Citation

Asbridge M, Mann R, Cusimano MD, Tallon JM, Pauley C, Rehm J. Prev. Med. 2014; 66: 80-86.

Affiliation

Department of Social and Epidemiological Research, Centre for Addiction and Mental Health, 33 Russell Street, Toronto, Ontario, Canada, M5S 2S1; Dalla Lana School of Public Health, University of Toronto, 155 College Street, Toronto, Ontario, Canada, M5T 3M7; Epidemiologic Research Unit, Clinical Psychology and Psychotherapy, Dresden University of Technology, Mommsenstraße 9, 01069, Dresden, Germany.

Copyright

(Copyright © 2014, Elsevier Publishing)

DOI

10.1016/j.ypmed.2014.06.006

PMID

24945694

Abstract

OBJECTIVE: To examine whether alcohol and cannabis consumption increase crash risk among non-fatally injured bicyclists (N=393) seen in three Canadian emergency departments, between April 2009 and July 2011.

METHOD: Employing a case-crossover design, cannabis and alcohol were identified through blood sample or by self-report. All cyclists were involved in a crash and exposure status (cannabis and alcohol) was compared between case period (current crash) and two control periods: prior to the last time the victim cycled around the same time of day; and the typical use prior to bicycling. Crash risk was assessed through conditional fixed effects logistic regression models.

RESULTS: Approximately 15% of cyclists reported using cannabis just prior to the crash, and 14.5% reported using alcohol. Cannabis use identified by blood testing or self-report in the case period and by self-report in the control period yielded a crash risk of 2.38 (1.04-5.43); however, when self-report was used for both the case and control periods the estimate was 0.40 (0.12-1.27). Alcohol use, as measure either in blood or self-report, was associated with an odds ratio of 4.00 (95% CI: 1.64- 9.78); results were similar when alcohol was measured by self-report only.

CONCLUSION: Cannabis and alcohol use each appear to increase the risk of a non-fatal injury-related crash among bicyclists, and point to the need for improved efforts to deter substance use prior to cycling, with the help of regulation, increased education, and greater public awareness. However, cannabis results should be interpreted with caution, as the observed association with crash risk was contingent on how consumption was measured.

Keywords: Cannabis impaired driving; DUID; Ethanol impaired driving

Language: en