Clinical Utility of the Trail-Making Test as a Predictor of Driving Performance in Older Adults

Objectives: To assess the clinical utility of the Trail-Making Tests (TMTs) as screens for impaired road-test performance.

Design: Secondary analyses of three data sets from previously published studies of impaired driving in older adults using comparable road test designs and outcome measures.

Setting: Two academic driving specialty clinics.

Participants: Older drivers (N = 392; 303 with cognitive impairment, 89 controls) from Rhode Island and Missouri.

Measurements: Standard operating characteristics were evaluated for the TMT Part A (TMT-A) and Part B (TMT-B), as well as optimal upper and lower test cut-points that could be useful in defining groups of drivers with indeterminate likelihood of impaired driving who would most benefit from further screening or on-road testing.

Results: Discrimination remained high (>70%) when cut-points for the TMTs derived from Rhode Island data were applied to Missouri data, but calibration was poor (all P < .01). TMT-A provided the best utility for determining a range of scores (68-90 seconds) for which additional road testing would be indicated in general practice settings. A high frequency of cognitively impaired participants unable to perform the TMT-B test within the allotted time limited the utility of the test (>25%). Mere inability to complete the test in a reasonable time frame (e.g., TMT-A > 48 seconds or TMT-B > 108 seconds) may still be a useful tool in separating unsafe from safe or marginal drivers in such samples.

Conclusion: The TMTs (particularly TMT-A) may be useful as screens for driving impairment in older drivers in general practice settings, where most people are still safe drivers, but more-precise screening measures need to be analyzed critically in a variety of clinical settings for testing cognitively impaired older drivers.