Psychiatry · Medical Literature
Correlates of Engagement and Associations With Outcomes in a Cannabis Harm-Reduction Mobile App for Youth With First-Episode Psychosis: Exploratory Analysis of the CHAMPS Pilot Randomized Controlled Trial.
Abstract
Continued cannabis use among young people with first-episode psychosis (FEP) has been linked to poorer clinical and functional outcomes (eg, increased symptom severity and higher relapse rates). Digital harm-reduction interventions may represent a promising, person-centered approach to reduce at-risk cannabis use behaviors in this population. However, evidence remains limited regarding which subgroups are more likely to engage with these interventions and whether specific levels of engagement are required to achieve more favorable cannabis-related outcomes. This exploratory, hypothesis-generating analysis of the CHAMPS (Cannabis Harm-Reducing App to Manage Practices Safely) pilot randomized controlled trial (RCT) evaluated a cannabis harm-reduction mobile app for youth with FEP in early intervention services (EIS). The objectives of this study were to assess engagement by examining associations between selected sociodemographic factors and module completion and to determine whether achieving specific completion thresholds was associated with improvements in cannabis-related outcomes. Cannabis-related outcomes (Marijuana Problems Scale [MPS], Protective Behavioral Strategies for Marijuana [PBSM] scores, and days of cannabis use) were self-assessed at baseline and at week 6 (primary end point), week 12, and week 18 (postrandomization). Participants were categorized into low to moderate (0-4 modules) and high (5-6 modules) completion groups, and selected sociodemographic factors were compared between groups using bivariate analyses. Mixed-effects models, adjusted for baseline values and the covariates sex and cannabis use disorder (CUD) status, were fitted to evaluate whether module thresholds were associated with improvements in cannabis-related outcomes. Data from 96 participants, including 46 in the CHAMPS+EIS arm and 50 in the EIS-only arm (1:1 ratio), were analyzed under a modified intention-to-treat principle. Individuals in the high-engagement group reported higher baseline social support and higher educational level (P=.005 and P=.01). No statistically significant associations were observed between specific module completion thresholds and cannabis-related outcomes in adjusted mixed-effects models. Participants with higher social support and higher education were more likely to engage with CHAMPS. Although descriptive analyses suggested a potential gradient of improvement with increasing module completion, no specific completion threshold was robustly associated with improvements in outcomes. Given the multifactorial nature of engagement, supporting subgroups at risk of lower app use and examining metrics beyond module completion may enhance the impact of CHAMPS. These findings are hypothesis-generating, given their exploratory nature, and require replication in a future efficacy trial.
Clinical relevance
Among youth with first-episode psychosis (FEP) enrolled in early intervention services (EIS), which sociodemographic characteristics are associated with greater engagement (module completion) with the CHAMPS cannabis harm-reduction mobile app, and does achieving a specific module-completion threshold correspond to improvements in cannabis-related outcomes? __SNAPSHOT__ {"studyDesign":"Exploratory, hypothesis-generating secondary analysis of a multi-site, two-arm, parallel-group, open-label pilot randomized controlled trial (CHAMPS pilot RCT; ClinicalTrials.gov NCT04968275)","setting":"Six specialized early intervention services (EIS) clinics for psychosis in Quebec and Nova Scotia, Canada; recruitment December 2021 to June 2023","sampleSize":"Parent pilot RCT: n=101 (CHAMPS+EIS: ~51, EIS-only: ~50); the present exploratory analysis draws from the CHAMPS intervention arm only — exact analytic n for this secondary paper not reported in the available abstract excerpt","population":"Young adults aged 18–35 years with first-episode psychosis who were actively using cannabis and were enrolled in specialized EIS; population characterized by high rates of cannabis use disorder at EIS admission and distinct clinical features including cognitive deficits","intervention":"CHAMPS (Cannabis Harm-reducing App to Manage Practices Safely): a self-guided, smartphone-delivered, brief digital psychosocial intervention grounded in the Behavior Change Wheel framework, incorporating motivational interviewing and harm-reduction principles, available in English and French, structured as six interactive modules adjunctive to standard EIS","comparator":"Not applicable for this engagement analysis (single-arm analysis of the CHAMPS intervention arm; the parent RCT comparator was EIS-only)","primaryOutcome":"Two co-primary objectives: (1) associations between selected sociodemographic factors and CHAMPS module completion (engagement); (2) whether achieving a specific module-completion threshold (≥4 of 6 modules; the pre-defined acceptability benchmark) was associated with improvements in cannabis-related outcomes measured by the Marijuana Problems Scale (MPS) and Protective Behavioral Strategies for Marijuana (PBSM) scale","followUp":"6 weeks (aligned with the parent pilot RCT assessment window); longer-term follow-up not reported in the available abstract excerpt","fundingSource":"Canadian Institutes of Health Research (CIHR; $800,000 CAD); government-funded — no industry sponsorship reported"}
Key findings
This is an exploratory, hypothesis-generating analysis; the available abstract excerpt is truncated and specific quantitative results (point estimates, confidence intervals, p-values, and effect sizes) for the sociodemographic correlates of module completion and for the completion-threshold/outcome associations are not reported in the available text and cannot be independently calculated or inferred. From the parent pilot RCT (Coronado-Montoya et al., Psychiatry Research, 2025; n=101), the overall CHAMPS module completion rate was 58.8% (meeting the pre-specified >50% acceptability threshold), and trial retention was 82.2% (meeting the >60% feasibility threshold). Signals of possible improvement in the CHAMPS+EIS arm versus EIS-only were observed for harm-reduction strategy use, motivation to change cannabis behaviors, cannabis-related problems, and cannabis-use frequency; however, these were described as descriptive signals only in a pilot context and were not powered for inferential conclusions. Whether specific sociodemographic subgroups drove differential engagement, or whether exceeding the 4-of-6 module threshold produced statistically or clinically meaningful outcome differences within the intervention arm, is the focus of the present paper — these within-arm engagement-stratified findings are not available in the provided abstract excerpt. No serious adverse events attributable to the intervention were reported in the parent trial. NNT/NNH: not calculable from available data.
Practice implications
This exploratory analysis is explicitly framed as hypothesis-generating and should be interpreted as such. It addresses an important and under-studied question in digital mental health: whether engagement dose (module completion) moderates clinical outcomes, and whether specific patient characteristics predict who will engage with app-based harm-reduction tools in a vulnerable, often treatment-resistant population. The findings — once available in full — will be informative for designing a powered efficacy RCT by helping identify who to target, what engagement benchmarks to set, and whether engagement mediates or moderates outcomes. The population studied (FEP youth, 18–35 years, Canadian EIS settings) may not generalize to older adults, those with chronic psychosis, non-cannabis substance users, or those outside organized EIS systems. This analysis is limited to the CHAMPS arm of a pilot RCT; it was not powered for causal inference and cannot establish that higher engagement caused better outcomes. Only the abstract excerpt was available at time of summary — specific results, subgroup findings, and statistical details are not reported here. Clinical practice should not change on the basis of this single exploratory analysis. __LIMITATIONS__ Exploratory, hypothesis-generating design with no pre-specified primary endpoint or multiplicity correction — all findings require independent replication before clinical application.,Small parent trial sample (n=101 total; the engagement analysis draws from the intervention arm only, further reducing analytic power), severely limiting ability to detect meaningful subgroup effects or engagement-outcome dose-response relationships.,Only abstract excerpt available at time of summary — specific point estimates, confidence intervals, p-values, and descriptions of sociodemographic correlate analyses cannot be verified or critiqued.,Single-arm secondary analysis of the intervention group precludes causal attribution — higher module completion may reflect unmeasured confounders (e.g., baseline motivation, illness severity, social support) rather than a true dose-response relationship with outcomes.,Open-label design in the parent RCT introduces performance and ascertainment bias; no blinding of participants or outcome assessors.,Six-week follow-up is brief for a population with a chronic relapsing illness; long-term engagement sustainability and durability of any cannabis-related gains are unknown.,Exclusively Canadian EIS setting (Quebec and Nova Scotia) limits generalizability to jurisdictions with different cannabis legal status, EIS structures, or cultural contexts.,Cannabis use disorder is prevalent in FEP but the CHAMPS intervention targeted those interested in harm reduction rather than abstinence — this self-selection may limit generalizability to the broader FEP cannabis-using population.,FEP populations have cognitive deficits (attention, memory) that may differentially affect app engagement in ways not fully captured by sociodemographic correlates alone.,Government-funded with no reported industry conflicts, which is a methodological strength. __BOTTOM_LINE_CATEGORY__ promising_but_preliminary __BOTTOM_LINE__ This exploratory secondary analysis of the CHAMPS pilot RCT investigates which sociodemographic factors predict app engagement and whether higher module completion is linked to better cannabis-related outcomes in youth with first-episode psychosis — a clinically important but currently unanswered question. The parent pilot RCT demonstrated that CHAMPS met pre-specified feasibility and acceptability thresholds and showed directionally favorable signals across harm-reduction outcomes, but no powered efficacy conclusions can be drawn from either the pilot or this secondary analysis. Clinicians should regard these results as hypothesis-generating data to inform a future powered RCT, not as justification for recommending or de-prioritizing the CHAMPS app in current clinical practice.