Background: Hypertension is the leading attributable risk factor for cardiovascular disease and death globally. In diagnosing and monitoring hypertensive patient population, home blood pressure monitoring (HBPM) has been shown to be superior to the office-based blood pressure (BP) measurement as a predictor of cardiovascular disease and total mortality. However, the conventional method of HBPM utilizing handwritten BP logbooks has known shortcomings, mainly attributable to inaccuracy and underreporting of data, as well as the failure to bring the logbooks to the regular outpatient appointments. In recent years, the availability of home BP devices with Bluetooth® technology on the market, the increasingly widespread use of smartphones, and the development of mobile applications (apps) that complement Bluetooth® enabled BP monitors have expanded the potential for an accurate log of BP data to be accessible to clinicians. Our study's primary aim is to compare the level of HBPM recording fidelity using smartphone app versus using a handwritten logbook among the multi-ethnic hypertensive patient population seen in a district polyclinic located in Pasir Ris, Singapore. Patient acceptability of the two recording modalities and the association between the home blood pressure recording fidelity and the patients' socio-demographic background, self-care profile, clinical factors, and level of exposure to technology is also assessed as exploratory aims. Our main hypothesis is that the level of fidelity in HBPM recording, defined as the proportion of scheduled number of home blood pressure readings that is successfully recorded, regimen compliant, and made available at the final follow up visit, would be higher for patients who use a smartphone app versus those who maintain a handwritten logbook.

Methods/design: Open, randomized controlled trial of 80 patients seen at Pasir Ris Polyclinic randomized to either intervention or control arm and assessed after a 3-week follow up period

Intervention arm: Participants randomized to intervention arm follow a 3-week HBPM regimen and wirelessly record the BP readings onto a smartphone app using Bluetooth® technology.

Control arm: Participants randomized to control arm follow a 3-week HBPM regimen (identical to intervention arm) and manually record the BP readings onto a handwritten logbook.

Participants: A convenience sample of 80 patients visiting the study polyclinic was obtained during the recruitment period (15 Mar 2017 - 15 June 2017).

Outcomes: A trained outcomes assessor will assess each participant's home BP record brought to the final follow up visit at 3 weeks post-randomization. The primary outcome will be HBPM recording fidelity, defined as the proportion of scheduled number of home blood pressure readings that is successfully recorded, regimen compliant, and made available at the final follow up visit. The participants' level of discomfort during the study, their willingness to incorporate into their healthcare management the modality of HBPM to which they were assigned, and their overall impression on their study participation will be assessed by a participant acceptability questionnaire.

Inclusion Criteria:

• Singaporean citizen or permanent resident
• Able to communicate in English
• Diagnosis of essential hypertension and on at least one antihypertensive medical therapy
• Between 40-70 years of age
• Owns a smartphone compatible with the study
• Has been visiting the study polyclinic for at least 1 year

Exclusion Criteria:

• Known cardiac arrhythmia
• Known end stage renal disease
• Known cancer patient
• Known history of stroke
• Known history of myocardial infarct
• Physical or mental disability that would prevent one's own measurement of home BP (e.g. visual impairment, dementia)
• Maximal arm circumference exceeding BP cuff size
• Anticipation of extensive travel overseas during study period
• Occupation requires night shift
• Participating in other clinical trials