients were categorised as needing an LSI if they received one or more interventions from a previously defined list determined by expert consensus.

Results: 193 290 patients met study inclusion criteria: 56.9% male, median age 60.0 years (IQR 41.2–78.8) and median ISS 9 (IQR 9–16). The most common mechanism of injury was falls <2 m (52.1%), followed by road traffic collisions (22.2%). 15.1% received one or more LSIs. The probability of a receiving an LSI increased with increasing ISS, but only a low to moderate correlation was evident (0.334, p<0.001). A clinically significant number of cases (5.3% and 7.6%) received an LSI despite having an ISS ≤8 or <15, respectively.

Conclusions: A clinically significant number of adult trauma patients requiring LSIs have an ISS below the traditional definition of major trauma. The traditional definition should be reconsidered and either lowered, or an alternative metric should be used.