Quantifying morbidity attributable to traumatic injury using a population-based matched cohort in Australia
R Mitchell, C Cameron, R McClure
Objectives To quantify the 12-month hospitalised morbidity and mortality attributable to traumatic injury using a population-based matched cohort in Australia.
Setting New South Wales, Queensland and South Australia, Australia.
Participants Individuals ≥18 years who had an injury-related hospital admission in 2009 formed the injured cohort. 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.
Primary outcome measures Using linked emergency department presentation, hospital admission and mortality records from 1 January 2008 to 31 December 2010 for both the injured and non-injured cohorts, 12-month mortality and pre-index and post-index injury hospital service use was examined. Adjusted rate ratios and attributable risk were calculated.
Results There were 167 600 individuals injured in 2009 and admitted to hospital in New South Wales, South Australia or Queensland with a matched comparison. The injured cohort had 3 times higher proportion of having ≥1 comorbidity preinjury, higher preinjury hospital service use, and a higher 12-month mortality compared with a non-injured comparison group. The injured cohort had 2.20 (95% CI 2.12 to 2.28) times higher rate of hospital admissions in the 12 months post the index injury admission compared with the non-injured comparison cohort. Injury was a likely contributory factor in at least 55% of hospitalisations within 12 months of the index injury hospitalisation.
Conclusions Individuals who had an injury-related hospitalisation had higher mortality and are hospitalised at increased rates for many months postinjury. While comorbid conditions are significant, they do not account for the differences in outcomes. This study contributes to informing research efforts on better quantifying the attributable burden of hospitalised injury-related disability and mortality in Australia.