Recalculation of Survival Risk Ratios

Project: Research

Project Description

Work recently undertaken by the Monash University Accident Research Centre (MUARC) for the Centre for Road Safety (CRS) provided advice on the various measures of injury severity that can be derived from the linked datasets analysed by CRS (D'Elia & Newstead, 2016). In the context of injuries sustained in road crashes, threat to life measures provide a measure of the probability that a patient will die from the injuries sustained; they are used to define and categorise injury severity above hospitalisation. It was recommended by MUARC that the data-derived International Classification of Diseases (ICD) Injury Severity Score (ICISS) should be used as the threat to life measure of serious injury rather than the consensus-derived Abbreviated Injury Scale (AIS). ICISS involves calculating a Survival Risk Ratio (SRR) for each ICD injury code and has been shown to accurately predict mortality and be clinically relevant (Osler, Rutledge, Deis, & Bedrick, 1996).

Currently, the SRRs used by CRS are calculated using hospital separation records relating to land-transport crashes (road traffic and non-traffic crashes) only (Bambach, Mitchell, Grzebieta, & Williamson, 2012). However, it can be assumed that the survivability of an injury is the same whether the injury was sustained in a land transport accident or otherwise. Hence, the recommendation by D’Elia and Newstead (2016) that SRRs be recalculated using all NSW morbidity data linked to mortality data. This approach addresses some of the known limitations of using SRRs as using a complete set of hospital morbidity data linked to mortality data captures the full range of injury as well as deaths that occur outside of hospital. Thus more accurate estimates are produced of survivability by specific injury independent of cause. Applying a single set of SRRs to a selected period of data also means that injury severity trends reflect road safety trends rather than health care system performance changes (D'Elia & Newstead, 2016).
Effective start/end date1/03/1928/02/20


  • Survival Risk Ratios
  • public policy
  • injury severity
  • threat to life
  • Injury Severity Score
  • linked data