Overview
The goal of this clinical trial is to investigate the (cost-)effectiveness of contingency management (CM) compared with Cognitive Behavioural Therapy (CBT) for the treatment of cannabis use disorder (CUD) in youth (16-22 years).
The main questions it aims to answer are:
- What is the efficacy of 12 weeks outpatient CM versus CBT in youths with a CUD, in terms of cannabis abstinence during the intervention period?
- What is the long-term efficacy of CM versus CBT at 6- and 12-months follow-up (FU)?
- What is the cost-effectiveness of CM versus CBT at 12-months FU from a societal perspective?
Study hypotheses are:
- CM will result in more cannabis-abstinent days than CBT during the intervention; 2. CM is more effective and cost-effective than CBT at 12 months follow-up.
Eligible patients (n=154) will be randomly assigned to either 12 weeks of outpatient CM or CBT. Assessments are conducted by trained research-assistants at baseline, after 6, 12, 26 and 52 weeks, and twice-weekly during treatment and consist of questionnaires, a computer task and collection of urine samples. Primary endpoint is the number of biochemically verified cannabis abstinent days in the 12-week treatment period. Key secondary endpoint: Treatment response: 50% or more reduction in cannabis use days in the past 4 weeks, compared with baseline.
The primary outcome will be modelled in the intention-to-treat population in a (negative binomial) regression analysis with treatment group as independent variable and stratification variables as covariates.
Cost-effectiveness and cost-utility analysis (CEA; CUA) will be performed from a societal perspective. CEA: Treatment response is the central clinical endpoint for calculations of incremental costs per responder. CUA: Incremental costs per QALY (based on EuroQoL).
Eligibility
Inclusion Criteria:
- Youths (16-22 years) seeking treatment for a primary CUD
- Regular cannabis use (≥14 days) in past 4 weeks
- Intention to cease cannabis use during intervention
- Able and willing to attend the treatment center and submit urine samples under supervision twice-weekly
- Informed consent.
Exclusion Criteria:
- Health contra-indications (e.g., acute psychosis/suicidality)
- Insufficient Dutch language.