It is unclear how the author inferred an increase from 3.4% to 12.1% in drivers who tested positive for cannabis only, from 2005 to 2014 [“Driving stoned: Marijuana legalization and drug-impaired driving [9],” BCMJ 2016;58:477-478]. According to the updated (2005–15) report from the Colorado Department of Transportation, it appears that the increase was actually from 3.4% in 2005 to 7.7% in 2014, much less than what is reported here. To the best of my knowledge, I am reading the same report that the author references in this commentary (www.codot.gov/safety/alcohol-and-impaired-driving/druggeddriving/drugged... [10]). Worth noting in this report, but not discussed in this commentary, is that this percentage had reached 8.9% in 2011 (before legalization took effect). I am concerned about this because the media reported extensively on this commentary, with a particular focus on the “tripling” of fatal car accidents among high drivers in Colorado postlegalization.
—Stephanie Lake, MSc
PhD student, UBC School of Population and Public Health, Vancouver