Quantifying morbidity attributable to traumatic injury using a population-based matched cohort in Australia

ABSTRACT Objective This study aims to quantify 12-month morbidity attributable to traumatic injury using a population-based matched cohort in Australia. Approach A population-based matched cohort study of individuals ≥18 years using linked emergency department (ED) presentation, hospital separation and mortality records from three Australian states during 1 January 2008 to 31 December 2010. Injury admissions were identified using a principal diagnosis of injury (ICD-10-AM: S00-T75 or T79). The first injury-related hospital admission during 2009 was identified as the index injury admission and pre and post-index injury health service use was examined. The non-injured comparison cohort was randomly selected from the electoral roll and was matched 1:1 on age, gender, and postcode of residence at the date of the index injury admission of their matched counterpart. Comorbidities were identified using diagnosis classifications and a 1-year lookback period. Injury severity was estimated using the International Classification of Injury Severity Score (ICISS): minor (≥0.99), moderate (0.942-<0.99) and serious (<0.942). Negative binomial and Poisson regression methods will be used to quantify associations between injury and counts of hospital admissions 12-month post-index injury health service use. Results There were 166,032 individuals injured in 2009 and admitted to hospital in New South Wales, South Australia or Queensland with a matched comparison. Males represented 57% of those injured, 30.1% were aged 18-34 years, 37.9% were aged 35-64 years, 32.1% were aged ≥65 years and 65.1% resided in an urban location. Comorbidities were more common in the injured cohort (χ² =9384.5, df (2), p