To assess the effectiveness of instant message-delivered personalised lifestyle modification (LSM) intervention for pre-hypertension (pre-HTN) management among community dwelling Chinese adults.

Systolic blood pressure (BP) of 120-139 or diastolic BP 80-89mmHg were previously described as 'high normal' or 'above-optimal', but have been re-defined as pre-hypertention (HTN) in the Seventh Report of the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure(JNC-7) in order to raise awareness regarding the risks of elevated BP and to emphasise healthcare professionals' roles in managing elevated blood pressures as part of primary HTN prevention. Prevalence of pre-HTN is significant, specifically reported as 36.4% of adults in a large-scale population study conducted in mainland China. Furthermore, evidence has shown that the incidence of clinical HTN over 4 years in people with pre-HTN is twice that of people with normal BP, of which approximately 17% had accelerated progression to more advanced stages of HTN. The data highlight that a significant proportion of populations at risk of developing HTN if pre-HTN remains undetected and unmanaged, and also the importance of screening for pre-HTN to initiate management and mitigate the risks associated with HTN.

Lifestyle modification (LSM) is the primary intervention for people with pre-HTN as they play a significant role in lowering BP without the use of pharmacological treatments. Both LSM interventions and pharmacological treatments have been recommended for people with HTN in clinical and public health guidelines. Ecological momentary intervention (EMI) is defined as a health intervention delivered though the mobile device's messaging functions, particularly instant messaging.In existing randomised controlled trials (RCTs), EMI also showed efficacy on LSM, including smoking cessation, diet control, psychological well-being, and weight loss. EMI can therefore serve as an important 'platform' to deliver the LSM intervention in a personalised, real-time and in-situ format.

Inclusion Criteria:

1. Systolic BP 120-139 or diastolic BP 80-89mmHg. The BP screening procedures and requirements (i.e., office BP measurement and ABPM) will strictly follow the International Society of Hypertension's Global Hypertension Practice Guidelines;
2. Aged ≥18 years;
3. Able to read and communicate in Chinese; and
4. Able to use mobile phone instant messaging function.

Exclusion Criteria:

1. Ever diagnosis of HTN;
2. Ever diagnosis of cardiovascular diseases (CVDs);
3. Pregnant or <3-month post-partum;
4. Current diagnosis of psychiatric disease or currently taking a psychotropic drug; and
5. Currently participating in any type of BP reduction intervention.