Rewards for Cannabis Abstinence-study

NCT05836207 | Recruiting

• 1 other identifier: 10390012110082
• Study Type: interventional
• Target: 154
• Locations: 1 country
• Sites: 5

Brief Summary

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: 1\. 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).

Conditions

Cannabis Use Disorder

Keywords

contingency management; cognitive behavioural therapy; CM; CBT; cost-effectiveness; youth; randomized controlled trial (RCT)

Outcome Measures

Primary Outcomes (1)

• Cannabis-abstinent days (biochemically verified)

  Number of biochemically verified cannabis-abstinent days during the 12-week intervention period

  12 weeks

Secondary Outcomes (3)

• long-term 'treatment response'

  52 weeks

• Incremental costs per treatment responder

  52 weeks

• Incremental costs per QALY

  52 weeks

Study Arms (2)

Abstinence-focused Contingency Management (CM)

EXPERIMENTAL

Youths receive 12 weeks of outpatient abstinence-focused CM consisting of providing incentives for cannabis abstinence, based on twice-weekly rapid test urinalysis.

Behavioral: Abstinence-focused Contingency Management (CM) - stand alone

Cognitive Behavioural Therapy (CBT)

ACTIVE COMPARATOR

Youths receive 12 weeks of outpatient usual care CBT consisting of once-weekly 60-minute sessions according to the standard CBT youth protocol by a trained psychologist.

Behavioral: Standard Outpatient Cognitive Behavioural Therapy (CBT)

Interventions

Abstinence-focused Contingency Management (CM) - stand alone BEHAVIORAL

Outpatient abstinence-focused contingency management (CM) as stand-alone treatment (12 weeks). Monetary incentives (vouchers) are provided for cannabis abstinence, based on twice-weekly rapid test urinalysis and an escalating reward scheme with bonuses. Urine samples are collected at the treatment centre during 15-minute sessions by a trained CM-practitioner. For each cannabis-negative urine, patients receive a monetary voucher starting at €5 and escalating to max. €35 after eight consecutive weeks of cannabis abstinence, with an additional €10 bonus after two consecutive cannabis-negative urines. The voucher-value is reset to €5 after a cannabis-positive urine test. Total earnings can be max. €675 for 12 weeks of consecutive cannabis abstinence (average: €8 p/day). Youths sign an agreement stating that vouchers must be spent on recovery-oriented goals.

Abstinence-focused Contingency Management (CM)

Standard Outpatient Cognitive Behavioural Therapy (CBT) BEHAVIORAL

CBT is the usual care first line treatment for CUD in youth, in the Netherlands. CBT for CUD is focused on learning cognitive, emotional, motivational and behavioral skills to reduce or cease cannabis use, and generally consists of 12 once-weekly 60-minute sessions and 'homework' exercise assignments, provided by a psychologist. Youths receive 12 weeks of outpatient usual care CBT consisting of once-weekly 60-minute sessions according to the standard CBT youth protocol by a trained psychologist. CBT-youths receive the same cannabis urine-testing procedures as CM-youths, but test results will not be disclosed to treatment staff or patient, and no rewards will be given for cannabis abstinence.

Cognitive Behavioural Therapy (CBT)

Eligibility Criteria

• Age: 16 Years - 22 Years
• Sex: all
• Healthy Volunteers: No
• Age Groups: Child (0-17), Adult (18-64)

You may qualify if:

• 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.

You may not qualify if:

• Health contra-indications (e.g., acute psychosis/suicidality)
• Insufficient Dutch language.

Sponsors & Collaborators

• Parnassia Addiction Research Centre: lead
• Leiden University Medical Center: collaborator
• Brijder Verslavingszorg: collaborator
• Antes: collaborator
• Novadic-Kentron: collaborator
• Amsterdam University of Applied Sciences: collaborator
• Academisch Medisch Centrum - Universiteit van Amsterdam (AMC-UvA): collaborator
• Trimbos: collaborator
• Het Zwarte Gat: collaborator

Study Sites (5)

Jellinek, Stichting Arkin B.V.

Amsterdam, 1071 KR, Netherlands

RECRUITING

IrisZorg

Arnhem, 6842 CT, Netherlands

RECRUITING

Antes Youz

Rotterdam, 3024 BH, Netherlands

RECRUITING

Brijder

The Hague, Netherlands

RECRUITING

Novadic-Kentron

Vught, 5361LX, Netherlands

RECRUITING

Study Officials

• Renske Spijkerman, PhD

  PARC

  PRINCIPAL INVESTIGATOR

• Vincent Hendriks, Prof. dr.

  PARC

  STUDY DIRECTOR

Central Study Contacts

Eva Garssen, MsC

CONTACT

+3188 358 20 34; e.garssen@brijder.nl

Renske Spijkerman, PhD

CONTACT

+31630661532; renske.spijkerman@brijder.nl

Study Design

• Study Type: interventional
• Phase: not applicable
• Allocation: RANDOMIZED
• Masking: NONE
• Purpose: TREATMENT
• Intervention Model: PARALLEL
• Sponsor Type: OTHER
• Responsible Party: SPONSOR

Study Record Dates

• First Submitted: April 18, 2023
• First Posted: May 1, 2023
• Study Start: November 21, 2023
• Primary Completion (Estimated): December 1, 2026
• Study Completion (Estimated): September 1, 2027
• Last Updated: July 31, 2025

Record last verified: 2025-07

Data Sharing

• IPD Sharing: Will share
• Shared Documents: STUDY PROTOCOL, SAP, ICF, CSR
• Time Frame: december 2028, 15 years

Locations

NL (5)