Although screening policies for older drivers based on chronological age are widely used in many countries, previous research has shown that increasing age does not cause higher crash rates and that consequently, chronological age per se is at best only a weak predictor of safe driving performance. Previous research on age-based mandatory screening of older drivers has not been able to demonstrate any safety benefits from screening measures. The present study is a population-based evaluation of the safety effects that the introduction of the cognitive test as an age-based screening tool has had in Denmark. The primary data used came from the Danish road accident register. The present study compared the number of fatal accidents before and after the implementation of screening for cognitive impairment. There were two main findings. First, there was no statistically significant difference in the number of older drivers involved in fatal accidents before and after the implementation of the screening process, indicating that the screening had no effect on the safety of older drivers. Second, there was a significant increase in the number of unprotected older (but not younger) road users who were killed between the two periods of observation, suggesting that the screening process produced a modal shift among older persons from driving to unprotected, significantly less safe modes of transportation. As a consequence, the number of fatalities in this group increased. Older driver screening is an example of a political measure that intuitively makes sense, but fails to produce the desired benefits. On the contrary, on a system level, it decreases the overall safety and is connected to various direct and indirect costs.
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