Cannabis Use and Nicotine Vaping Cessation Outcomes: A Secondary Analysis of a Randomized Clinical Trial.

Importance: Cannabis use is prevalent among adolescents and young adults who vape nicotine. It is not known if cannabis use affects nicotine vaping cessation success. Objective: To assess whether baseline frequency of cannabis use or cannabis use disorder (CUD) symptom severity was associated with nicotine vaping cessation in a randomized clinical trial. Design, Setting, and Participants: This secondary analysis of a randomized clinical trial with youth who vaped nicotine recruited at a single site in Massachusetts from June 2022 to May 2024. The trial included 3 groups receiving 12 weeks of varenicline treatment and placebo (both double-masked, paired with counseling), as well as single-masked referral to texting-app-based nicotine vaping cessation support (enhanced usual care [EUC]). Eligible participants were aged 16 to 25 years who reported vaping nicotine regularly and did not smoke tobacco. Exposure: Baseline cannabis use was assessed via self-reported number of days of cannabis use per week and with Cannabis Use Disorder Identification Test (CUDIT) scores. Main Outcomes and Measures: Biochemically verified 7-day point prevalence nicotine vaping abstinence at week 12. Logistic regression models estimated associations between baseline cannabis use and vaping abstinence. Interaction terms were evaluated to examine whether cannabis use moderated the effect of varenicline on nicotine abstinence. Results: Among the 261 participants randomized to nicotine vaping cessation treatment (mean [SD] age, 21.5 [2.0] years; 139 female [53%]), 28% (73 participants) reported no past-month cannabis use, 38% (100 participants) reported using cannabis more than 0 and less than 4 d/wk, and 30% (78 participants) reported using cannabis 4 to 7 d/wk. Cannabis use frequency was not significantly associated with nicotine vaping cessation (eg, 4 to 7 d/wk use vs no use: adjusted odds ratio [aOR], 1.14; 95% CI, 0.51-2.57; overall P = .20). Nor did cannabis frequency modify the effect of varenicline (eg, abstinence varenicline vs placebo or EUC among those with 4 to 7 d/wk use: aOR, 8.47; 95% CI, 2.78-28.25; vs among those with no use: aOR, 5.60; 95% CI, 1.97-17.06; overall interaction P = .32). Findings were similar for CUD symptom severity. Conclusions and Relevance: Among adolescents and young adults attempting to reduce or stop nicotine vaping, baseline cannabis use was not associated with nicotine vaping abstinence. Varenicline proved helpful for nicotine vaping cessation regardless of cannabis use, indicating that co-use of cannabis may not represent a barrier to successful nicotine vaping cessation treatment. Trial Registration: ClinicalTrials.gov Identifier: NCT05367492.