Participants
RECRUITMENT, LOCAL DISEASE
The sample size calculation for the study was based on the formula for a two-arm randomized controlled trial. Based on earlier research, we estimated that biochemically verified continuous smoking abstinence at 6 months would be approximately 4% in the control group and 10% in the intervention groups.We advertised the trial to smokers through leaflets, digital advertisements on WeChat and via teachers and community leaders. Potential participants contacted the local disease control and prevention centre to register. Daily or weekly smokers aged 18 years or older were eligible for inclusion if they owned a mobile phone and used the WeChat application. All eligible smokers were told they needed to come to a specific place on a fixed date to finalize the recruitment process. The eligibility of participants was double-checked by the research team or local centre staff, and participants signed an informed consent form at the first face-to-face contact.