Background: Coronary heart disease (CHD), the most prevalent type of cardiovascular disease among adults, has been identified as one of the chronic diseases which are epidemic in the world. Teaching and encouraging the working population to adopt a healthier lifestyle could favor in preventing and/or decreasing the incidence of CHD among this population. The use of mobile application (app) is the next logical wave of healthcare support tools to prevent and manage chronic diseases like CHD.

Aims: The aims of the study are to develop a mHealth programme, entitled "Care4Heart" for the working population in Singapore, and thereafter examine its feasibility and effectiveness in increasing the awareness and knowledge of coronary heart disease (CHD) as well as improving their heart-related lifestyle.

Methods: A two-phase study design will be adopted. Phase 1 is a pilot, two-arm randomized controlled trial (RCT) study and phase 2 is a single group pretest and repeated posttest longitudinal study. The study will be conducted in National University of Singapore. A convenience sampling will be used, and a total of 240 healthy working adults will be recruited via posters advertising in campus canteens, which comprising 80 participants in Phase 1 and 160 participants in Phase 2 study. The first recruited 80 participants will be randomly allocated to an intervention group and a control group, and only those in the intervention group will receive 4-week "Care4Heart" programme. For the participants recruited in phase 2 (n = 160), the newly developed mobile app will be installed onto their' smartphones, and a well-trained research assistant will brief the participants about the utilization of the app.

The main outcomes will be measured using the survey questionnaires: Awareness of CHD, Heart Disease Fact Questionnaire-2, Behavioral Risk Factor Surveillance System and Perceived Stress Scale. Data will be collected at baseline, and at the 4th week for phase 1 study while a third data collection at the 6th month thereafter will be conducted for phase 2 participants. Data will be analyzed using IBM SPSS 22.0.

Applications: If this project is proved to be feasible and effective, "Care4Heart" app, a novel CHD prevention programme will be popularized nationwide to promote knowledge and elicit positive heart-related behavioral changes for the working population in Singapore

The study aims to develop a mHealth programme, entitled "Care4Heart" for the working population in Singapore and examine its feasibility and effectiveness in increasing the awareness and knowledge of coronary heart disease (CHD) as well as improving their heart-related lifestyle.

The objectives are:

1. To develop a mHealth programme using the smartphone app, entitled "Care4Heart" for the working population in Singapore to assist them in establishing a healthy lifestyle.
2. To test the effectiveness of the "Care4Heart" app in increasing the awareness and knowledge of CHD among the working population in Singapore.
3. To test the effectiveness of the "Care4Heart" app in eliciting a positive heart-related lifestyle modification, including stress reduction among the working population in Singapore.

Background Deaths caused by CHD are often preventable. Deranged serum lipid profile, hypertension, obesity, physical inactivity and excess working stress are the well-known preventable risk factors of CHD, and the reduction of these risk factors will improve physical and psychological health and prevent future adverse and fatal cardiac events. Sedentary lifestyles and unhealthy diets are common reasons that may predispose Singaporeans to the risk of developing CHD, especially the majority of the workforce working in offices who engage in little or no physical activity. It was reported that about 40% of the working population (i.e. 21 to 65 years old) in Singapore do not engage in regular physical exercise. The increasing popularity of high fat diet and eating out and the high levels of stress experienced by the working population may further increase their risk of developing CHD.

Many of risk factors of CHD are modifiable and can be greatly reduced by adopting a healthy lifestyle. Exercising regularly and following a healthy diet plan are effective strategies in lowering cardiovascular risk factors. Obviously there is a need for an updated educational programme aimed at teaching and encouraging people in the working population to adopt a healthier lifestyle, which would result in them changing their behaviours and sustaining a healthy lifestyle to reach optimal health. Even though, health promotion programmes including the traditional face-to-face cardiac education sessions have been developed to be accessed by the general population, a known barrier for not reaching the working population is the lack of time as a result of long work hours. With a substantial increase in the number of people owning smartphones and a sharp increase in the usage of smartphones in recent years, the smartphone is a device most people in Singapore own. Recently the Infocomm Development Authority of Singapore (2013) announced plans for a well-connected mobile network to support major industries including healthcare. Hence the promotion of mobile health (mHealth) is the next logical wave of healthcare support tools to prevent and manage chronic diseases like CHD. A recent whitepaper based on market research conducted in Singapore reported that about 92% of Singaporeans aged between 25 to 39 years owned smartphones. While 83% of the older population aged from 55 years onwards owned smartphones as well. Based on this report, it is widely expected that mHealth will reach many Singaporeans as tools to maintain and improve their health.

Over the past few decades, more innovative ways for the design and delivery of primary/secondary prevention programme have been developed due to the rapid evolution of technology. One such programme used increasingly in the prevention and management of chronic diseases is mHealth which includes web-based programmes and smartphone applications (apps). Several studies conducted in Western countries reported on the effectiveness of mHealth in improving self-management skills and increasing healthy behaviours of individuals with chronic disease, such as diabetes, hypertensionand CHD. More importantly, apps are more accessible and convenient, enabling the information to reach more people by overcoming obstacles such as physical distance to attend a face-to face education session. However, these apps that have been developed are not completely relevant and suitable for Singaporeans because of significant cultural and economic differences that influence cardiac risk factors. For example the diet in Singapore and the culture of longer working hours are significantly different from Western countries.

Design/Methodology This study was funded by a grant from Singapore Heart Foundation (Grant Number: RG2013/02). A two-phase study design will be adopted. Phase 1 is a pilot, two-arm RCT study and phase 2 is a single group repeated test longitudinal study. The data of Phase1 study will be collected at the baseline and 4th week. The Phase 2 data will be collected at the baseline, 4th week and 6th months from the baseline.

Participants

The target population for this study is the working population in Singapore. The study will be conducted in National University of Singapore. A total of 240 convenient samples will be recruited via posters advertising in campus canteens, comprising 80 subjects in Phase 1 and 160 subjects in Phase 2 study. The first recruited 80 participants will be randomly allocated to an intervention group or a control group.

Phase 1 Randomization All eligible participants will be assigned a unique case number according to the sequence in which participants are recruited, for example, the first eligible participant will be assigned the number of one, and the second eligible assigned the number of two and so on. A total of 40 numbers without any duplicates will be randomly generated, from 1 to 80, using SPSS. Participants whose assigned numbers matched the numbers generated by the software will be allocated into the intervention group; otherwise, the participant will be assigned to the control group.

Theoretical rationale for intervention According to the Health Belief Model, there are several factors which influence health outcomes of an individual. These factors are: (1) the individual's belief that there is a threat to his/her health because of the illness, (2) the level of motivation of the individual to take action to improve his/her health and (3) the individual's belief that the intervention recommended will decrease the threat to his/her health. These factors will be addressed in our proposed "Care4Heart" mHealth programme which will cover the CHD risk factors, the possible health-threatening outcomes and strategies to decrease these risk factors are provided.

Intervention A 4-week mHealth programme in the form of a smartphone app, named "Care4Heart", has been developed. The content and scope of the design are developed by a thorough literature review and an extensive analysis of existing education leaflets and brochures used to prevent CHD. The contents are specified and tailored to the working population.

The app is developed by a team of software engineers from Computing School of NUS. Several functions include: (1) app using instructional video; (2) easy-to-read information on healthy lifestyle toward heart health, including information about the disease, CHD risk factors (e.g. diet, smoking cessation), stress, physical exercises and relaxation techniques; and (3) scheduled reminders for doing exercise and relaxation.

A website (www.care4heart.sg) has been created as well. Participants are allowed to visit the website for the details about this project and research team members.

Study procedure

Phase 1: Pilot RCT One face-to-face briefing session will be offered for the 40 participants allocated to the intervention group after the consent is obtained. The smartphone app will be installed to the participant's own smartphone, and one of the research team members will brief the participant on the utilization of app. This session will take about 20 to 30 minutes. After participants are familiar with the setup and the structure of the app, the participants will be expected to spend 15-20 minutes every day to go through all the educational content in 4 weeks' time. The participants will also be encouraged to change their lifestyle to modify their cardiac risk factors according to the information given in the app, for example engaging in regular exercise, and practicing relaxation.

No intervention will be provided to the participants in the control group. Data will be collected online. Participants can complete the questionnaires on the website (www.care4heart.sg). All data will be electronically stored in an encrypted and password accessed-only computer database, in accordance to the University's Research Data Management Policy.

The above questionnaires will be completed at two time points; (1) upon giving consent to participate in the study (baseline), and (2) at the 4th week.

Phase 2: single group pretest and repeated posttest longitudinal study A total of 160 participants will be recruited for phase 2 study. The same as phase 1 study, One face-to-face briefing session will be offered for all participants after the consent is obtained. The smartphone app will be installed to the participant's own smartphone, and one of the research team members will brief the participant on the utilization of app. This session will take about 20 to 30 minutes. . After participants are familiar with the setup and the structure of the app, the participants will be expected to spend 15-20 minutes every day to go through all the educational content in 4 weeks' time. The participants will also be encouraged to change the lifestyle to modify their cardiac risk factors according to the information given in the app, for example engaging in regular exercise, and practicing relaxation.

Data will be collected online. Participants can complete the questionnaires on the website (www.care4heart.sg). All data will be electronically stored in an encrypted and password accessed-only computer database, in accordance to the University's Research Data Management Policy.

The above questionnaires will be completed at three time points; (1) upon giving consent to participate in the study (baseline); (2) at the 4th week from the baseline; and. (3) at the 6th month follow-up period.

Data analysis All data obtained will be analyzed using IBM SPSS 22.0 (Armonk, NY, USA). Descriptive statistics, including the frequency distribution, mean and standard deviation will be used to describe the social-demographic and anthropometric data, HDFQ-2, BRFSS and PSS-10 of all participants. In Phase 1 study, significant differences in the change scores of HDFQ-2, BRFSS and PSS-10 will be examined via paired samples t-test and between-group changes will be examined via independent t-test. In Phase 2 study, significant differences in the change scores of HDFQ-2, BRFSS and PSS-10 will be examined via paired samples t-test. The level of significance selected for this study is set at p = 0.05, indicating a 5% of committing a Type I error. The Bonferroni posthoc test will be run to reduce the likelihood of identifying the difference by chance.

Inclusion Criteria:

1. working full-time;
2. aged between 21-65 years;
3. use a smartphone (e.g. Samsung, iPhone) in their daily lives frequently; and
4. able to read, speak and understand English.

Exclusion Criteria

1. have a clinical diagnosis of CHD or other heart diseases (e.g. congestive heart failure);
2. work in a health-relevant school/department/environment (e.g. school of medicine, school of public health, department of dentistry, school of pharmacy; university health centre); and
3. have reading difficulties.