The effects of cannabis intoxication on motor vehicle collision revisited and revised

Abstract

Acute cannabis intoxication is associated with a statistically significant increase in motor vehicle crash risk. The increase is of low to medium magnitude. Remaining selection effects in the studies used may limit causal interpretation of the pooled estimates.

Response to Li et al . (2017): Cannabis use and crash risk in drivers

“…In a recent meta-review on the associations between cannabis use and traffic crash risks [1], we also replicated two earlier meta-analyses [2,3] and argued that these presented pooled risk estimates with substantial upwards bias. A response from Li et al [4], the authors of one of these earlier meta-analyses, argues that our criticism was unfounded on three issues.…”

“…The authors respond that they defined search terms explicitly, followed PRISMA and MOOSE guidelines, and made a 'detailed and 11-level graph' illustrating the process. This misses our point: as we wrote, their 'pooled studies report qualitatively different types of associations' [1], making it unclear what the resulting pooled estimate is supposed to be a pooled estimate of. To illustrate: imagine that ever-users of cannabis on average are impaired 10% of the time they spend driving, and that cannabis doubles your crash risk while impaired.…”

Cannabis use and crash risk in drivers

“…In a recent paper published in Addiction, Rogeberg & Elvik [1] replicated and criticized two meta-analyses synthesizing the epidemiological evidence for marijuana use and crash risk in drivers [2,3]. The two meta-analyses were performed independently by two research teams (ours at Columbia University and Asbridge et al's [3] at Dalhousie University) and were published a few months apart in 2012 in two highly regarded academic journals.…”

The sources of behavioral reinforcement : an examination of nonsocial reinforcement theory.

“…A positive correlation has been found between marijuana use and risk of driving while under the influence, indicating that individuals who use marijuana more often are more likely to also drive while under the influence (Rogeberg & Elvik, 2016). Impairments in learning and issues with forgetting information have been identified in chronic marijuana smokers (Grant et al, 2003).…”

“…Immediate physiological impacts from marijuana use include impaired driving while under the influence (Rogeberg & Elvik, 2016) and impairments in learning and memory (Grant, Gonzalez, Carey, Natarajan, & Wolfson, 2003). Long term use can lead to increased risk of lung cancer and other health risks (Imtiaz et al, 2016).…”