Drug driving: a secondary analysis of factors associated with driving under the influence of cannabis in Jamaica

Discussion

This study is the first of its kind in the Caribbean region and sheds light on the impact of DUIC on a national population. The findings reveal that a significant number of Jamaican drivers who use cannabis, operate a vehicle under its influence, with more than 10% conceding to this unsafe and risky practice. It is worth noting the occurrence is eight times greater than the reported mean prevalence of 1.32% (range 0.0%–5.99%) in general driving populations across 13 participant countries of The European Union’s Driving under the Influence of Drugs, Alcohol and Medicines project.8 The high proclivity towards its use among Jamaicans, no doubt as a result of social and cultural influence,46 47 represents a worrying proposition given that extensive research demonstrates that cannabis use while driving, or under its influence, may impair driving ability.55

The second key finding is that among past-month cannabis users, more than 2 in 5 (43.3%) drivers report driving a vehicle while under the influence of cannabis (DUIC). This represents a marked difference compared with similar respondents in a previous study who admitted to DUI of alcohol (18%).56 Indeed, in terms of exposure, DUIC was far more commonplace among the Jamaican driving population than DUI of alcohol. A plausible rationale is that the effects of DUIC have not received the same level of public awareness as DUI of alcohol. Moreover, current legislation provides minimal legal deterrence to DUIC, lacking an effective roadside drug driving testing strategy and comprising a fine of approximately US$65 that is unlikely to dissuade offender motorists.57

The third critical finding is that the more frequent cannabis users are more likely to report DUIC. This study denoted that approximately 9 out of 10 Jamaicans who were past-month cannabis users and reported DUIC admitted to being heavy users (use 20 days or more in a month). The compelling significance of this finding is that a number of studies highlight the increased odds of motor vehicle crashes associated with acute cannabis intoxication,31 32 58 mainly because the psychoactive effects may persist for a significant period of time.59

The fourth key finding demonstrated a significant association between risk perception and the risk of developing cannabis dependence among vehicle drivers. Expectedly, drivers with no to low-risk perceptions of smoking cannabis showed higher risks of cannabis dependence. However, a salient finding is that approximately 30% of drivers with moderate to high-risk perception of smoking cannabis, whether sometimes or often, were also associated with an increased risk of cannabis dependence. Indeed, it may be beneficial to address the misperception that smoking cannabis is not dangerous among drivers who perceive it as less risky. Additionally, directing drivers who have been convicted or suspended for this behaviour towards a remedial programme, similar to those mandated for drunk driving, could prove effective.60 However, the high prevalence of cannabis dependence among drivers who acknowledge smoking cannabis as being harmful further underscores the fact that DUIC is becoming more socially acceptable,61 normative62 and less perceived as a risky behaviour.21

Finally, this study also revealed several sociodemographic factors associated with DUIC. Regression analysis indicated that being a young adult, employed in a job operating machinery, of the male sex, and the head of the household were predictive of DUIC, whereas being married and having a tertiary-level education were protective factors. Interestingly, the risk factors accrued were similar to those observed for DUIA among Jamaican drivers demonstrated in previous research.56 As such, the opportunity for legislators to include DUIC as part of an overall national DUI interventional effort, allow for comprehensive and collaborative efforts that a siloed approach to policymaking is unlikely to foster. Accordingly, a further call to improve data collection protocols regarding DUI behaviours and increase sobriety checkpoints in Jamaica, represent replicable and cost-effective strategies that have found favour in other low-income and middle-income countries (LMICs).63

Cumulatively, the findings of this study have heightened concerns regarding DUIC among Jamaican drivers, particularly in light of the island’s increasing annual road fatality rate.64 The legislation regarding drug driving must comply with global benchmarks. International policy-makers have sought to model drug-driving laws on those that have proven effective for DUI of alcohol, inclusive of a strategy that encourages roadside drug testing. DUIC can be measured through observed impairment in a Standardised Field Sobriety Test65–67 or Drug Evaluation and Classification68 programme by a police officer or by using point‐of‐collection testing devices.69 These strict policies use a per se or zero-tolerance approach, meaning that if THC is detected at or above a specific concentration in a biological sample, the driver is considered to have committed a DUIC offence, regardless of their level of impairment. Several countries, including Norway and Denmark, alongside a number of states in the USA,69 70 have adopted per se limits ranging from 2 to 5 ng/mL THC on oral fluid and blood tests, where studies demonstrate the first indications of impairment may occur, while other nations such as Australia endorse the de-facto zero-tolerance approach.71 While some studies establish that a level of 3.7 ng/mL THC is equivalent to the legal blood alcohol concentration of 0.05 g/dL accepted in a number of countries,72 73 other studies in the USA suggest an absence of a dose-dependent relationship between THC level and driving impairment, especially among frequent users where tolerance may be a factor.40 74 Notably, the accumulated literature regarding the impact of roadside drug testing remains in its infancy, given that most countries would have recently embarked on legislative reform. Notwithstanding, a number of contemporary research have yielded promising results that endorse the importance of roadside testing as part of a DUIC deterrence initiative.75–77

Driving necessitates a higher level of mental and motor dexterity, making it an intrinsically complex undertaking.78 The misperception that DUIC is not risky and that cannabis use adjunctly improves driving skills21 23 is further highlighted by this study’s prevailing finding that a substantial number of drivers (between approximately 30% and 50%) demonstrated a no to low-risk perception of smoking cannabis. This notable risk tolerance or lack thereof may also represent a concern in the workplace, given that DUIC drivers were predominantly employed in machine-operated jobs. Notwithstanding, cannabis-impaired driving, certainly within the Jamaican context, is likely also influenced by recent decriminalisation and medicalisation44 policies as seen elsewhere that have adopted a similar stance,79 and undoubtedly enhanced by sociocultural acceptance,47 easy access48 and availability of higher potency products.80 Accordingly, a calculated national initiative should seek to review current cannabis policy, include more robust regulatory mechanisms and disseminate a public education programme on the risks associated with cannabis use and driving as part of an overall prevention and deterrence effort. Furthermore, the data gleaned may provide the groundwork for policy change in reducing DUIC behaviours per recommendations established in other territories that have similarly endorsed decriminalisation or legalisation.81–85

One of the study’s limitations was that DUI information was self-reported, which can be affected by recall bias. Moreover, the inclination of many of the survey participants to give ‘socially acceptable’ answers and not admit any illegal activities might also introduce a response bias. Notably, this research could not establish causal relationships due to the nature of the cross-sectional data. However, one of the study’s strengths is that the validated CAST enhanced the reliability of the findings given that it is frequently used worldwide in national population sample studies.52 Although the data analysed in this study were collected in 2016, the findings are of immense value for national policy, providing a foundation for further research to build on and vitally fill a knowledge gap, especially in LMICs where global research is scarce.