Objectives: to evaluate the informative capability of merging data from police and medical data-sets in the assessment of adverse health effects and costs for the health system of road traffic accidents in an urban area (Florence City).
Design: record linkage between the road traffic accidents data-base of Municipal Police and routinely collected medical data (emergency department access and hospital admission data-bases). Municipal Police data-base collects information (i.e: dynamics and localization of road traffic accident, emergency department or hospital of access, etc.) about road traffic accidents casualties occurred in Florence City (completeness: about 97% of events).
Setting: Florence City, year 2002.
Results: information about emergency department access or hospital admission were found for 74.8% (4,001/5,350) of people classified as "injured" in the Municipal Police data-base: 72.8% (3,895 subjects) treated in an emergency department and 12.3% (656 subjects) hospitalised. Among patients with medical information, 81.9% was treated in emergency departments for less severe injuries, 1.8% had a fracture treated in the emergency department and 16.3% was hospitalised. Fractures (42.7% of all hospitalisations) and head injuries (33.5%) were the most frequent discharge diagnoses. On the basis of diagnosis and of the length of hospital stay, we estimate that about 1% road traffic accidents casualties (fatalities not included) had very severe outcome or disability. The cost for the health system of treatment of people injured in road traffic accidents can be estimated at about 2.2 millions of euros (1.3% of total hospitalisations cost per year for residents in Florence). The characteristics of medical data-sets suggest an underestimation of the actual number of emergency department accesses. It is unlikely that this underestimation notably affects the results for the low severity of the majority of emergency departments accesses.
Conclusions: record linkage between Municipal Police and routinely collected medical data-sets is an useful method to assess health adverse effects and costs for health system of road traffic accidents, allowing to analyse the characteristics of casualties by type of road user. Besides, at a local level, the method allows to identify the more dangerous roads taking into account also the severity of injuries.