%0 Journal Article
%@ 1438-8871
%I JMIR Publications
%V 23
%N 4
%P e27463
%T CANreduce 2.0 Adherence-Focused Guidance for Internet Self-Help Among Cannabis Users: Three-Arm Randomized Controlled Trial
%A Baumgartner,Christian
%A Schaub,Michael Patrick
%A Wenger,Andreas
%A Malischnig,Doris
%A Augsburger,Mareike
%A Walter,Marc
%A Berger,Thomas
%A Stark,Lars
%A Ebert,David Daniel
%A Keough,Matthew T
%A Haug,Severin
%+ Swiss Research Institute for Public Health and Addiciton, University of Zurich, Konradstrasse 32, Zürich, 8005, Switzerland, 41 444481160, christian.baumgartner@isgf.uzh.ch
%K cannabis
%K common mental disorders
%K adherence
%K social presence
%K internet
%K cognitive behavioral therapy
%K motivational interviewing
%K therapy
%K mental health
%K mental disorder
%K adherence
%K guidance
%K self-help
%K drug abuse
%K randomized controlled trial
%D 2021
%7 30.4.2021
%9 Original Paper
%J J Med Internet Res
%G English
%X Background: Despite increasing demand for treatment among cannabis users in many countries, most users are not in treatment. Internet-based self-help offers an alternative for those hesitant to seek face-to-face therapy, though low effectiveness and adherence issues often arise. Objective: Through adherence-focused guidance enhancement, we aimed to increase adherence to and the effectiveness of internet-based self-help among cannabis users. Methods: From July 2016 to May 2019, cannabis users (n=775; male: 406/575, 70.6%, female: 169/575, 29.4%; age: mean 28.3 years) not in treatment were recruited from the general population and were randomly assigned to (1) an adherence-focused guidance enhancement internet-based self-help intervention with social presence, (2) a similar intervention with an impersonal service team, and (3) access to internet as usual. Controls who were placed on a waiting list for the full intervention after 3 months underwent an assessment and had access to internet as usual. The primary outcome measurement was cannabis-use days over the preceding 30 days. Secondary outcomes included cannabis-dependence severity, changes in common mental disorder symptoms, and intervention adherence. Differences between the study arms in primary and secondary continuous outcome variables at baseline, posttreatment, and follow-up were tested using pooled linear models. Results: All groups exhibited reduced cannabis-use days after 3 months (social presence: –8.2 days; service team: –9.8 days; internet as usual: –4.2 days). The participants in the service team group (P=.01, d=.60) reported significantly fewer cannabis-use days than those in the internet as usual group; the reduction of cannabis use in the social presence group was not significant (P=.07, d=.40). There was no significant difference between the 2 intervention groups regarding cannabis-use reduction. The service team group also exhibited superior improvements in cannabis-use disorder, cannabis-dependence severity, and general anxiety symptoms after 3 months to those in the internet as usual group. Conclusions: The adherence-focused guidance enhancement internet-based self-help intervention with an impersonal service team significantly reduced cannabis use, cannabis-use disorder, dependence severity, and general anxiety symptoms. Trial Registration: ISRCTN Registry ISRCTN11086185; http://www.isrctn.com/ISRCTN11086185 
%M 33929333
%R 10.2196/27463
%U https://www.jmir.org/2021/4/e27463
%U https://doi.org/10.2196/27463
%U http://www.ncbi.nlm.nih.gov/pubmed/33929333