Mobile Phone-Based Smoking-Cessation Intervention for Chronic Patients

Participants will receive three months of personalized chat support through WeChat. A total of 24 pre-set messages will be sent with the schedule of 3 times a week for 2 weeks, twice a week for the next 8 weeks and once a week for the last 2 weeks. These messages cover generic information about the benefits of quitting, methods to avoid/ manage craving or withdrawal symptoms, and hazards of smoking for chronic diseases experienced by different participants. Counsellors will respond to the participants' messages instantly. At the end of the initial phase (1-month), complete responders (quitters) will continue to receive PCS (subgroup PCS-1). Incomplete responders (smokers) will be randomly assigned to continue PCS (subgroup PCS-2) or receive PCS and MOS (subgroup PCS-3).

For incomplete responders (subgroup PCS-3) randomized to MOS, the available intervention options include phone counseling, family/peer support group and financial incentive for nicotine replacement therapy. Participants will be guided by cessation counsellors at 1-month follow-up to choose any combination of MOS based on their prefer choice or combination of MOS. If MOS participants cannot be followed up at 1-month, they will continue PCS by default.

Participant will receive three months of group chat support through WeChat. In this group, participants can send 'No Smoking' and the smart quit-smoking assistant will record it. A smoking cessation clinic doctor in the group will respond to participants' questions about smoking cessation. At the end of the initial phase (1-month), complete responders (quitters) will continue to receive GCS (subgroup GCS-1). Incomplete responders (smokers) will be randomly assigned to continue GCS (subgroup GCS-2) or receive GCS and PCS (subgroup GCS-3).

For incomplete responders (subgroup GCS-3) randomized to PCS, participants will receive the same intervention as Group PCS delivered at the initial stage. Participants will receive two months of personalized messages through WeChat. Please refer to Intervention Group 'Initial phase: Personalized Chat Support (PCS) for details.

5A's (Ask, Advise, Assess, Assist, Arrange) for smokers who are ready to quit, and 5R's (relevance, risks, rewards, roadblocks, and repetition) for smokers who are not ready to quit.

The contents of the leaflet include the absolute risk of smoking, diseases caused by active and second-hand smoking, horrible pictorial warnings of the health consequences of active and second-hand smoking, and the benefits of quitting.

The contents include information about the benefits of quitting, methods to quit, how to handle withdrawal symptoms, misperceptions of quitting, etc.