Assessing the Feasibility of OptiBP Application for Home Blood Pressure Monitoring among Individuals with Hypertension in Rwanda

Background
Smartphone applications in healthcare are becoming popular and widespread across the globe. Most
of these applications screen, diagnose, and monitor health outcomes. The recent development of the
OptiBP application in measuring blood pressure is a ground-breaking technology that uses
smartphones already in the pockets of 3 out of 4 people across the globe (https://www.itu.int/itud/
reports/statistics/2022/11/24/ff22-mobile-phone-ownership/). The application uses
photoplethysmography (PPG) to analyse pulse oximetry and report blood pressure via the fingertip
(Schoettker et al., 2020). This study aimed to determine the feasibility of the OptiBP application for
self-monitoring blood pressure among adults living with hypertension in Rwanda. This study
employed the System Usability Scale (SUS), and the Unified Theory for Acceptance and Use of
Technology (UTAUT), to determine the usability and acceptance of OptiBP in Rwanda.

Methods
This cross-sectional study was conducted between May 12th and June 4th, 2023. The study focused
on individuals with hypertension. Participants were purposively selected from two public health
facilities, namely Nyarugenge District Hospital and Nyacyonga Health Centre, located in Kigali
City Province, Rwanda. The participants were provided with training on how to use the OptiBP
application. They were then instructed to measure their blood pressure at least twice daily for seven
consecutive days while using the application in their homes. At the end of the seven days, a
structured questionnaire was administered to assess the feasibility and acceptance of the OptiBP
application and analysis were performed quantitively. The questionnaire included sections covering
baseline information, the System Usability Scale, the Unified Theory for Use and Acceptance of
Technology.

Results
We enrolled 49 study participants to be involved in this study, however, 46.9% (n=23) were dropped
due to incompatibility of their smartphones with the OptiBP application after attempt to calibrate
their smartphones failed. The study found that 46.1% (n=12) of the participants considered the
OptiBP application usable, with a SUS score of ≥68 which is the ideal SUS score for a usable
application. Only length of smartphone use was found to have a significant association with SUS
scores (p-value = 0.048), indicating that more prolonged smartphone use was associated with higher
SUS scores and ease of use. Overall, participants expressed positive perceptions regarding the
possibilities and outcomes of the OptiBP application such as ease of use, ability to use the
application without help and willingness to pay a monthly subscription fee.
The Net Promoter Scale (NPS) analysis, which indicates the participants' willingness to recommend
the OptiBP application, shows no associations between sex, age, education, and length of
smartphone use. The compliance rates for blood pressure (BP) measurements show that 46.2% of
participants were compliant, while 53.8% were non-compliant. Being busy emerged as the primary
factor among the various reasons cited for non-compliance.

Conclusion
Several challenges related to smartphone compatibility, compliance, usability, and user concerns
need to be addressed for the broader implementation of the OptiBP application for self-monitoring.
The findings provide valuable insights for further optimizing the OptiBP application.