App may let some hypertension patients skip doctor visits

Copied word for word from the study's registry entry, so the wording is the study team's rather than ours.

Inclusion Criteria: * (i) having a diagnosis of essential HT; * (ii) on anti-HT medications; * (iii) well-controlled HT on out-of-office BP measurements, including HBPM or ambulatory blood pressure measurements (ABPM) (measurement algorithm and details under methods). ABPM or HBPM are preferred to office BP due to their superior reproducibility and predictivity to cardiovascular outcomes. Furthermore, office BP misclassifies 30-40% of patients as having suboptimal BP control due to white-coat effect. From our pilot study, some patients with optimal BP are reluctant to undergo ABPM before recruitment into the RCT, and HBPM is more acceptable to these patients and is therefore included. According to local and international guidelines, optimal out-of-office daytime BP should be \<135/85 mmHg for patients without comorbidities and \<130/85 mmHg for patients with comorbidities that increase cardiovascular risk (i.e. stroke, ischaemic heart diseases, heart failure, diabetes mellitus (DM), and chronic kidney diseases) respectively; * (iv) can read basic Chinese (language used in the HealthCap); * (v) have used any mobile app (not HT-related) in the previous 1 year; and * (vii) aged between 18-80. Exclusion Criteria: * (i) cannot provide informed consent; * (ii) unwillingness to conduct HBPM or repeated ABPM; * (iii) relative contraindications to ABPM (i.e., diagnosed atrial fibrillation, nighttime workers, occupational drivers, or patients with bleeding tendencies); * (iv) have severe mental illnesses that impair their ability to use HealthCap, including those diagnosed with schizophrenia, dementia, or as being actively suicidal; * (v) a diagnosis of other acute or chronic diseases that need regular physical assessments and/or medication changes (e.g., suboptimally controlled DM \[e.g., glycosylated haemoglobin (HbA1c)≥7%\], depression requiring medications, active cancer); and (vi) predicted lifespan of \<1 year.