Driving tests with older patients: effect of unfamiliar versus familiar vehicle

The aim of the study was to study the effect, for older license holders, of taking a driving test with an unfamiliar vehicle, as compared to their own cars. The study population consisted of licensed patients 65–85 years referred to the Traffic Medicine Centre (TrMC), Huddinge University Hospital, for an evaluation of their medical and cognitive fitness to drive. In the clinical practice of TrMC, driving tests have been used since 1997, with inspectors from the Swedish National Road Administration (SNRA) acting as evaluators. Initially, patients were allowed to use their own cars. From the beginning of the year 2000, however, dual brakes were made mandatory and most evaluations were then made with SNRA cars. When comparing the outcomes of driving tests from the period prior to 2000 (n=96) and after 2000 (n=69), it was found that the number of drivers who failed the test increased by 16%. Also, those who passed the test after more than one trial decreased by 20%. The potential of the neuropsychological assessment to correctly classify drivers in outcome groups was considerably reduced in the period after 2000. These results support the view that, for older drivers with cognitive deterioration, the need to adapt to an unfamiliar vehicle represents a supplementary cognitive load that may compromise their driving ability and the validity of the assessment. A measure aimed only at increasing the safety of examiners and examinees thus had an unintended side-effect that is detrimental to older clinical populations.