Brief Tobacco Cessation Intervention

Smokers will be recruited from the internal medicine outpatient clinics at the participating hospitals (the general nonprofit public hospitals) and community health centers. Same as the pilot study, trained doctors will ask all visiting patients during clinic consultation whether they smoke, confirm eligibility, provide information sheet and seek oral agreement to be followed up by telephone after clinic consultation. If eligible and oral consent obtained, the doctor will fill the recruitment form.

The doctors will randomly allocate the enrolled patient into intervention or control group using SNOSE method. This method will ensure allocation concealment. If the patient refuses to participate, the doctor will note on the summary form. Enrolled patients' medical records will be marked with a sticker (red for intervention group, green for control group) so they will not be recruited again if they come back to the participating hospital.

At the end of each clinic session, the doctors will immediately fill the rest part of the summary form and send the recruitment form and summary form to trained research assistants by email or WeChat. The research assistants will enter all information into a web-based or app-based study management system (SMS) using tablet PC.

For smokers in intervention group, the doctor will offer a brief (10-20 seconds) WAR smoking cessation intervention (Warn the smokers that at least one out of two smokers will be killed by smoking, and according to WHO, two out of three smokers will be killed by smoking; Advice the smokers to quit now or as soon as possible; and Refer the smokers to a smoking cessation clinic or telephone quitlines by offering a referral card which contains the contact information of the smoking cessation clinics and/or quitlines as well as a pictorial information leaflet which explains the risks of smoking). For control group, the doctor will offer a brief (10-20 seconds) placebo intervention (Advice the smokers to eat vegetables, and offer the smokers a card which contains information about the benefits of eating vegetables and a pictorial information leaflet which shows the recommended amount of vegetables and fruits an adult should eat a day).

Within 3 days after enrolment (T1), study personnel will call the participants using the tablet PC with questionnaire program to invite them to complete a short baseline survey.

At 1-month FU (T2), study personnel will call the participants using the tablet PC with questionnaire program to assess his/her smoking and quitting outcomes. After the assessment, trained study personnel will get the information about the participants' group status from the tablet PC. For Group C, the trained study personnel will end the phone call without further assessment or intervention. For Group I, the trained study personnel will use the tablet PC to randomly assign the participant to Group I-A or I-B.

For Group I-A, trained study personnel will repeat the brief (10-20 seconds) AWARD intervention (Warn the smokers that at least one out of two smokers will be killed by smoking, and according to WHO, two out of three smokers will be killed by smoking; Advice the smokers to quit now or as soon as possible; and Refer the smokers to a smoking cessation clinic or telephone quitlines by offering the contact information of the smoking cessation clinics and/or quitlines); for Group I-B, trained study personnel will end the phone call without further questions or actions.

At 3-month FU (T3), study personnel will use the programmed tablet PC to call participants and measure his/her smoking patterns and quitting efforts.

At 6- and 12-month FU (T4\&T5), study personnel will use the programmed tablet PC to call participants and measure his/her smoking patterns and quitting efforts again. Participants who report that they have been abstained from nicotine for ≥7 days will be invited to complete biochemical validation in clinics. Exhaled CO less than 4ppm and salivary cotinine less than 10ng/ml tested by NicAlert® strips (www.nymox.com) will be treated as validated abstinence. If for any reason, the participants are not able to complete the biochemical validation, study personnel will use the programmed tablet PC to conduct a non-biochemical validation survey to validate whether or not the participants have been abstained from nicotine.

Study personnel will always be blinded to participants' group status at follow-up interviews (single blinded). Subjects will be randomly allocated to study personnel for follow-up interviews, so subjects are likely to be interviewed by different study personnel in this study.

T-test will be conducted to compare the primary (a) outcomes and the secondary outcomes. Separate multivariate logistic regression model will be performed for each of the three groups (i.e., I-A, I-B, and C) between the baseline and the 12-month follow-up, controlling for age, gender, education, and income to determine whether the outcome of interests (quitting rate and smoking reduction rate) had increased, remained unchanged, or decreased. Change (e.g., increase or decrease) will be considered significant if p <.05.

Multivariate logistic regression models will also be used to examine if the smoking cessation intervention is associated with successful quitting and smoking reduction, as well as other factors (e.g., demographic variables) associated with successful quitting and smoking reduction.

Sensitivity test based on the result of physicians' fidelity check will be conducted to determine the effect of the physician's very brief smoking cessation counselling on quitting and smoking pattern changes. The fidelity check will evaluate the adherence of physicians' implementation to the study protocol.