[Skip to Navigation]
Comment & Response
February 4, 2019

Association Between April 20 Cannabis Celebration and Fatal Crashes

Author Affiliations
  • 1Department of Medicine, University of British Columbia, Vancouver, British Columbia, Canada
  • 2Centre for Clinical Epidemiology and Evaluation, Vancouver, British Columbia, Canada
  • 3Centre for Health Evaluation and Outcome Sciences, Vancouver, British Columbia, Canada
  • 4Department of Medicine, University of Toronto, Toronto, Ontario, Canada
  • 5Institute for Clinical Evaluative Sciences, Toronto, Ontario, Canada
JAMA Intern Med. 2019;179(3):456. doi:10.1001/jamainternmed.2018.8094

To the Editor In our Research Letter1 examining crash risks on the “4/20” counterculture holiday, we identified drivers (rather than crashes) as the unit of analysis because one or more drivers may contribute to a crash. This approach also helps optimize interpretability for clinicians and policymakers around driving risks despite breaching strict assumptions for statistical independence. Furthermore, as Aydelotte and colleagues2 point out, similar results were obtained whether the driver (OR, 1.12; 95% CI, 1.05-1.19) or the crash (incidence rate ratio, 1.10; 95% CI, 1.02-1.20) was the unit of analysis. The observed difference in calculated absolute risks simply indicates the average crash involves more than one driver.

Limit 200 characters
Limit 25 characters
Conflicts of Interest Disclosure

Identify all potential conflicts of interest that might be relevant to your comment.

Conflicts of interest comprise financial interests, activities, and relationships within the past 3 years including but not limited to employment, affiliation, grants or funding, consultancies, honoraria or payment, speaker's bureaus, stock ownership or options, expert testimony, royalties, donation of medical equipment, or patents planned, pending, or issued.

Err on the side of full disclosure.

If you have no conflicts of interest, check "No potential conflicts of interest" in the box below. The information will be posted with your response.

Not all submitted comments are published. Please see our commenting policy for details.

Limit 140 characters
Limit 3600 characters or approximately 600 words