The impact of benzodiazepines on safe driving

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.

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.

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.

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