Predictors of driving outcomes including both crash involvement and driving cessation in a prospective study of Japanese older drivers.

The first aim of this study was to investigate predictors of future traffic crash involvement, taking into account bias in the handling of data for former drivers. The second aim was to compare characteristics of former drivers and crash-involved drivers in order to gain an understanding of appropriate driving cessation among older drivers. In all, 154 drivers aged 70 years or older participated in the baseline interview and the follow-up survey conducted two years later. In the baseline interview, participants were asked to respond to a questionnaire, take the Useful Field of View test® (UFOV), and complete the Mini-Mental State Examination. In the follow-up survey, participants were asked by mail or telephone whether they had stopped driving. Participants reporting that they still drove were invited to participate in a subsequent interview. Based on the information obtained in the follow-up survey, participants were classified as follows: driving cessation group (n=26); crash-involved group (n=18); and crash-free group (n=110). A multinomial logistic regression was then used to analyse the data. Contrary to the results of previous studies, we found older age to be associated with crash involvement but not with driving cessation. The cessation group had more decreased cognitive processing speed than the crash-involved and crash-free groups. Crash history was also predictive of crash involvement. Participants who were subject to license renewal between baseline and follow-up had a greater tendency to continue driving. Results suggested that age and crash history could potentially identify high-risk older drivers. The predictive power of cognitive processing speed is reduced under certain conditions. License-renewal procedures may induce Japanese older adults to continue driving. Future studies should use a large national sample to confirm the results of the present study.