A randomised controlled trial of a smartphone application for people wanting to reduce or quit their use of cannabis

We are conducting a randomized controlled study of an app (Joint Control) for cannabis users wishing to reduce/quit their use of cannabis. We are comparing the full app version against a partial app version and a minimal exposure control group. The full app condition includes 4 main components: screening & feedback, goal setting, coping skills, and self-monitoring. Briefly, the screening & feedback component includes questions about age, sex, recent cannabis use, dependence, and problems. From the answers to these questions, a feedback report is generated that informs the participant about their use relative to population norms, their dependence score, and a list of reported problems. The goal-setting component allows participants to create a change plan, including a date and reduction plan. The coping skills component lists a range of coping skills, both general and specific to reasons for use. The self-monitoring tool allows participants to track their daily use, including amount used, reasons for use, and money spent. Based on this input, tracking information is graphed and summarised for participants to view when they want. Eligible participants will be sent a link to complete a baseline assessment and after completing this, will be randomised to group. Based on group allocation, participants will be sent a link to one of the three app versions: the full app, the partial app, or the control app, along with download instructions. Participants in the former two groups will be asked to use the app for four weeks (after which time access will be disabled), as much or as little as they choose. Participants' app usage will be monitored to gauge the frequency and duration that each component is accessed across the four week period. The four week period commences the day the link is sent to participants. After four weeks, all participants will receive an email with a link to complete a post-app assessment. Eight weeks following the baseline assessment, participants will be emailed a link to complete the follow-up assessment. Participants will be reimbursed for completing the post-app and follow-up assessments ($25 each). Assessments will cover general demographic information, cannabis use and severity of dependence, alcohol and other drug use, psychological distress, treatment history, self-efficacy, and readiness to change.