An evaluation of road crash injury severity using diagnosis based injury scaling

In Western Australia, information in Police crash reports currently provides the only measure of injury severity following a road crash. These severity ratings are determined by the attending Police Officer as [1] fatal; [2] hospitalised; [3] minor injury; or [4] non-medical.
This paper makes use of ICD-Based Injury Severity Score (ICISS) methodology to determine the severity of road crash injuries using linked hospital and death records. The severity of an injury is determined by calculating threat to life ratios for patients admitted to Western Australian hospitals from 1988 to 2006.
Certain road user groups appear to be grossly under-reported by Police as requiring hospitalisation, when compared to hospital records. Crashes involving a motorcyclist, pedestrian or bicyclist all appear to have higher numbers of hospital admissions than those reported to Police. Conversely, road crash casualties involving a motor vehicle appear to be over represented by police, indicating that not all crashes classified as requiring hospitalisation by the attending Police Officer actually end up being admitted to hospital.
According to hospital admission records, motor vehicle occupants make up the largest portion of road crash hospital admissions, contributing to approximately 54% of all road crash hospital admissions. Motorcyclists are the second biggest contributor, with 18% of hospital admissions. Pedestrians and other road users each make up 10% of hospital admissions and finally bicyclists contribute to 7%.
Pre-defined severity of injury thresholds were used to determine the seriousness of an injury using hospital admission records. Analysis indicates that serious injuries contribute to approximately 26% of Western Australian hospital admissions by road crash casualties and are growing at a faster rate than non- serious injuries.
This paper reports trends in hospital admissions and injury severity for road crash casualties over the period 1988 – 2006. The severity of an injury is determined using hospital discharge summary information. Comparisons are made with numbers of road crashes reportadmissions, making use of linked hospital and death records for the period.