Step 1: design and development of the smartphone application ‘QinTB’

The design and development processes have three stages.

The first stage is to develop the conceptual and theoretical framework based on the TTM and PMT. TTM is a systematic theory of behaviour change that states that health behaviour is determined on a stage-to-stage basis.19 Applied to the ‘QinTB’ application, the behaviour of smoking cessation is divided into five stages: precontemplation, contemplation, preparation, action and maintenance. For any stage, the specific interventions will be provided through ‘QinTB’ to strengthen the behaviour change occurrence and/or support to achieve the next stage.

PMT is a systematic theory that states that intention, as the most significant predictor of behaviour, is determined by two processes: threat appraisal and coping appraisal. Threat appraisal is determined by an individual's beliefs about the negative consequences of the health threat (perceived severity), their vulnerability to the negative consequences of the threatened event (perceived susceptibility) and the benefits of the performance of the maladaptive behaviour (intrinsic and extrinsic rewards). Coping appraisal is determined by an individual's beliefs about the effectiveness of the preventative behaviour for the threatened event (response efficacy), confidence in one's ability to perform the preventative behaviour (self-efficacy) and barriers to performance of the preventative behaviour (response costs).20 21 Applied to ‘QinTB’, the behavioural intervention will be provided to enhance smokers’ perception of the severity of and their susceptibility to negative consequences and decrease smoking intrinsic and extrinsic rewards, aiming to increase threat appraisal. Moreover, a personalised intervention will be provided to enhance self-efficacy and decrease response costs, thus strengthening coping appraisal. The conceptual and theoretical framework for the ‘QinTB’ application based on the TTM and PMT is shown in figure 1, and the theories underlying the APP design are further described in table 1.

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Figure 1

Application structure and features. PMT, protection motivation theory; TB, tuberculosis; TTM,transtheoretical model.

In the second stage, we will hold several meetings. Experts in smoking cessation, health education, TB, etc, will join the meetings and will provide comments and suggestions for the ‘QinTB’ content. Then, the study team will revise those sections accordingly.

The last stage is to develop the ‘QinTB’ by using information technology. There are several important considerations. First, the application should ensure confidentiality of the data. Second, the system needs to be user-friendly with ease for quick data entry. Third, there needs to be a back-end server that stores the data for future analysis. Fourth, it should be usable and adaptable for common operating systems. Finally, the information must be presented in a way that is easily read and interpreted. Therefore, LimeJS, an HTML5 framework for touch screens and desktop browsers, will be chosen as the basis for the development of this application. The MySQL database will be used to track the smokers’ data and behaviours. On the server port, with multi-tier architecture, this application will divided into a display layer, a business layer and data layer to improve system reliability. In addition, in view of the possible high number of concurrent requests, container technology will be used to implement the rapid deployment strategy of multi-service instances and a streaming media player server will be established for video and audio playback to ensure fast response under the condition of high concurrent requests.

Step 2: prospective RCT to evaluate the APP-based smoking cessation intervention in TB patients

Inclusion criteria

1. Male, aged 18 to 60 years;

2. Diagnosed as active pulmonary TB based on WHO guidelines: including sputum smear-positive and smear-negative pulmonary TB patients;

3. Daily smokers, with ≥10 cigarettes smoked per day and ≥5 years of smoking duration (we require participants to be daily smokers to exclude smokers who are more likely to quit);

4. Expired air carbon monoxide ≥9 ppm;

5. Intention to quit smoking at precontemplation stage (not considering quitting in the next 6 months), contemplation stage (considering quitting in the next 6 months, but not in the next 30 days) and preparation stage (willingness to quit smoking within the next 30 days);

6. Own an iPhone;

7. Agree to participate and sign an informed consent form.

Exclusion criteria

1. Received any smoking cessation treatment within 30 days;

2. Diagnosis of HIV/AIDS or any mental diseases;

3. Unwilling to participate or unable to finish the study.

Randomisation

An independent statistician, Dr Huaqing Tan (Guanghua School of Management, Peking University) will oversee the randomisation but will not be involved in the treatment. With a randomised block design and the Fagerström test for nicotine dependence as a stratified factor, eligible participants will be assigned to one of two treatment groups: the APP group or the doctor’s advice group. The participants, research staff and physicians will not be blinded to the group allocation.

Baseline assessment

Research staff will conduct a face-to-face interview with recruited patients in their first visit. The interview will take approximately 30 to 45 min to complete, and answers will be input into a database by the staff. After completing the entire baseline assessment, participants will be given gift card valued at US$20. Following completion of this assessment, one of the two interventions will be delivered.

APP group

The participants in the APP group will be instructed to use ‘QinTB’ after randomisation. When first opening ‘QinTB’, participants will be welcomed, and they will be able to read information about the application. Next, participants will input their demographic information and complete an assessment. Then, smokers will be classified into the precontemplation stage, contemplation stage or preparation stage based on their intention to quit, according to TTM theory. For smokers who are at the precontemplation stage, the intervention that could enhance quitting motivation will be provided. For smokers who are at the contemplation stage or preparation stage, a 7 day window will be given to set their quit date. Once participants have set their quit date, they will be sent an automated message confirming their choice and recommending that they remain committed to their chosen date. From this point, they will be instructed to report their status every day, particularly their smoking status, TB medication compliance, etc. In the meantime, approximately three to five video and audio messages regarding the dangers of smoking in patients with TB, withdrawal symptoms and the management of cravings, avoiding potential cues and triggers and the benefits of engaging in a behavioural support programme, etc, will be sent per day. In addition, participants will be encouraged to actively read the information in the ‘QinTB’ application. All participants will be instructed to use this APP for 6 months.

Doctors’ advice group

The participants in the doctors’ advice group will receive doctors’ advice about smoking cessation from physicians at the Beijing Research Institute for Tuberculosis Control and Prevention. The doctor’s advice is based on the ABC intervention outlined in The Union’s Guide Smoking Cessation and Smoke free Environment for TB patients.22 In brief, it is a three-step cessation intervention method. The ‘A’ represents asking (ask patients if they currently smoke and if anyone smokes in their home), the ‘B’ represents brief advice (provide patients brief advice to quit smoking), the ‘C’ represents cessation support (provide patients cessation support to help them to quit and make their home smoke-free). The ABC intervention will be conducted each time patients attend face-to-face interviews with the research staff. The treatment duration for the doctors’ advice group is 6 months.

A Standard Protocol Items: Recommendations for Interventional Trials is presented in table 2.

Follow-up visit arrangement

All participants in the two groups will be instructed to attend face-to-face interviews with research staff 1 month, 2 months, 3 months, 4 months, 5 months, 6 months and 12 months after their quit date. In addition, to minimise the confounding effects of physician-patient communication, the interview in the APP group will be less than 10 min, and the words used during physician-patient communication will be more neutral. After completing the entire study, participants will be given another gift card valued at US$20.

Primary and secondary outcomes

The primary outcome is the 6 month sustained abstinence rate, defined as a self-report of smoking no more than five cigarettes from 2 weeks after the designated quit date, validated biochemically by an expired carbon monoxide level of less than 8 ppm at the 6 month follow-up and not contradicted by any previous self-report or validation result.23

Secondary outcomes are comprised of four aspects:

1. Health behaviour change:

   1. Perceived susceptibility, defined as vulnerability to negative consequences. Participants will be asked two questions, and they will report their agreement from 1 (strongly disagree) to 5 (strongly agree). Higher scores indicate greater perceived susceptibility.

   2. Perceived severity, defined as the seriousness of the negative consequences. Participants will be asked three questions, and they will report their agreement from 1 (strongly disagree) to 5 (strongly agree). Higher scores indicate greater perceived severity.

   3. Intrinsic and extrinsic rewards, defined as the benefits of the performance of a maladaptive behaviour. Participants will be asked three questions, and they will report their agreement from 1 (strongly disagree) to 5 (strongly agree). Higher scores indicate greater rewards.

   4. Self-efficacy, defined as confidence in one’s ability to successfully perform the preventative behaviour. Participants will be asked two questions, and they will report their agreement from 1 (strongly disagree) to 5 (strongly agree). Higher scores indicate greater self-efficacy.

   5. Response efficacy, defined as the negative consequences of the threatened event. Participants will be asked three questions, and they will report their agreement from 1 (strongly disagree) to 5 (strongly agree). Higher scores indicate greater response efficacy.

   6. Response costs, defined as the barriers to performance of the preventative behaviour. Participants will be asked three questions, and they will report their agreement from 1 (strongly disagree) to 5 (strongly agree). Higher scores indicate greater response costs.

2. TB treatment outcomes: treatment compliance, TB cure rate, loss to follow-up, treatment interruption and treatment outcome were not evaluated.

3. Utilisation of the APP: total time of APP utilisation, functions used and self-report preferences (eg, participants’ preferences for different components of the APP).

4. Whether an actual quit attempt lasting at least 24 hours was made.

Data management

Professor Xiao Li from the Chinese Center for Health Education will work with staff of the research team to maintain quality assurance for all data. The process will be checked according to the Standard Protocol Items: Recommendations for Interventional Trials. All the data will be stored and password-protected in the Beijing Research Institute for Tuberculosis Control. All patients’ information will be only accessible by personnel participating in the study. For the statistical analysis, all patients’ information will be encoded to guarantee that the personal information is unidentifiable during the processing of the data or the reporting of the results. The number of patients who drop out will be reported.

Sample size

The sample size calculation is based on a formula for comparing rates in two independent groups:

α is the probability of type I error (significance level) with a two-sided test threshold of 0.05; β is the probability of type II error (1-power of the test) with a one-sided test threshold of 0.2; P1 is the smoking quit rate in the group of patients undergoing doctors’ intervention, which was expected to be 35%; P2 is the smoking quit rate in the group with the mobile phone intervention, which is expected to be 50% and is the average rate of P1 and P2 provided that each group has and equal sample size. According to the formula, the sample size was calculated to be 170 for each group. After an attrition rate of 20% was taken into consideration, 200 were determined as the sample size for each group.

Statistical analysis

All data will be analysed using SPSS V.21.0. The level of bilateral significance for all statistical tests will be established at α=0.05.

The demographic characteristics, educational background, tobacco use information and smoking cessation stage according to the TTM at baseline will be compared between the two intervention groups using t-tests and Fisher’s exact tests.

Data will be analysed on an intention-to-treat (ITT) basis. In accordance with the ITT principle, all patients will be included in the analysis, independent of the groups to which they are randomly assigned and regardless of whether they complete the treatment. Participants who breach the protocol (taking cessation medication or receiving other cessation treatment) will be followed-up as part of their originally assigned group and classified according to their smoking status consistent with the other participants. Participants who are lost to follow-up or do not provide cessation outcome data will be classified as not being abstinent in the analysis.

Logistic and linear regression analyses will be used to compare the effects of two interventions on smoking cessation outcomes, the change of smoking-related health awareness and TB treatment outcomes. All the regression results will be presented as ORs with 95% CIs or the ratio of geometric means.

Ethics and dissemination

We will disseminate the findings of this study through peer-reviewed publications and conference presentations.

Patient and public involvement

This study had no patient involvement. Patients were not invited to comment on the study design and were not consulted to develop patient-relevant outcomes or interpret the results. They were also not invited to contribute to the writing or editing of this document for readability or accuracy.