Theory-based smoking cessation interventions for young adults: A systematic review of randomized controlled trials

Young adulthood is a critical developmental window for establishing long-term smoking behaviors, yet cessation success remains low due to limited access to theory-based interventions. This systematic review evaluated the effectiveness of behavioral theory-informed smoking cessation interventions targeting this group.

A systematic search was conducted in PubMed, PsycINFO, Scopus, and the Cochrane Library for English-language randomized controlled trials (RCTs) published between 2010 and 2025. Included studies evaluated cessation interventions for young adults (18-29 years) and explicitly described their theoretical framework. Primary outcome was abstinence. Screening, selection, and data extraction followed standard systematic review procedures. Risk of bias was assessed using the Joanna Briggs Institute Appraisal Tool. A narrative synthesis was performed due to heterogeneity.

Fourteen RCTs (11,038 participants) across seven countries were included, though only five specifically targeted young adults (18-29 years). Interventions spanned 3 to 40 weeks via face-to-face, app, and text-based delivery. Frameworks included SCT, TTM, SDT, and CBT. CBT and SDT produced the most sustained outcomes, with CBT showing robust effects (e.g., OR=4.68 at 26 weeks). SCT demonstrated mixed results: personalized formats were effective (OR=2.03), while non-personalized digital messaging was limited (OR=0.36). Digital and COM-B-based interventions yielded high engagement, but lower long-term maintenance compared to intensive, face-to-face programs. Most studies (71 %) had moderate risk of bias, with unclear allocation concealment and limited blinding.

Theory-based interventions support smoking cessation among young adults, yet their long-term efficacy is often limited by high relapse rates. While multimodal strategies combining digital scalability with more intensive, face-to-face support appear most promising, sustained abstinence remains challenging to achieve. Future research should prioritize well-powered longitudinal trials that identify and test active behavioral mechanisms of change and directly evaluate integrative theoretical frameworks to improve long-term cessation outcomes during this critical developmental period.