DRIVER LICENSES AS A MEASURE OF OLDER DRIVERS EXPOSURE - A METHODOLOGICAL NOTE

The limitations of the number of driver licenses as an estimate of dri ving exposure were demonstrated by comparing Finnish and Swedish drive r licensing practices, licensing rates and accident rates of older dri vers. In Sweden, there is no screening for older license holders, and most of them keep their licenses for life. In Finland, there is a heav y and costly medico-legal control system for older license holders, le ading to both screening and self-screening. Consequently, in the two c ountries, the numbers of driver licenses do not reflect the numbers of active older drivers in the same manner. This difference affects the comparative accident statistics: with respect to population, Finland a nd Sweden have similar age trends in accidents risk, but with respect to the number of driver licenses, the Finnish older drivers seem to ha ve a higher risk of accident than the Swedish ones. It is concluded th at if group comparisons of accident risk are presented using the numbe r of driver licenses as an estimate of exposure, the licensing legisla tion and practice should affect all the groups in an identical manner for the comparison to be valid.