This study aims to examine the effectiveness and cost-effectiveness of WhatsApp group discussion for smoking relapse prevention. To assess the effect due to treatment modality through the WhatsApp social group, the frequency and topics of the posts in each social group will be analysed and in each participant. The primary hypothesis is whether quitters who participate in the WhatsApp group discussion will have a higher prevalence of validated tobacco abstinence at 12-month follow-up than those who do not. The second hypothesis is that greater participation in the social groups, indicated by number of posts received, posted and/or viewed, was associated with higher likelihood to quit at 12-month. The third hypothesis is that the WhatsApp intervention for a recent quitter is a more cost-effective option for tobacco abstinence and prolonged survival when compared to the control group.

Study design:

This is a 2-arm open-labelled pragmatic randomized controlled trial, by comparing the 12-month tobacco abstinence between the recent quitters who will join WhatsApp group discussion (Intervention group) and those who will not (Control group). A 1:1 randomised allocation will be used. The intervention content for both trial arms in the proposed trial will be the same and based on the US practice guidelines for smoking cessation, therefore the intervention effects due to the treatment content will be the same in both groups. Only the intervention platform (WhatsApp vs text messaging service) and the communication mode (one-way vs interactive) will be different between the 2 groups. This trial will be a pragmatic effectiveness trial to examine the effect of our intervention delivered under a real-life setting. A less stringent eligibility criteria will be applied for the subjects, unobtrusive measurement on adherence, and include all subjects in the final analysis regardless of intervention compliance of each subject.

Subjects:

Patients who are receiving the smoking cessation service in the smoking cessation clinic of the Queen Elizabeth Hospital, Tung Wah Groups of Hospital, Shau Kei Wan Jockey Club Outpatient Clinic, Sai Ying Pun Jockey Club Outpatient Clinic and Pok Oi Chinese medicine clinic. Smoking Cessation Service will be invited to go through the screening process. These clinics are under Hospital Authority (n=3), or are non-governmental organizations that are funded by the government (n=7). Patients with the following inclusion criteria will be invited to participate in the RCT and will proceed to the recruitment procedure and intervention phase (Phase 2).

1. Daily tobacco user before service intake
2. Aged 18 years or above
3. Have enrolled or re-enrolled in the smoking cessation treatment for no more than 8 weeks
4. Not using tobacco products (including traditional cigarettes and heat-not-burn tobacco products) for 3 to 30 days
5. Able to communicate in Cantonese/Mandarin and read Chinese
6. Have a smart phone with local network connection The 4th criterion will be used because our proposed RCT will target the quitters who have recently quit, and exclude those who will have maintained a longer period of abstinence.

Exclusion criteria:

• Do not use WhatsApp as communication tool and show no interest to use WhatsApp
• Have unstable physical or psychological conditions as advised by doctors or counsellor in charge
• Have become pregnant in the past 2 months If the smoker meet all eligibility except the abstinence (the 4th criterion), he/she will be introduced about our RCT and asked to sign a consent form that allowing the HKU research staff to contact him again for another screening in (Phase 1).

Procedures:

Recruitment:

During a usual smoking cessation counseling session, the clinic counsellor or onsite trial recruitment staff (TRS) will briefly introduce the importance of relapse prevention and our phone-based relapse prevention intervention to the patient. If the patient agree to join, the TRS will then assess the eligibility section on the consent form. Patients who meet all the eligibility criteria will (i) be introduced about the RCT that they will be randomized to either the intervention or control group, and will participate in all follow-up assessments; (ii) be asked to sign the consent form; (iii) fill in a baseline questionnaire; and (iv) receive a leaflet, a self-help booklet and a souvenir. The consented participant will proceed to the intervention phase (Phase 2) and will be informed group allocation (WhatsApp social group (Intervention group) or text messaging service (control group)), where the option of platform will be determined by a randomization procedure.

If participants meet all eligibility criteria in the first screening except the tobacco abstinence for 3 to 30 days, the recruitment staff will invite them to set a quit day and complete the above recruitment procedures, but not to be randomized at that time. TRS will contact the participant 3 days after the quit date, and re-assess the eligibility of the RCT. Then, the participant will complete a baseline questionnaire, and receive a leaflet, a self-help booklet and a souvenir which are the same as those given to patient who meet all criteria. These participants will proceed to Phase 1.

If the patient do not meet other eligibility criteria in the first screening, the TRS will only provide a booklet (which are the same as those given to recruited patient) to the patient. He/she will be regarded as recruitment failure.

Phase 1 (Telephone follow-up) The participants in Phase 1 will be contacted by TRS to confirm the abstinence status. If the participant has not smoked for 3 days, the individual will be asked again if he/she agrees to receive the phone-based relapse prevention intervention. If agree, the TRS will briefly introduce again the RCT, and complete a brief questionnaire on the telephone. Afterwards, the participant will proceed to the intervention phase (Phase 2). If the participant disagrees, TRS will ask if he/she likes to participate in the study. If the participant does not wish to participate in the study, then the individual consent form will be destroyed and will not be contacted.

If the participant has not quit smoking, the TRS will ask the participant to set a quit date again and ask his/her consent to be re-contacted for another telephone screening after the quit date. Patients who do not want to be re-contacted will be regarded as recruitment failure. Otherwise, the TRS will contact the participant again after the quit date.

Interventions (Phase 2) When the TRS (that has gone through training to be a WhatsApp group moderator) collects about 7 to 14 participants (who have met all eligibility criteria) every one or two weeks from all clinics, he/she will set up the WhatsApp group with them. Each WhatsApp group (about 50 groups in total) will allow real-time group discussion for 8 weeks. The participants will receive each week at least 3 text messages or videos from a moderator, which will be based on the six approaches delineated in "Treatments for the Recent Quitter" of the US Clinical Practice Guidelines on Treating Tobacco Use and Dependence. Based on the Positive Psychology theories, a framework of four principles to enhance the online group moderation: (1) Using active listening skills to understand the thoughts and feelings behind individual's sharing; (2) Showing sincere, immediate, specific, and concrete appreciation and gratitude towards their sharing; (3) Mindful awareness of the group dynamics and giving strategic reactions; (4) Enhancement of self-efficacy, sense of control and satisfaction among the individual. All messages will address the five common problems leading to smoking relapse delineated in "Treatments for the Recent Quitter" of the US Clinical Practice Guidelines on Treating Tobacco Use and Dependence (26), including (1) lack of support for cessation; (2) negative mood or depression; (3) strong prolonged withdrawal symptoms; (4) weight gain; and (5) smoking lapses. If any participant shares their lapse or relapse experience in the group, the moderator will engage other individual to provide appreciation and support, or, if that individual agreed, actively refer him/her to existing cessation services.

To ensure quality assurance and intervention fidelity, all moderators will be provided training of smoking cessation knowledge, and moderating skills to motivate individual to share in WhatsApp. Moderators will also be trained on Positive Psychology by psychologist and counsellors from United Christian Hospital, United Centre of Emotional Health and Positive Living. This would allow moderators to learn a more positive approach to the language use within the group discussion and ways to express gratitude. The control group will only receive 3 mobile phone text messages each week in the 8 weeks after recruitment. These messages will be similar to those received by the intervention group. Our intervention will not interrupt the services that all individual will be receiving in the cessation clinics.

Several measures will be used to protect the privacy of personal data and internet safety of joining the WhatsApp groups. First, male and female individual in the WhatsApp group will be separated into different WhatsApp groups to avoid the possibility of misconduct or harassment. Second, participants will be reassured that all the WhatsApp posts can only be read by the individual and the moderator in the group as stated in the consent form. The TRS will only analyse all the data and WhatsApp posts anonymously. Third, moderator will encourage all the participants in the WhatsApp groups to share and post messages in the group, and avoid 1-to-1 individual communication via any channels within the study period. The moderator will also encourage the individual to report if anyone violate this regulation, and, if so, may give warnings to that individual. If the participant severely violate this regulation, this may result in termination of their participation. The moderator will also monitor the group conversation and report any events of misusing the contact information in the WhatsApp to the lead PI. This can reduce the chance of any misconduct, harassment, sharing and spread of harmful programs or virus, and unauthorized marketing using the contact information. Fourth, to avoid any internet virus or harmful links, the moderators will remind the group members not to open any suspicious links and files via WhatsApp. Lastly, individual can withdraw from the intervention study anytime over the study period. In the pilot RCT, about 83.4% of the eligible individual agreed to participate in the WhatsApp social groups after informed the above ethical issues.

After the recruitment, TRS will immediately send the contact details of the participant to our research staff for the randomization procedures.

Randomization:

TRS will send the Information of all the participant to the research staff, who are responsible to randomly allocate the group assignment. The principal investigator will generate a list of random numbers (for each recruitment site) and a list of group allocation, using the rand function of Excel. TRS will assign group allocation to each participant based on the list, followed by the intervention delivery.

Allocation concealment:

All TRS and participants will be concealed to the group allocation at recruitment. This randomization procedure will be done by the research staff in the research office.

Blinding:

The participant and group moderators cannot and will not be blinded to the intervention. Assessors of the follow-up outcomes and the research analysts will not be involved in the recruitment and intervention delivery, and will be blinded to the group allocation (single blindness).

Follow-up:

All individuals will be followed up via telephone by an allocation-blinded interviewer at 3-, 6- and 12-month after the random group allocation. Only the individual who report abstinence in the past 7 days during the 6- and 12- month follow-up will be invited to provide samples of exhaled breath and/or saliva for biochemical validation at their residence, workplace, or nearby, as preferred by the quitters. The Bedfont Smokerlyzer and iScreen OFD Cotinine Saliva Test Kit will be used for validations. The validation takes very short time (3 minutes ) and is easy.

Sample size determination:

Our pilot RCT showed that the OR of the CO validated quit rates between the intervention and control group was 2.04 (95%CI 0.74-5.65) (Intervention: 26.0%, Control: 15.0%). Because our proposed RCT will recruit quitters who have recently quit, PI have conservatively estimated that the OR will be 1.70 (23.0% vs 15.0%). To detect a significant difference of quit rate with 2-tailed z-test by GPower 3.1 between the two groups with a power of 90% (to reduce type II error) and 5% significant level (type I error), 1,008 participantswill be needed in total (504 individual per group).

Data analyses

Statistical analysis:

Using intention-to-treat analysis, participants who are lost to follow-up or drop out will be treated as smokers with no changes in daily cigarette consumption. The odds ratio, risk difference, and 95% confidence interval will be used to compare the primary and secondary outcomes between the two trial groups. Number needed to treat (NNT), which shows the number of treated participants needed to have one additional quitter at 12-month, will be computed by taking the reciprocal of the risk difference between the two trial groups. Assuming the missing outcomes are dependent on observed data (missing at random), an analysis using the multiple imputation (MI) procedure to impute the missing data will be conducted as sensitivity analysis. On the assumption that there will be no heterogeneity of intervention effect across clinics, the primary analysis will be conducted using logistic regression with and without adjustment for baseline characteristics. The assumption of homogeneity will first be checked by testing the clinic by intervention interaction with clinic as a fixed effect in the logistic model. If there is evidence of heterogeneity (i.e. p-value < 0.1), an analysis by generalized linear mixed (GLM) model with clinic as a random effect will be used to summarize the intervention effect on the primary outcome. Number of posts received and posted by each participant will be documented, and then included in the final GLM model to assess their association with the cessation outcome. All data analysis will be done using IBM SPSS version 25.0.

Text mining of the WhatsApp groups:

All discussion content will be archived and anonymized to remove identifying personal information. Due to a huge number of messages from the 50 WhatsApp groups, an automatic, computational text mining and visualization of the dataset will be used for the content analysis. First, utilizing a lexicon of keywords derived from our qualitative analysis of the pilot RCT, a heatmap visualization will be developed to illustrate the prevalence of the discussion topics. Second, topic modelling will be applied to investigate emerging themes in our WhatsApp dataset, using the Mallet implementation of the Latent Dirichlet Allocation topic modelling algorithm. Topic modelling algorithms take as input a text dataset (in this case, the WhatsApp dataset), and output a set of topics (and their associated keywords) in addition to estimates of the proportion of each topic.

Qualitative interview

To collect opinions towards the WhatsApp group intervention, purposive sampling will be used to select 20 individuals from the intervention group including both sexes, all age groups and all smoking status at 12-month, to participate in a qualitative face-to-face or telephone interview after the intervention. An interview guide with open-ended and iterative questions was used to probe for more experiences from the interviewees. Each interview will be conducted by the PI and a trained research assistant, and will last about 30 to 60 minutes.

The interview content was transcribed verbatim in Chinese for further analysis. The qualitative interview transcripts will be analysed using framework analysis to construct a coherent and logical structure from the classification of many opinions and perceptions of social groups. Lead PI and two trained research assistants first used the open-coding method to identify relevant content in the transcripts; next, the lead PI will classified all labelled content into several independent themes showing distinct features of the social groups. The results were then discussed and consolidated in the panel meetings with the Co-I.

Cost-effectiveness analysis :

Cost-effectiveness analysis will be undertaken to indicate whether the intervention will be more cost-effective or even cost-saving option for a quitter over a time horizon of one year (within trial period) and lifetime. Within and lifetime cost-effectiveness analyses will be populated based on the healthcare provider perspective.

Model parameters input will be identified through within trial data and a review of local and overseas literature, where necessary. Within trial cost-effectiveness of WhatsApp intervention versus control group will be evaluated using total costs, the number of tobacco abstinence and total QALYs over the study period. EQ-5D-5L utility data at baseline and follow-ups from trial will estimate QALYs in two groups using area under the curve technique. Lifetime cost-effectiveness will be performed via Markov modelling that will simulate the annual health status progression of subjects in either intervention or control group. Both the successful and unsuccessful quitters after the trial will be subject to the annual transition probability from a status of no diseases to lung cancer, cardiovascular diseases, and other diseases, and then mortality. Former smokers may be relapsed after abstinence. Discounting will only be applied to total costs and QALY calculation under the lifetime horizon. Sensitivity analyses will be conducted where each parameter will be set at plausible lower and upper bounds based on 95% confidence interval of estimates in above data analysis.

The incremental cost-effectiveness ratio (ICER) in terms of cost per an additional tobacco abstinence gained, life-years gained, or QALYs gained for the intervention group in comparison to the control group will be reported. The WhatsApp intervention will be considered as cost-effective if its ICER will be less than 3 times per capita gross domestic product in Hong Kong recommended by WHO or the potential ICER threshold in Hong Kong. The cost-effectiveness model will be built using Microsoft Excel or Treeage Pro software.

Inclusion Criteria:

• Daily tobacco user before service intake
• Aged 18 years or above
• Have enrolled or re-enrolled in the smoking cessation treatment for no more than 8 weeks
• Not using tobacco products (including traditional cigarettes and heat-not-burn tobacco products) for 3 to 30 days
• Able to communicate in Cantonese/Mandarin and read Chinese
• Have a smart phone with local network connection

Exclusion Criteria:

• Do not use WhatsApp as communication tool and show no interest to use WhatsApp
• Have unstable physical or psychological conditions as advised by doctors or counsellor in charge
• Have become pregnant in the past 2 months

Research data and documentation will be available upon request.

3 years

12 months