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Technical Report Documentation Page

1. Report No.

DOT HS 809 211

2. Government Accession No.
3. Recipient's Catalog No.
4. Title and Subtitle

Further Analysis of Drivers Licensed with Medical Conditions in Utah

5. Report Date
March 2001
6. Performing Organization Code 
7. Author(s)

D. D. Vernon, E. Diller, L. Cook, J. Reading, and J. M. Dean

8. Performing Organization Report No.
9. Performing Organization Name and Address

410 Chipeta Way, Suite 222
Salt Lake City, UT 84108

10. Work Unit No.
11. Contract or Grant No.
DTNH22-96-H-59017 Modification 0004
12. Sponsoring Agency Name and Address

National Highway Traffic Safety Administration
U.S. Department of Transportation
400 7th Street, S.W.
Washington, DC 20590

13. Type of Report and Period Covered
NHTSA Technical Report
1992 – 1996
14. Sponsoring Agency Code
15. Supplementary Notes
16. Abstract

The Utah Driver License Division has implemented a program since 1979 that restricts drivers with medical conditions by functional ability category (medical condition) by assigning them a functional ability level. This study compares the citation, all crash, and at-fault crash rates (per eligible licensed days) of medical conditions drivers at each functional ability level, by category, to the rates of comparison drivers matched on age group, gender and county of residence over a five year period. Analyses were performed separately for drivers reporting single medical conditions and those reporting 2 or more medical conditions. Probabilistic linkage was used to link data from different databases in order to determine the crash, at fault crash and citation rates by functional ability level classification at the time of occurrence. Corresponding relative risks and confidence intervals were calculated.

Overall, for most functional ability categories, drivers in the medical conditions program had higher crash and at-fault crash rates compared to their corresponding comparison groups, occurring at the numerically lowest (least restricted) functional ability levels. The relative risk (odds ratios) were generally fairly modest, in the 1.5-2.5 range. For drivers with multiple medical conditions, the functional ability levels were collapsed into two groups, unrestricted and restricted driving privileges. Of the combinations of medical conditions analyzed, roughly half had higher risk of crashes and at fault-crashes than comparison drivers; unrestricted and restricted drivers did not appear to differ materially. Further evaluation of the medical conditions program, taking into account true exposure rates (miles driven), may be warranted.

17. Key Words

functional motor ability, medical conditions, drivers, crash, citation, diabetes, epilepsy, cardiovascular, pulmonary, alcohol, vision, elderly, probabilistic linkage, CODES

18. Distribution Statement

This document is available to the public from the National Technical Information Service,
Springfield, VA 22161

19. Security Classif. (of this report)
20. Security Classif. (of this page)
21. No. of Pages
22. Price

Form DOT F 1700.7 (8-72) Reproduction of completed page authorized

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