Mobile Chat Messaging for Smoking Relapse Prevention

Importance Most individuals attempting smoking cessation relapse, even with evidence-based treatment. Mobile interventions offer a potential but largely untested strategy to sustain cessation. Objective To test the effectiveness of mobile chat messaging for relapse prevention among individuals who recently quit smoking. Design, Setting, and Participants This randomized clinical trial was conducted from March 14, 2023, to August 15, 2024, at 2 clinic-based smoking cessation services in Hong Kong. Participants were adults who smoked daily and had abstained for 3 to 30 days; they were randomly assigned to an intervention group or a control group. Interventions All participants received usual smoking cessation treatment from the services. The intervention group additionally received 3 months of mobile relapse prevention intervention, including chat-based support delivered by a live counselor and access to a supportive chatbot via a messaging app. The control group received 8 text messages on generic smoking cessation advice over 3 months as a contact control. Main Outcomes and Measures The primary outcome was biochemically validated tobacco abstinence at 6 months after randomization, defined by an exhaled carbon monoxide level of less than 5 ppm or a negative salivary cotinine test result. Secondary outcomes at 6 months included self-reported prolonged abstinence, 7-day point prevalence abstinence, and relapse (7 consecutive days of smoking) rate. Intention-to-treat analyses were conducted, assuming participants with missing outcomes relapsed. Results Of 590 participants, 465 (78.8%) were male, and the mean (SD) age was 47.1 (11.2) years; 294 were randomized to the intervention group and 296 were randomized to the control group. The retention rate at 6-month follow-up was 98.0% (n = 578). Biochemically validated abstinence at 6 months was significantly higher in the intervention group than in the control group (45.9% [135 of 294] vs 35.5% [105 of 296]; relative risk [RR], 1.29; 95% CI, 1.06-1.58; P = .01). The intervention group also reported significantly higher prolonged abstinence (57.5% [169 of 294] vs 47.6% [141 of 296]; RR, 1.21; 95% CI, 1.03-1.41; P = .02), higher 7-day point prevalence abstinence (65.6% [193 of 294] vs 54.7% [162 of 296]; RR, 1.20; 95% CI, 1.05-1.37; P = .007), and lower relapse rate (33.0% [97 of 294] vs 44.9% [133 of 296]; RR, 0.73; 95% CI, 0.60-0.90; P = .003) at 6 months. Conclusions and Relevance This randomized clinical trial found that mobile chat messaging for smoking relapse prevention increased validated abstinence by approximately 30%, offering a scalable approach to sustain abstinence among individuals who recently quit smoking. Trial Registration ClinicalTrials.gov Identifier: NCT05370352