Introduction Previous studies on the effect of prescription medications on MVCs are sparse, not readily applicable to real-world driving and/or subject to strong selection bias. This study examines whether the presence of prescription medication in drivers’ blood is associated with being responsible for MVC.
Methods This modified case–control study with responsibility analysis compares MVC responsibility rates among drivers with detectable levels of six classes of prescription medications (anticonvulsants, antidepressants, antihistamines, antipsychotics, benzodiazepines, opioids) versus those without. Data were collected between January 2010 and July 2016 from emergency departments in British Columbia, Canada. Collision responsibility was assessed using a validated and automated scoring of police collision reports. Multivariable logistic regression was used to determine OR of responsibility (analysed in 2018–2019).
Results Unadjusted regression models show a significant association between anticonvulsants (OR 1.92; 95% CI 1.20 to 3.09; p=0.007), antipsychotics (OR 5.00; 95% CI 1.16 to 21.63; p=0.03) and benzodiazepines (OR 2.99; 95% CI 1.56 to 5.75; p=0.001) with collision responsibility. Fully adjusted models show a significant association between benzodiazepines with collision responsibility (aOR 2.29; 95% CI 1.16 to 4.53; p=0.02) after controlling for driver characteristics, blood alcohol and Δ−9-tetrahydrocannabinol concentrations, and the presence of other prescription medications. Antidepressants, antihistamines and opioids exhibited no significant associations.
Conclusion There is a moderate increase in the risk of a responsible collision among drivers with detectable levels of benzodiazepines in blood. Physicians and pharmacists should consider collision risk when prescribing or dispensing benzodiazepines. Public education about benzodiazepine use and driving and change to traffic policy and enforcement measures are warranted.
- motor vehicle occupant
- case-control study
- public health
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Contributors MA and JRB were responsible for the design of the work and acquisition of the data. SE was responsible for analysis and MA and SE were responsible for interpretation of data. All authors were responsible for drafting and revising the work. All authors approve the final version.
Funding This research was supported by a grant from the Canadian Institutes of Health Research (CIHR MOP-111002). JRB is funded by a Health Professional Investigator award from the Michael Smith Institutes of Health Research (CI‐SCH‐02894(11‐1)).
Competing interests None declared.
Patient and public involvement Patients and/or the public were not involved in the design, or conduct, or reporting, or dissemination plans of this research.
Patient consent for publication Not required.
Ethics approval This study was approved by the University of British Columbia research ethics board (REB) and by the research ethics boards of the four health boards governing the seven trauma centres from which we collected data (Vancouver Coastal Health, Fraser Health, Interior Health and Vancouver Island Health Authorities).
Provenance and peer review Not commissioned; externally peer reviewed.
Data availability statement Data are available on reasonable request.
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