The (cost-)effectiveness of contingency management for cannabis use disorder in youth: A randomized controlled trial

Background

Most treatment demand in Dutch youth addiction care concerns a primary cannabis use disorder (CUD). Usual care cognitive behavioral therapy (CBT) shows limited efficacy and considerable relapse rates. Contingency Management (CM) has shown robust efficacy across a range of substance use disorders in adults but remains relatively unexplored in CUD in adolescents. CM focuses on reinforcing intended behavior – in this study ceasing cannabis use – by intensively and systematically rewarding this behavior. Twice per week youth provide urine samples to test cannabis abstinence by urinalysis. For each cannabis-negative urine, youth receive a monetary voucher starting at 5 euro and escalating to max. 35 euro, resulting in a total earning of max. 675 euro in case of 12 weeks of consecutive cannabis abstinence. This randomized controlled trial (RCT) is the first trial worldwide which aims to compare the effectiveness and cost-effectiveness of CM as a stand-alone treatment with usual care CBT in youth. 

Methods

In this RCT, 154 eligible youth (16 to 22 years) with a primary CUD and the intention to cease cannabis use during the intervention are randomly assigned to 12 weeks outpatient CM or CBT. Study assessments take place at baseline, week 6 and week 12 (end-of-treatment), and at 26 and 52 weeks post baseline (follow-up). The primary outcome measure is days of cannabis abstinence during the 12 weeks intervention period, based on self-report, verified by twice-weekly urinalysis. Key secondary outcome measures are (1) (long-term) ‘treatment response’ (days of cannabis abstinence) at week 12, week 26, and week 52, and (2) the cost-effectiveness of CM versus CBT in terms of incremental costs per treatment responder and per quality-adjusted life year (QALY) in the 52 weeks study period. Furthermore, the efficacy of CM versus CBT will be investigated in terms of mental health, social functioning and quality of life, and potential moderating effects of baseline impulsive decision-making and various factors like concurrent treatment for comorbid psychiatric disorders, gender, age, ethnicity and socioeconomic status (SES) will be explored.

Results

Our main hypotheses are (1) CM will outperform CBT in terms of both short- and long-term efficacy, (2) CM will outperform CBT in terms of cost-effectiveness, and (3) CM will be more efficacious than CBT in youths with high versus low baseline impulsive decision-making during treatment.

Conclusions

Inclusion of participants has started in November 2023 and will last approximately 24 months. First results pertaining to the efficacy and cost-effectiveness of CM versus CBT are expected to be published in 2026.