Electronic Thesis and Dissertation Repository

Thesis Format

Integrated Article

Degree

Doctor of Philosophy

Program

Health and Rehabilitation Sciences

Supervisor

Alvarez, Liliana

Abstract

Young drivers in Canada report the highest rates of cannabis use and impaired driving while expressing the least concern toward driving under the influence of cannabis (DUIC). Since cannabis increases crash risk, preventing youth from DUIC remains a top public health priority. This dissertation aimed to apply the six-step Intervention Mapping framework to develop, implement, and evaluate a brief smartphone intervention called High Alert, designed to reduce DUIC among high-risk youth in Ontario. In Study 1, the first four steps of Intervention Mapping were applied to systematically develop High Alert while integrating evidence, theory, and user feedback. This process involved conducting a needs assessment (Step 1), identifying intervention objectives (Step 2), selecting theory-based methods and practical strategies (Step 3), and creating intervention components and materials (Step 4). The program was pre-tested with five youth and five adult cannabis educators, and their feedback informed refinements before pilot testing. Study 2 applied Step 5 to pilot test High Alert’s implementation and preliminary efficacy through a three-arm pilot randomized controlled trial involving 102 Ontario youth with recent DUIC (≥3 instances in the past 3 months). Findings reveal that High Alert participants exhibited the greatest mean reductions in DUIC compared to both the active and passive control groups. These reductions were statistically significant when comparing all DUIC instances to the passive control, but not for the active control. No significant differences were observed in risky cannabis use. These findings suggest High Alert’s potential to reduce DUIC, warranting further investigation. Finally, Study 3 evaluated High Alert using Step 6, incorporating formative, process, outcome, and acceptability evaluations. While High Alert significantly increased DUIC knowledge and expectations of reducing DUIC compared to the active control, and received better engagement and acceptability scores, no significant differences emerged in other behavioral determinants. Process evaluations highlighted challenges in recruitment, retention, adherence, and measurement, offering insights to inform future trials. Overall, this dissertation highlights High Alert’s potential as a youth DUIC intervention and provides crucial guidance for advancing DUIC research to improve youth road safety.

Summary for Lay Audience

Young drivers in Canada report the highest rates of cannabis use and impaired driving, while showing the least concern about driving under the influence of cannabis (DUIC). Since cannabis increases crash risk, preventing youth from DUIC remains a top public health priority. This dissertation used the Intervention Mapping framework to develop, implement, and evaluate a brief smartphone program called High Alert, designed to reduce DUIC among high-risk youth in Ontario. In Study 1, the first four steps of Intervention Mapping were used to develop High Alert by combining evidence, theory, and user feedback. This process involved identifying the needs of youth (Step 1), setting clear goals for the intervention (Step 2), selecting proven methods and strategies (Step 3), and creating the program’s contents and materials (Step 4). The program was tested with five youth and five cannabis educators, whose feedback helped refine the intervention before it was pilot-tested. Study 2 applied Step 5 to test whether High Alert could reduce DUIC among 102 high-risk youth in Ontario. Results showed that participants who used High Alert had the largest reductions in DUIC compared to a group reviewing DUIC-related infographics, and a group receiving no information. These findings suggest that High Alert has the potential to reduce DUIC, but more research is needed. Finally, Study 3 evaluated High Alert using Step 6, incorporating formative, process, outcome, and acceptability evaluations. While participants in High Alert had the greatest gains in knowledge, expectations of reducing DUIC, and engagement and acceptability scores, no differences were found in other factors affecting behaviour. Process evaluations highlighted challenges in recruitment, retention, adherence, and measurement, offering insights to inform future research. Overall, this dissertation highlights High Alert’s potential as a youth DUIC intervention and provides crucial guidance for advancing DUIC research to improve youth road safety.

Creative Commons License

Creative Commons Attribution-Noncommercial 4.0 License
This work is licensed under a Creative Commons Attribution-Noncommercial 4.0 License

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