Age-based medical screening of drivers in Switzerland: an ecological study comparing accident rates with Austria and Germany.

BACKGROUND: In Switzerland, as in various other countries throughout the world, elderly drivers have to pass a medical screening assessment every two years to keep their driver's licence. The scientific literature shows no clear evidence that these policies improve road safety. This study evaluated the effects of the Swiss screening policy by comparing the accident and injury rates of elderly road users in Switzerland with those in Austria and Germany, two neighbouring countries without systematic age-based screening policies. The aims of this study were to examine if the screening policy is associated with a reduced risk of elderly car drivers causing serious accidents (research question 1) or with an increased risk of elderly pedestrians or (e-)cyclists being seriously or fatally injured (research question 2).

METHODS: In all three countries, data on accidents were taken from official statistics based on police reports and mileage data from national mobility surveys. An accident was defined as serious if at least one person is seriously or fatally injured in it. Accident and injury rates were calculated using distances driven and population size as measurement of exposure. Multiple Poisson regression models were used to examine the association between the Swiss policy and the accident or injury risk of elderly persons.

RESULTS: We found no association between the screening policy for elderly drivers in Switzerland and their risk of causing a serious accident (incidence rate ratio [IRR] 1.24, 95% confidence interval [CI] 0.79-1.94). Contrary to other studies, however, the Swiss policy was not associated with an increased risk of elderly pedestrians (IRR 1.16, 95% CI 0.80-1.68) and (e-)cyclists (IRR 0.79, 95% CI 0.56-1.12) being seriously or fatally injured.

CONCLUSIONS: The intended positive effect of the Swiss screening policy on accident rates of elderly drivers could not be demonstrated in this study. These findings serve as a basis for discussion on how to proceed with the policy in the future.