Burden of road traffic injuries: Disability-adjusted life years in relation to hospitalization and the maximum abbreviated injury scale

Abstract

Background: The consequences of non-fatal road traffic injuries (RTI) are increasingly adopted by policy makers as an indicator of traffic safety. However, it is not agreed upon which level of severity should be used as cut-off point for assessing road safety performance. Internationally, within road safety, injury severity is assessed by means of the maximum abbreviated injury scale (MAIS). The choice for a severity cut-off point highly influences the measured disease burden of RTI. This paper assesses the burden of RTI in terms of disability adjusted life years (DALYs) by hospitalization status and MAIS cut-off point in the Netherlands.

Methods: Hospital discharge register (HDR) and emergency department (ED) data for RTI in the Netherlands were selected for the years 2007-2009, as well as mortality data. The incidence, years lived with disability (YLD), years of life lost (YLL) owing to premature death, and DALYs were calculated. YLD for admitted patients was subdivided by MAIS severity levels.

Results: RTI resulted in 48,500 YLD and 27,900 YLL respectively, amounting to 76,400 DALYs per year in the Netherlands. The largest proportion of DALYs is related to fatalities (37%), followed by admitted MAIS 2 injuries (25%), ED treated injuries (16%) and admitted MAIS 3+ injuries (18%). Admitted MAIS 1 injuries only account for a small fraction of DALYs (4%). In the Netherlands, the diseases burden of RTI is highest among cyclists with 39% of total DALYs. One half of all bicycle related DALYs are attributable to admitted MAIS 2+ injuries, but ED treated injuries also account for a large proportion of DALYs in this group (28%). Car occupants are responsible for 26% of all DALYs, primarily caused by fatalities (66%), followed by admitted MAIS 2+ injuries (25%). ED treated injuries only account for 5% of DALYs in this group.

Conclusions: When using admitted MAIS 3+ or admitted MAIS 2+ as severity cut-off point, 54% and 80% of all DALYs are captured respectively. Assessing the influence of different severity cut-off points by MAIS on the proportion and number of DALYs captured gives valuable information for guiding choices on the definition of serious RTI.

Keywords: Disability adjusted life years (DALY); Disease burden; Injury severity; Maximum abbreviated injury scale (MAIS); Road traffic injury (RTI).