The 4Cs (crash history, family concerns, clinical condition, and cognitive functions): a screening tool for the evaluation of the at-risk driver.

Objectives: To evaluate the effectiveness of crash history, family concerns, clinical condition, and cognitive function (the 4Cs, an interview-based screening tool for health providers working with older drivers) in identifying at-risk older drivers.
Design: Retrospective cohort study.
Setting: Clinical driving evaluation program at a teaching hospital in the United States.
Participants: One hundred sixty patients who completed comprehensive driving evaluations between 2003 and 2009.
Measurements: Medical record information was used to identify component and total 4Cs scores. Other measurements included the Trail Making Test, the Mini-Mental State Examination, and brake reaction time. The outcome variable was performance on a 45-minute road test.
Results: Fifty participants passed the road test, 67 failed, and 43 demonstrated marginal driving skills. The relationship between 4Cs scores and road test outcome was statistically significant (P<.001). The domains most strongly associated with road test outcome were cognitive function (P<.001) and family concerns (P=.01). Scores of 9 or greater-on the 4Cs identified 84% of participants who were at risk for poor road test performance.
Conclusion: The 4Cs, an interview based screening tool, may be a useful marker to identify at-risk older drivers.