The research aims of the “Characterization of the pattern of consumption and withdrawal syndrome of dual use of cannabis and/or tobacco in people with CUD who start cessation treatment: DuCATA study” can be described, indicating the studies in which each objective falls.

Determinate the treatment preferences of individuals with CUD, based on age (18-34 years and 35 years or older) and sex, for the design of a gamified web app.

Examine the consumption patterns of cannabis and tobacco products among individuals seeking help to reduce and quit their cannabis use. This includes considering structural determinants of inequality (age, sex, social class or educational level, and territory) and clinical history (use of other substances, psychiatric comorbidity, etc), and identifying different typologies of cannabis-tobacco users, such as concurrent use, sequential use, asynchronous use, and exclusive cannabis use.

Analyze changes in tobacco use during the cannabis treatment process based on the identified typologies of cannabis-tobacco users and the level of clinical care they receive (with or without assistance for quitting tobacco).

Validate the “Cannabis Withdrawal Checklist” scale in the Spanish population and explore the relationship between the intensity and duration of craving and abstinence.

Describe and predict the likelihood of cannabis and tobacco abstinence based on consumption patterns (eg, type of consumption), psychological factors (trait and state), and contextual factors (eg, environment, social influences, and activities) while considering structural determinants of inequality.

Investigate the clinical experiences of individuals undergoing treatment for CUD, taking into account their typologies, age, and sex.

In conclusion, the “DuCATA study” aims to achieve 6 objectives across different studies. These objectives involve understanding treatment preferences for CUD through a gamified web app, examining the patterns of cannabis and tobacco use among individuals seeking help, validating assessment scales, and exploring clinical experiences.

The objective is to develop a gamified web app co-designed by the research team and potential users.

This study uses a participatory action approach, using focus groups to explore the perspective of potential users and ensure high usability and adherence. Participants include 10 cannabis-tobacco users or former users selected from 3 substance abuse programs (SAP) in Barcelona province, based on purposive sampling and inclusion criteria of 18 years of age or older, undergoing treatment for cannabis use, and owning a smartphone. The focus groups consist of 5 participants, homogeneously grouped by sex and age profiles, with sessions lasting 60 to 90 minutes. Both focus groups and participatory activities are conducted, engaging participants in-person discussions and interactive activities while recording conversations for analysis. Each group is led and coordinated by 3 individuals, including an expert in qualitative research, a web app developer, and a project investigator member.

Purposive sampling is used to recruit participants meeting the inclusion criteria. The eligibility criteria are determined by the clinicians of the SAP centers that collaborate in the study.

Focus groups and participatory activities, were used, consisting of 2 pilot sessions (where a homemade board game was used to explore participants’ gaming preferences), and 3 participatory sessions (including 2 exploratory sessions with clinicians and former cannabis users to profile this population, and a third session of in-depth interviews to explore into participants’ personal experiences overcoming cannabis use). These sessions were conducted to gather pertinent information for web app design. Each session involved discussions among participants to explore various themes, such as users’ experiences with gamified web apps, expectations and preferences regarding app features, preferred game types, and personal experiences related to cannabis use.

Transcriptions of focus group discussions and participatory activities serve as primary data for analysis, involving familiarization, coding, theme development, data interpretation, and validation. The thematic categorical content analysis will be conducted using ATLAS.ti (ATLAS.ti Scientific Software Development GmbH). Based on these findings, a web app prototype is developed.

With input from participating groups, an external company experienced in gamified web app design, along with patients and researchers, designs the web app prototype. The prototype incorporates variables of interest in an engaging manner. The same participants involved in co-design will pilot the web app.

The aim is to monitor patterns of use of cannabis and tobacco, withdrawal symptoms, abstinence, and other indicators among cannabis users.

This study uses a prospective longitudinal follow-up approach. The inception cohort consists of cannabis users attending SAP centers in the province of Barcelona during 2023 to initiate treatment for their disorder.

All SAP coordinators in the province of Barcelona (48 centers) are contacted. We plan to recruit 10 to 14 centers, each recruiting 8 to 12 participants on average.

Clinicians recruit individuals who have commenced reducing or quitting cannabis use attending in SAP. Participants are invited to self-manage and self-report their cannabis-tobacco use and symptomatology through a gamified web app and an external software that sends questionnaires regularly (every 6 days) to monitor other behavioral and contextual aspects. Before launching the study, the recruitment protocol is piloted in 3 SAP centers to make necessary adjustments for ease of recruitment by clinicians and increased acceptability among eligible participants.

The cohort members are cannabis users beginning treatment for CUD at SAP centers in Catalonia.

Participants must be older than 18 years of age, daily cannabis users regardless of tobacco consumption pattern or type, in treatment for cannabis use or another substance in an SAP, followed by collaborating clinicians, own a smartphone or computer with an internet connection, commit to daily participation in the web app for 6 weeks, have and use WhatsApp (Meta Platforms) and email, and provide informed consent.

Individuals unable to guarantee 6 weeks of follow-up, those without access to a device for 6 weeks, inability to read and understand Spanish, and moderate or severe cognitive limitations and severe psychopathology, which will be assessed by clinicians during consultation at the time of participant invitation.

According to a recent meta-analysis, the probability of cannabis cessation in this patient population treated using diverse therapeutic approaches is relative risks (RR)=1.48 (28). Given its heterogeneity, we will use a more conservative estimate (RR=1.20). Thus, with an alpha risk of 0.05, a beta risk of 0.20 in a bilateral contrast, and accounting for 20% losses to follow-up, 282 participants will be required. Approximately 2000 people start treatment for cannabis use each year in Catalonia [28], making it feasible to recruit 282 participants within a 1-year period.

The end points are (1) variables reported every 3 days during 6 weeks within the web app and (2) variables collected in the external software at baseline and every 6 days.

Cannabis use is determined based on the (1) consumption of cannabis in the last 48 hours (yes or no), reduction of cannabis in the last 48 hours (yes or no), and cannabis abstinence or reduction requiring a cannabis withdrawal test and (2) cannabis product used (hashish, marijuana, etc), mode of administration (smoking, snorting, ingestion, etc), frequency of cannabis use in the last month and week, type of use (alone, accompanied, and both), and reasons for use (addiction, recreational, social, sleeping, etc).

Tobacco use is determined based on (1) tobacco consumption in the last 48 hours (yes or no) and (2) pattern of tobacco use—type of tobacco products (manufactured cigarettes, roll-your-own, electronic cigarettes, heated tobacco, or similar), frequency of use (daily and occasional), number of units (cigarettes, etc), and nicotine dependence measured using the Heavy Smoking Index (0 to 6), classified as low (0-2), moderate (3-4), and high (5-6) [29,30].

If abstinent of both substances we will ask for a CO measurement test (performed by their clinician and introduced in the software; yes or no).

Cannabis-tobacco users will be classified as concurrent use, sequential concurrent use, asynchronous concurrent use, and exclusive cannabis use.

The ASE model variables are attitudes, subjective norms, and self-efficacy.

Motivation to quit was measured on a Likert scale, psychological factors (states of change or readiness to quit cannabis and tobacco and psychological distress) [31]. Psychological distress was measured by using the General Health Questionnaire (GHQ-12) [32].

The self-perceived health status will be assessed based on “How would you say your general health is?” (excellent, very good, good, fair, fair, or poor).

Self-efficacy is defined as the individual’s confidence to quit cannabis and tobacco [33]. This will be assessed by asking participants, “To what extent do you feel capable of quitting cannabis consumption?” using a Likert scale ranging from 0 to 10 (0= very low to 10= very high).

Sociodemographic variables are (baseline) sex, age, education level, employment status, and occupation. Mental and physical health measures are mental illness presence and comorbidities. Centers are where care is received. The family environment is cohabitation, socioeconomic level, and so forth.

To test the acceptability, appropriateness, and feasibility besides using the qualitative methodology explained, we will quantitatively measure these dimensions among all the participants enrolled in the cohort. We will use the scale developed by Weiner et al [34] that consists of 12 items scored from 1 (completely disagree) to 5 (completely agree). This evaluation will be conducted at the end of the follow-up period (6 weeks), and we will collect this information using a customized questionnaire administered via phone call or text message. Additionally, we will assess other implementation outcomes at the end of study 2 by gathering data on (1) acceptability—the number of individuals who accept or decline to participate in the study; (2) fidelity or adherence—the duration of participants’ usage of the web app, time devoted to playing, number of completed sessions, and so forth; and (3) satisfaction—participants’ opinions about the proposed web app. These variables will be measured using the metadata of the web app (encrypted).

Clinicians verify participant eligibility using a checklist of inclusion and exclusion criteria. They provide oral and written information to potential participants through a leaflet containing study details and information about the study sponsors. Potential participants are informed about the study objectives, procedures, potential risks, benefits, confidentiality measures, and their right to withdraw at any time. This process ensures that only eligible participants who meet the criteria are enrolled in the study.

Additionally, clinicians show a short video explaining the purpose of the research and soliciting participants’ collaboration (available on YouTube [35]). If participants agree to participate, they sign the informed consent and then complete a questionnaire with brief personal information (telephone number, email, name, and national identity document). Subsequently, participants register on the web app and engage with the game daily.

For independent variables, a descriptive analysis will be conducted, including frequencies, percentages, and their 95% CIs. To assess effectiveness measures such as changes in cannabis-tobacco use, withdrawal syndrome, and treatment adherence, frequencies and percentages will be described for baseline and main assessment end points according to the four patterns of cannabis use and they are (1) concurrent, (2) sequential concurrent, (3) asynchronous concurrent, and (4) exclusive cannabis. Incidence rates of abstinence and symptomatology will be calculated for the same assessment end points across the 4 patterns. The RR of quitting or reducing cannabis and tobacco, as well as quit attempts for both substances (95% CI), adjusted for independent variables, and initial consumption pattern, will be calculated using Cox or Poisson robust regression models. Predictive analysis techniques including logistic regression and random forest will be used to model the probability of events occurring based on other factors. Time series analysis will be used to observe consumption trends during the follow-up, and survival analysis of recurring events will be conducted to observe abstinence or reduction processes among participants.

For all analyses, SPSS (IBM Corp) for Windows version 21, Python (version 3; Python Software Foundation), R (version 4.0.3; R Core Team), and scikit-learn will be used. The level of significance will be set at 5% (P<.05).

The objective is to evaluate the acceptability of the web app and investigate participant and clinician experiences during study 2, focusing on implementation outcomes.

The methodology used is a qualitative phenomenology study using participatory groups.

Participants will be selected from study 2 cohort members based on their web app usage experience. A total of 4 groups comprising 5-7 participants each are anticipated.

Purposive sampling will be used, targeting individuals meeting the inclusion criteria and having engaged with the web app. Homogeneity criteria will be applied to ensure diversity across fidelity levels and gender—group 1: high fidelity male users; group 2: low fidelity male users; group 3: high fidelity female users; and group 4: low fidelity female users.

The main themes are exploration of barriers and opportunities encountered during web app usage, assessment of the use of web app monitoring for cannabis or tobacco use and mood, and identification of preferred and disliked features of the web app.

Focus groups are expected to last between 60 and 90 minutes. Conversations will be recorded to facilitate transcription and analysis while ensuring confidentiality. Each group will be facilitated by 2 individuals, including an expert in qualitative research and a project investigator.

Transcribed data will undergo analysis involving familiarization, coding, theme development, interpretation, and validation; the thematic categorical content analysis will be conducted using ATLAS.ti. Insights garnered will inform the refinement of a web app prototype.