CANreduce 3.0 - a web-based self-help program for reducing cannabis use that explores the effectiveness of mindfulness and cognitive behavioral therapy approaches
| ISRCTN | ISRCTN14971662 |
|---|---|
| DOI | https://doi.org/10.1186/ISRCTN14971662 |
| ClinicalTrials.gov (NCT) | Nil known |
| Clinical Trials Information System (CTIS) | Nil known |
| Protocol serial number | 20.4.17, 10001C_192301 / 1 |
| Sponsor | University of Zurich |
| Funder | Schweizerischer Nationalfonds zur Förderung der Wissenschaftlichen Forschung |
- Submission date
- 09/09/2021
- Registration date
- 09/09/2021
- Last edited
- 06/12/2022
- Recruitment status
- No longer recruiting
- Overall study status
- Completed
- Condition category
- Mental and Behavioural Disorders
Plain English summary of protocol
Background and study aims
In European countries, including Switzerland, as well as in many states worldwide, cannabis is the most widely used psychoactive substance (a chemical known to change brain function) after alcohol and tobacco. Although approximately one in ten users develop serious problems of dependency, only a small number attend outpatient addiction counseling centers. The offer of a web-based self-help program could potentially also reach those users who hesitate to approach such treatment centers and help them to reduce their cannabis use.
This study will test the effectiveness of two versions of a web-based self-help intervention (program) in reducing cannabis use in problematic users. One version is based on classical therapy (cognitive behavioral therapy) and one is based on mindfulness. A third condition is a waiting list control group.
Who can participate?
Adults (aged 18 years or above) who can read and write in German and have used cannabis at least once a week during the last 30 days.
What does the study involve?
Participants are randomly allocated to one of three groups. The two intervention groups consist of a 6-week, web-based self-help program (CANreduce) with a consumption diary, eight modules designed to help people to reduce their cannabis intake based on the principles of motivational interviewing, self-control practices, and methods of cognitive behavioural therapy (arm 1) or a mindfulness-based therapy (arm 2). The waiting control group are placed on a waiting list; after 6 months they can start the program, too. All participants are followed up after 6 weeks, 3 and 6 months to see whether they have reduced their cannabis use.
What are the possible benefits and risks of participating?
A possible benefit to participation is using less cannabis. Possible risks include experiencing mild cravings and depression.
Where is the study run from?
Swiss Research Institute for Public Health and Addiction (ISGF) (Switzerland)
When is the study starting and how long is it expected to run for?
April 2020 to March 2024
Who is funding the study?
Swiss National Science Foundation
Who is the main contact?
Prof. Dr Michael Schaub, michael.schaub@isgf.uzh.ch
Contact information
Scientific
Konradstrasse 32
Zürich
8005
Switzerland
 ORCID ID |
0000-0002-8375-4005 |
|---|---|
| Phone | +41 44 448 11 65 |
| michael.schaub@isgf.uzh.ch |
Study information
| Primary study design | Interventional |
|---|---|
| Study design | Interventional randomized controlled trial |
| Secondary study design | Randomised controlled trial |
| Study type | Participant information sheet |
| Scientific title | CANreduce 3.0 - Randomized controlled trial testing the effectiveness of two different versions (mindfulness and CBT) of an adherence-focused web-based self-help intervention to reduce cannabis use in frequent cannabis users |
| Study acronym | CANreduce 3.0 |
| Study objectives | Current study hypothesis as of 24/01/2022: 1. A web-based self-help program with focus on mindfulness (arm 1) is more effective than the waiting list control condition (study arm 3) in reducing cannabis use in frequent cannabis users 2. A web-based self-help program with focus on cognitive behavioral therapy (arm 2) is more effective than the waiting list control condition (study arm 3) in reducing cannabis use in frequent cannabis users 3. A web-based self-help program with focus on mindfulness (arm 1) is at least as effective as one with focus on cognitive behavioral therapy (arm 2) in frequent cannabis users. Previous study hypothesis: 1. A web-based self-help program with focus on mindfulness (arm 1) is more effective than the waiting list control condition (study arm 3) in reducing cannabis use in cannabis misusers 2. A web-based self-help program with focus on cognitive behavioral therapy (arm 2) is more effective than the waiting list control condition (study arm 3) in reducing cannabis use in cannabis misusers 3. A web-based self-help program with focus on mindfulness (arm 1) is similarly effective as one with focus on cognitive behavioral therapy (arm 2) in cannabis misusers. |
| Ethics approval(s) | Approved 22/04/2020, Ethics Committee, Faculty of Arts and Social Science, University Zurich (Institute of Psychology, Binzmühlestrasse 14, Box 22, 8050 Zurich, Switzerland; +41 (0)44 635 74 70; k.oberauer@psychologie.uzh.ch), ref: 20.4.17 |
| Health condition(s) or problem(s) studied | Frequent cannabis use |
| Intervention | Current interventions as of 24/01/2022: The three-arm randomized controlled trial aims to test the effectiveness of a newly developed integrated mindfulness-based minimally guided self-help Internet intervention (Arm 1) and a cognitive-behavioral minimally guided self-help Internet intervention (reference product; Arm 2) with a control condition (Arm 3) in 630 individuals with frequent cannabis use. Moreover, we will explore similarities between the main intervention (arm 1) and the reference product (arm 2) for the effect size of the difference between the two study arms with confidence interval approaches including a priori set equivalence margin. In addition, the project intends to identify and compare relevant predictors of retention, adherence, and treatment outcomes for the two main intervention arms. The primary outcome is the number of days of cannabis use in the last 30 days. Participants are randomly allocated to one of three arms: 1. Intervention 1: Web-based self-help program with focus on mindfulness 2. Intervention 2: Web-based self-help program with focus on cognitive behavioral therapy 3. Control group: Waiting list CANreduce is an automated web-based self-help tool based on classical CBT approaches (expanded with mindfulness for this trial) for treating adults with frequent cannabis use. It will take 6 weeks and consists of a consumption diary, eight modules designed to reduce cannabis use based on the principles of motivational interviewing, self-control practices, and methods of cognitive-behavioural therapy (strategies for goal achievement, identifying risk situations, dealing with cannabis craving, dealing with relapses, working on needs, saying “no” to foster refusal skills, dealing with burdens, preserving achievements). The control condition is a waiting list. After 6 months they will be given the opportunity to start the self-help program (study arm 1). The masking technique will be single-blind, insofar that participants are only informed that "two different interventions" are being studied but not that they are mindfulness and CBT based. However, they will know if they have been assigned to the waiting list. Once participants have completed their baseline assessment, they will be randomly assigned by a software-generated random number to one of the three groups. Previous interventions: The three-arm randomized controlled trial aims to test the superiority of a newly developed integrated mindfulness-based minimally guided self-help Internet intervention (Arm 1) and a cognitive-behavioral minimally guided self-help Internet intervention (reference product; Arm 2) with a control condition (Arm 3) in 630 individuals who abuse cannabis. Moreover, we will explore similarities between the main intervention (arm 1) and the reference product (arm 2) for the effect size of the difference between the two study arms with confidence interval approaches including a priori set equivalence margin. In addition, the project intends to identify and compare relevant predictors of retention, adherence, and treatment outcomes for the two main intervention arms. The primary outcome is the number of days of cannabis use in the last 30 days. Participants are randomly allocated to one of three arms: 1. Intervention 1: Web-based self-help program with focus on mindfulness 2. Intervention 2: Web-based self-help program with focus on cognitive behavioral therapy 3. Control group: Waiting list CANreduce is an automated web-based self-help tool based on classical CBT approaches for treating cannabis dependence. It will take 6 weeks and consists of a consumption diary, eight modules designed to reduce cannabis use based on the principles of motivational interviewing, self-control practices, and methods of cognitive behavioural therapy ( strategies for goal achievement, identifying risk situations, dealing with cannabis craving, dealing with relapses, working on needs, saying “no” to foster refusal skills, dealing with burdens, preserving achievements). The control condition is a waiting list. After 6 months they will be given the opportunity to start the self-help program. The masking technique will be single-blind, insofar that participants are only informed that "two different interventions" are being studied but not that they are mindfulness and CBT based. However, they will know if they have been assigned to the waiting list. Once participants have completed their baseline assessment, they will be randomly assigned by a software generated random number to one of the three groups. |
| Intervention type | Behavioural |
| Primary outcome measure(s) |
Number of days of cannabis use in the last 30 days measured using self-report at baseline, after 6 weeks, and at 3 and 6 months follow-up. |
| Key secondary outcome measure(s) |
Current secondary outcome measures as of 24/01/2022: |
| Completion date | 31/03/2024 |
Eligibility
| Participant type(s) | |
|---|---|
| Age group | Adult |
| Lower age limit | 18 Years |
| Sex | All |
| Target sample size at registration | 630 |
| Key inclusion criteria | Current inclusion criteria as of 24/01/2022: 1. Cannabis use of at least once a week 30 days prior to study entry 2. At least 18 years old 3. At least weekly internet access and a valid email address and phone number 4. Informed consent (via a web form) Previous inclusion criteria: 1. Cannabis use of at least once a week 30 days prior to study entry 2. At least 18 years old 3. At least weekly internet access and a valid email address |
| Key exclusion criteria | 1. Current pharmacological psychiatric disease or history of psychosis, schizophrenia, bipolar type I disorder or significant current suicidal thoughts 2. Use of other pharmacological and psycho-social treatments for cannabis use disorders 3. Inability to read or write in German |
| Date of first enrolment | 13/09/2021 |
| Date of final enrolment | 13/09/2023 |
Locations
Countries of recruitment
- Austria
- Germany
- Switzerland
Study participating centre
Zürich
8005
Switzerland
Results and Publications
| Individual participant data (IPD) Intention to share | Yes |
|---|---|
| IPD sharing plan summary | Available on request |
| IPD sharing plan | Fully anonymized data will be shared with qualified and trusted individuals for further use upon request (for example, for individual-patient data metanalyses). michael.schaub@isgf.uzh.ch |
Study outputs
| Output type | Details | Date created | Date added | Peer reviewed? | Patient-facing? |
|---|---|---|---|---|---|
| Protocol article | 24/03/2022 | 06/12/2022 | Yes | No | |
| Participant information sheet | Participant information sheet | 11/11/2025 | 11/11/2025 | No | Yes |
| Study website | Study website | 11/11/2025 | 11/11/2025 | No | Yes |
Editorial Notes
06/12/2022: Publication reference added.
24/01/2022: The following changes were made to the trial record:
1. The scientific title was changed from 'CANreduce 3.0 - Randomized controlled trial testing the effectiveness of two different versions (mindfulness and CBT) of an adherence-focused web-based self-help intervention to reduce cannabis use in problematic cannabis users' to 'CANreduce 3.0 - Randomized controlled trial testing the effectiveness of two different versions (mindfulness and CBT) of an adherence-focused web-based self-help intervention to reduce cannabis use in frequent cannabis users'.
2. The study hypothesis, ethics approval, interventions, secondary outcome measures and inclusion criteria were updated.
3. The condition was changed from 'Cannabis use disorder' to 'Frequent cannabis use'.
10/09/2021: Internal review.
09/09/2021: Trial's existence confirmed by University of Zurich
