Testing the Effects of Cann'App, a Digital Intervention for Cannabis Harm Reduction

Official title

Testing the Effects of a Digital Intervention for Cannabis Harm Reduction - The Cann'App Fractional Factorial Randomized Controlled Trial

Overview

The goal of this clinical trial is to learn if a digital web application can prevent the risks related to cannabis use among adult regular cannabis users who are enrolled in a pilot trial for cannabis sales regulation conducted in Lausanne, Switzerland (i.e., Cann-L study) and have agreed that their data were used in other studies. The main question it aims to answer is: Do participants who have access to the intervention modules of the web application raise their use of protective behavioral strategies to lower cannabis-related risks? Researchers will compare the intervention modules to a control module (i.e., information on cannabis-related risks and harm reduction) to see if the web application works to prevent the risks related to cannabis use. They will also compare intervention modules across each other to see whether one works better than another. Participants will: * Create a user account in the web application * Access the web application using a laptop, tablet or smartphone * Use the web application as they wish throughout the duration of the study * Complete the regular Cann-L study questionnaires every six months, which will be used to measure their cannabis use and related risks.

Interventions

• Behavioral Personalized Feedback on Cannabis Protective Behavioral Strategies, Cannabis Use, Cannabis Expenditures, and Cannabis-Related Consequences (PF)
  PF comprises the following content: * Self-reported PBS questionnaire, personalized feedback on PBS, possibility to select strategies to start using or use more often, possibility to set a reminder to use PBS strategies. * Short questionnaire on cannabis use (frequency/number of hours under the influence) and normative feedback on participant's cannabis use as compared to people of same age and gender in the general population and among Cann-L participants. * Question on money spent for cannabi
• Behavioral Imagining the Future Using Counterfactual Thinking and Episodic Future Thinking (IMAGIN)
  Two-task intervention including: 1. Counterfactual thinking: * Description of a recent negative situation related to cannabis use encountered by the participant * Identification of a preventive strategy that would have addressed this situation * Writing a sentence formatted as "If only +preventive strategy, then + description on how the specific past problem would have improved" * Assessment of participant's intention and confidence in using the preventive strategy * Imagining a
• Behavioral Behavioral Economics-Informed Exercises to Increase Motivation to Engage in Substance-Free Activities (SFAS)
  SFAS includes: * A questionnaire on how participant value different aspects of their life, and feedback on valued domains. * Two open-ended questions on short- and long-term life goals. * A questionnaire assessing time allocation (hours per week allocated to different activities, e.g. socializing, working, etc.), and personalized feedback including the time spent using substances and recovering from their effects. * Gamified exercise to imagine allocating time in a different way. * List of subs
• Behavioral Information
  Minimal intervention (Control Intervention), consisting of simple, text-only web pages containing information on cannabis effects and health-related risks, cannabis consumption modes, cannabis harm reduction and protective behavioral strategies, as well as hyperlinks to additional resources and online help.

Primary outcome measures

• Frequency of Protective Behavioral Strategies for Marijuana Use as Measured by the PBSM-17 Short Form Scale [Time frame: This outcome will be assessed at 1- and 7-month follow-up.]

Secondary outcome measures (2)

• Cannabis Use Frequency [Time frame: This outcome will be measured at 1- and 7-month follow-up.]
• Number of Hours High on a Typical Day [Time frame: This outcome will be measured at 1- and 7-month follow-up.]

Eligibility criteria

Inclusion criteria

• Eligible participants will be those included in the pilot trial of cannabis sales regulation in Lausanne, Switzerland (Cann-L study).

Inclusion criteria in Cann-L study are:

• being adult (>18 years old),
• having current cannabis use (i.e., use at least once a month over the last 6 months)
• living in the city of Lausanne. To enter the study, they complete an entry assessment verifying their age and proof of residence, and confirming that they have current cannabis use.

Exclusion criteria

• Cann-L exclusion criteria comprise:
• being younger than 18 years old,
• being pregnant or breastfeeding,
• having a health condition contraindicating the use of cannabis (e.g., severe psychiatric disorder).

The consent to participate in the Cann-L parent trial comprises an option to be contacted to participate in sub-studies, including studies on prevention measures. All participants having accepted to be so contacted will be proposed to participate in the present study.

Therefore, additional exclusion criteria for the present study include:

• not providing informed consent to participate in sub-studies, including studies on prevention measures,
• not providing informed consent to participate in the present study.

Criteria are shown verbatim from the registry (in English). Final eligibility is always assessed by the study center.

Healthy volunteers: No

Study design

Allocation

Randomized

Model

Factorial

Masking

Triple blind

Primary purpose

Prevention

Study locations

Switzerland · 1 center

• Lausanne University Hospital — Lausanne

Identifiers

NCT: NCT07157540 · 2025-00428 · 10001E_220072

Primary sources (government registries)

• ClinicalTrials.gov (US NIH)

View this study on ClinicalTrials.gov ↗