The Utah Driver License Division has implemented a program since 1979 that restricts drivers with medical conditions by functional ability category (medical condition) according to their functional ability level. This study compares the citation, all crash, and at-fault crash rates per eligible licensed days of restricted and unrestricted drivers with medical conditions 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 multiple 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 restriction classification at the time of occurrence. Corresponding relative risks and confidence intervals were calculated. Overall, for most functional ability categories, unrestricted drivers with medical conditions as identified through the existing program had higher crash and at-fault crash rates compared to their corresponding comparison groups. For unrestricted drivers, the highest risk of at-fault crash was found in the learning, memory and communications category where the risk of at-fault crash was 3.63 times higher than their respective comparison group (95% CI 2.00, 6.60). The greatest differences in at-fault crash rates were found in several restricted license categories. Restricted drivers in the musculoskeletal abnormality or chronic medical disability group had a rate 11.29 times higher than their comparison drivers (95% CI 2.39, 53.25). Restricted drivers in the alcohol and other drugs category had an at-fault crash rate that was 5.75 times higher than their respective comparison group (95% CI 2.26, 14.61). Further evaluation of the crash and citation rates at specific functional ability levels, and crash environments by category, may provide indications for changing the levels at which restrictions are applied, or provide indications for new or additional types of restrictions to reduce crashes and citations in these populations.


  • English

Media Info

  • Features: Appendices; Figures; References; Tables;
  • Pagination: 114 p.

Subject/Index Terms

Filing Info

  • Accession Number: 00794718
  • Record Type: Publication
  • Report/Paper Numbers: HS-809 023,, NHTSA Technical Report
  • Contract Numbers: DTNH22-96-H-59017
  • Files: HSL, NTL, TRIS, USDOT
  • Created Date: Jun 16 2001 12:00AM