Association between drink driving and severity of crash injuries to road users

Objective:To determine the association between alcohol impairment in drivers and risk of severe injury in other road users in Hong Kong. Method:The Road Casualty Injury Information System (RoCIS) was set up by linking a regional hospital injury registry to the police traffic injury database. Based on the year 2004 linked dataset, a specific model namely the External Casualty Model (ECM) was designed to measure the association between severe injury outcome of other (non-driver) road user casualties (as stratified by ISS groups [ISS <9 or ISS ≥9]) and the level of alcohol impairment (as measured by breath alcohol concentration [BAC <22 μg/100 ml or BAC ≥22 μg/100 ml]) in drivers involving in the crash, controlling for the driver's demographics (age and sex) and behaviour (as measured by driving-offence points [DOP]) and another attribute (day of week of crash). Binary logistic regression was used in the analysis. Results: Out of 1818 matched RoCIS cases in the year 2004, 439 ECM records were available for analysis. Alcohol impaired drivers led to a significantly higher risk of severe injury to other road users (OR=4.2, 95%CI=1.21, 14.36, p=0.02). Crashes on weekdays seemingly led to a lower severe injury risk (OR=0.57, p=0.08) than crashes on weekends. DOP of drivers did not predict a higher severe injury risk to other road users. Conclusions: Alcohol impairment on driver increases the risk of severe injury to other road users by four times. Road safety education campaign should stress on this adverse impact of drink driving on innocent people.