Usability of Norm Values on Results from a Simulator Device and Cognitive Tests in Traffic Medicine

Abstract

Introduction Driving is an essential everyday task for most adults, and fitness to continue car-driving after a brain injury/disease is a common issue in rehabilitation settings. There is no consensus on how this assessment should be performed and thus further research and development are of great value. The aim was to study the usability of cut-off values, based on recently developed norm values for a driving simulator device (CyberSiM), as well as cognitive tests, for patients already considered fit-to-drive after a standardized traffic medical investigation. Methods The study had a retrospective case-control design. Norm results (n = 129) were compared with patient results (n = 126) divided into two age groups (≤59 years and ≥60 years). Results from Useful Field of View, Trail Making Test, Nordic Stroke Driver Screening Assessment as well as a simulator device (CyberSiM) were compared. Results The group of patients considered fit-to-drive after a traffic medicine assessment had worse results on all cognitive tests compared with norms. Results on CyberSiM subtests II and III did not differ from norms. The proportion of patients within suggested cut-off limits (mean±2SD norm) and considered fit to drive (mean±2SD norm) were highest (75–95%) for all three subtests of CyberSiM and for Useful Field of View in both age groups. Conclusion Availability of norm values in decision on continued driving is of value when interpreting the results of cognitive assessments sensitive to age, but it must be handled with care because many factors are important for individuals’ ability to drive.