Cardiovascular Health and Texting Messaging (CHAT) Study

Objective: This study aims to evaluate the effectiveness of automated mobile phone text message-based intervention for secondary prevention, including lifestyles modification, medication adherence improvement and risk factors control among CHD patients without diabetes. We hypothesized that an intervention using mobile phone text based education and reminder can improve risk factors control and medication adherence for CHD patients.

Study design: The study is a two-arm, parallel, randomized clinical trial. Patients will be eligible if they have documented CHD defined as having history of myocardial infarction and PCI but without diabetes mellitus, have the capability of reading and sending short message, and are able to provide informed consent. Patients who do not have an active mobile phone will be excluded. The eligible participants will be allocated into intervention and control groups in a 1:1 ratio randomly. The intervention group will receive intervention of pre-designed text messages in addition to usual care, while the control group will receive usual care. All the participants will be followed up for 6 months.

Study intervention: Participants in the intervention group will receive semi-personalized text messages for 6 months as well as usual care. Non-smokers will receive two general messages, two hypertension messages, one medication adherence message and one physical activity message per week. Smokers will receive one general message, two hypertension messages, one medication adherence message, one physical activity message and one smoking cessation message per week.

Outcome measures: The primary endpoint is systolic blood pressure control. Secondary endpoints include a change in proportion of patients achieving a systolic blood pressure<140mm Hg, physical activity, medication adherence, smoking cessation, low-density lipoprotein cholesterol (LDL-C) and body mass index (BMI). Exploratory endpoints include long-term prognosis of the patients, such as death, non-fatal myocardial infarction, stroke and so on, as well as health status (SAQ and EQ-5D).

Statistical analysis: Evaluation will be carried out on an intention-to-treat basis. Values of analyzed endpoints between intervention group and control group will be compared according to the analysis plan. We'll follow a prespecified analysis plan and subgroup analysis will be conducted accordingly.