Abstract
IMPORTANCE: Smoking prevalence remains alarmingly high among low-income adults, who face disproportionate barriers to cessation and experience unique smoking lapse triggers. OBJECTIVE: To compare the efficacy of the Smart-T smartphone intervention, featuring tailored, just-in-time adaptive interventions, with the National Cancer Institute QuitGuide intervention in supporting smoking cessation among adults with low income. DESIGN, SETTING, AND PARTICIPANTS: This randomized clinical trial was conducted from August 2019 to November 2023 among US adults with household incomes below 200% of the federal poverty line. Participants were randomized to Smart-T or QuitGuide and followed-up for 27 weeks. Data were analyzed from July 2024 to March 2025. INTERVENTIONS: Both groups received nicotine replacement therapy. The Smart-T intervention provided ecological momentary assessment-driven tailored feedback and prompts to use nicotine replacement therapy, while QuitGuide delivered smoking cessation content based on clinical guidelines. MAIN OUTCOMES AND MEASURES: The primary outcome was biochemically verified 7-day point prevalence abstinence at 26 weeks after quitting, and group differences were evaluated via multivariable logistic regression. Secondary outcomes included 30-day point prevalence abstinence and continuous abstinence. Outcomes were analyzed using logistic regression with intention-to-treat and complete-case approaches. RESULTS: A total of 454 participants (mean [SD] age, 52.0 [11.2] years; 333 [73.3%] female; mean [SD], 17.7 [9.5] cigarettes/d) were enrolled, with 225 randomized to Smart-T and 229 randomized to QuitGuide. Biochemically verified 7-day point prevalence abstinence at 26 weeks was higher in the Smart-T group than in the QuitGuide group (37 participants [16.4%] vs 23 participants [10.0%] in intention-to-treat analysis; 37 of 160 participants [23.1%] vs 23 of 161 participants [14.3%] in complete-case analysis). Adjusted odds of abstinence were significantly higher for Smart-T (adjusted odds ratio, 1.81; 95% CI, 1.03-3.18). No significant differences were found for 30-day or continuous abstinence. Smart-T users interacted with the app more often and rated it as more helpful (r = 0.21; P < .001). CONCLUSIONS AND RELEVANCE: In this randomized clinical trial of 454 adults with low income, the Smart-T intervention led to significantly higher smoking abstinence at 26 weeks compared with QuitGuide. These findings suggest that digital health interventions tailored for low-income populations hold promise for reducing smoking-related health disparities. TRIAL REGISTRATION: ClinicalTrials.gov Identifier: NCT03740490.