OBJECTIVE: The purpose of the study was to determine whether a new method of scoring the Clock Drawing Test (CDT) is a reliable and
valid method for identifying older adults with declining driving competence.
DESIGN: Prospective cohort study.
SETTING: An outpatient driving evaluation clinic.
PARTICIPANTS: One hundred nineteen community-dwelling, active drivers with a valid driver’s license, aged 60 and older referred for driving
evaluation.
MAIN OUTCOME MEASURES: The CDT and a driving test using a STISIM Drive simulator.
RESULTS: The CDT showed a high level of accuracy in predicting driving simulation outcome (area under the receiver-operator curve,
0.90; 95% confidence interval, 0.82 to 0.95). CDT scoring scales were comparable and all correlations between CDT scores and
driving performance were negative, implying that as the CDT score decreases, the number of errors increases. Interrater reliability
of CDT scores was 0.95. Subjects scoring less than 5 out of 7 points on the CDT made significantly more driving errors, hazardous
and in total (P<.001).
CONCLUSIONS: The CDT can help establish problems with executive function and indicate the need for a formal driving evaluation. Our CDT
scoring scale is a reliable, valid, and time-effective screening tool for identifying elderly drivers in need of further evaluation.
Key words clock drawing - driver screening - elderly drivers - fitness to drive
The authors have no conflicts of interest to report. An earlier version of this article was presented at the 2002 American
Geriatrics Society meeting, Washington, DC.
This research was supported in part by The Virginia Center on Aging, Alzheimer’s and Related Diseases Research Award Fund.