Cardiovascular Health and Text Messaging-Diabetes Mellitus (CHAT-DM) 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 with 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 percutaneous coronary intervention (PCI), have a history of diabetes mellitus, have the capability of reading and sending short message, and are able to provide informed consent. Patients will be excluded if they do not have an active mobile phone. 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 text messages for 6 months as well as usual care. They will receive one general messages, one hypertension message, one glucose control message, one lifestyle message, one medication adherence message and one physical activity message per week.

Outcome measures: The primary endpoint is the change in glycemic hemoglobin (HbA1C) as measured by central blood sample. Secondary endpoints include a change in proportion of patients achieving HbA1C<7%, body mass index (BMI), physical activity, medication adherence, systolic blood pressure, low-density lipoprotein cholesterol (LDL-C) and fasting blood glucose (FBG). Exploratory endpoints include long-term prognosis of the patients, such as death, nonfatal 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.

Inclusion criteria

• Participants with coronary artery disease defined as history of myocardial infarction and PCI
• History of diabetes
• Capability to read and send text messages

Exclusion criteria

• Assumed poor adherence
• Do not have an active mobile phone