Direct and indirect effects of marijuana use on the risk of fatal 2-vehicle crash initiation

Abstract

Background Marijuana and alcohol each play a significant role in fatal crash initiation. We decomposed the total effect of marijuana use in the presence or absence of alcohol on fatal crash initiation into direct and indirect effects. Methods Pair-matched data on 5856 culpable drivers (initiators) and 5856 nonculpable drivers (noninitiators) involved in the same fatal 2-vehicle crashes recorded in the Fatality Analysis Reporting System between 2011 and 2016 were analyzed using the conditional logistic regression model and the unified mediation and interaction analysis framework. Results Crash initiators were more likely than noninitiators to test positive for marijuana (16.1% vs. 9.2%, P < 0.001), alcohol (28.6% vs. 9.7%, P < 0.001) and both substances (6.3% vs. 1.6%, P < .0001). Adjusted odds ratios of fatal 2-vehicle crash initiation revealed a positive interaction on the additive scale between marijuana and alcohol. Of the total effect of marijuana use on fatal 2-vehicle crash initiation, 68.8% was attributable to the direct effect (51.5% to controlled direct effect and 17.3% to reference interaction effect with alcohol) and 31.2% to the indirect effect (7.8% to mediated interaction effect and 23.4% to pure indirect effect through alcohol). Conclusion Our results indicate that the increased odds of fatal 2-vehicle crash initiation associated with marijuana use is due mainly to the direct effect.

Use of Labor Neuraxial Analgesia for Vaginal Delivery and Severe Maternal Morbidity

“…Statistical analysis was performed with R version 3.6.2 (The R Foundation) and specific packages ( mice for multiple imputations, Matching for matching, and survival for conditional logistic regression). Mediation analysis was performed using SAS version 9.4 (SAS Institute) …”

Risk of Motor Vehicle Collisions and Culpability among Older Drivers Using Cannabis: A Meta-Analysis

“…During the data extraction process, 11 additional studies were excluded due to MVC or culpability data being unavailable for older adults. Data extraction was completed for seven studies [ 29 , 31 , 32 , 33 , 34 , 35 , 36 ], all of which were observational in design. Reference list scanning did not result in the inclusion of additional studies.…”

“…Data request letters were sent to corresponding authors of studies that did not report findings specific to older adults. Four of 47 authors replied with the relevant data: Jørgenrud et al [ 32 ], Brubacher et al [ 34 ], Poulsen et al [ 35 ], and Chihuri and Li [ 36 ] all provided usable data specific to adults aged 50 and older.…”

Can cannabis kill? Characteristics of deaths following cannabis use in England (1998–2020)

“…Cannabis is thought to be highly susceptible to PMR due to its lipophilic nature and high volume of distribution (4–14 L/kg) (Yarema and Becker, 2005). In addition to the evident risk of fatal injury that this poses to the driver, potential for harm extends to passengers and others in the local vicinity (Chihuri and Li, 2020; Li et al., 2012; Martin et al., 2017). Guidance regarding the timeframe at which it can be deemed ‘safe’ to drive following cannabis use is, however, difficult to define due to variations in dose, dosage form, route of administration, interindividual metabolism and excretion (McCartney et al., 2021).…”