The Impact of Benzodiazepines on Safe Driving

Abstract

Objective. Benzodiazepines are prescribed to relieve anxiety and aid sleep. Studies demonstrate that benzodiazepines increase odds of crash involvement, but little evidence exists regarding their impact on crash responsibility. We examined the impact of benzodiazepines on crash responsibility by drug half-life and driver age, using a case-control design with drivers aged 20 and over involved in fatal crashes in the United States from 1993–2006.

Methods. Drivers (all with BAC = 0) were classified as having no benzodiazepines detected versus short, intermediate, or long half-life benzodiazepines. Cases were drivers with at least one potentially unsafe driving action (UDA) in relation to the crash (e.g., speeding), a proxy measure for crash responsibility; controls had no UDAs recorded. Odds ratios (ORs) of any UDA by benzodiazepines half-life exposure were calculated, with adjustment for age, sex, other medication usage, and prior driving record.

Results. Compared with drivers not using benzodiazepines, drivers taking intermediate or long half-life benzodiazepines demonstrated increased odds of an UDA from ages 25 (intermediate OR: 1.59; 95% CI = 1.08, 2.33; long OR: 1.68; 95% CI = 1.34, 2.12) to 55 (intermediate OR: 1.50; 95% CI = 1.09, 2.06; long OR: 1.33; 95% CI = 1.12, 1.57). Drivers taking short half-life benzodiazepines did not demonstrate increased odds compared to drivers not using benzodiazepines.

Conclusions. Given the potential impact of benzodiazepines on driver safety, further experimental research is needed to better understand the effect of benzodiazepines on crash responsibility.

Keywords:

• Benzodiazepines
• Driving
• Drug-Impaired Drivers
• Crash Responsibility
• Crash Fatality

ACKNOWLEDGMENTS

The authors thank Owen Marks for his assistance with data management and Christina Snow and Sophie Regalado of the St. Joseph's Care Group Libraries for assistance with literature retrieval. Michel Bédard is a Canada Research Chair in Aging and Health (www.chairs.gc.ca); he acknowledges the support of the Canada Research Chair Program. This work is partial fulfillment of S. Dubois' MPH thesis, Lakehead University, Canada.

Notes

∗Given some cases may have multiple benzodiazepines per half-life category, totals indicates total number of cases with one or more of the particular half-life category

∗Rounded percentages provided

∗∗Chi-square values are presented for all variables with the exception of age, where the F-statistic is presented

∗∗∗Sixteen cases did not have sex coded

∗The chi-square statistic is reported for each four (benzodiazepines absent, short present, intermediate present, long present) by two (unsafe driver action present, unsafe driver action absent) comparison

∗Age centered at 45 years

∗Wald statistics are significant at the p < .001 level

∗∗Wald statistics are significant at the p < .01 level

∗∗∗Wald statistics are significant at the p < .05 level

†Wald statistic s are equal to p = .08