The Smart Hypertension Control Study

The study team used structured language queries of electronic health record data from the Northwestern Medicine Enterprise Data Warehouse (NMEDW) to identify potentially-eligible participants with elevated blood pressure and exclude patients with clinical exclusion criteria from Northwestern Medical Group outpatient practices. During the on-site visit individuals were asked to provide written informed consent and have blood pressure measured in a standardized fashion to see if this inclusion criteria is met.

We conducted a non-blinded randomized controlled trial among hypertensive adults in NMG outpatient clinics. We randomized participants in a 1:1 fashion to the intervention group (HPCP + HBMD) or the comparator group (HBMD alone). Randomization was performed using a centralized computer-generated assignment sequence uploaded a priori to Northwestern University's REDCap (Research Electronic Data Capture) application. Randomization was stratified by: age (<65 or ≥65 years of age) and baseline systolic blood pressure (<145 or ≥145 mmHg) to optimize the likelihood of obtaining similar populations in each treatment group.

We recruited adults with elevated blood pressure as assessed by in-person standardized examination at baseline. We measured change in blood pressure by in-person examination at 6 months. We recruited between 350 to 400 participants in order to have 333 participants with analyzable data at the time of study completion. If changes were deemed necessary, a revision to the study protocol was submitted to the IRB for review and approval prior to implementing these changes.

Control group participants were provided with a home blood pressure monitoring device (HBMD) (Omron BP761N Bluetooth Smart Automatic Upper Arm Blood Pressure Monitor) and will be instructed in its use at the baseline study visit. Participant also received an information sheet describing home blood pressure monitoring that gives advice for how to respond to different home readings. At the baseline visit, participants were instructed to install an Omron application to their smart phone device (to monitor use of the HBMD). Participants continued to receive all routine care, including anti-hypertensive medications as prescribed by their regular clinicians.

The intervention group received all the interventions provided to the control group. Intervention group participants were sent a hyperlink to install the hypertension personal control program (HPCP) ("Lark HTN Pro"), which is a smartphone application installed on their iOS device during their initial office visit (screening/baseline) and successfully took a reading from their HBMD. The HPCP has blood pressure, medication, and weight monitoring, including periodic reminders for the user to measure blood pressure, measure weight, and take their medication(s). The HPCP provides real-time feedback based on user input, such as out-of-range measurements and has additional features designed to encourage behavior change in areas such as dietary intake, physical activity, sleep, and stress reduction.

Study participants were required to return for a 6-month study visit (within 2 weeks before to 4 weeks after). During the 6-month visit, subjects had their height/weight and blood pressure measured again. Participants also repeated questionnaires related to their current cardiovascular medications. They also completed questionnaires measuring: medication adherence, self-efficacy, diet, physical activity, and sleep duration. An exit survey was provided to participants at the end of the 6-month follow up visit to obtain feedback on Lark and Omron apps usability.

Inclusion criteria

• Adults aged 18 years to <85 years at the time of screening
• Standardized mean blood pressure measurement ≥135 to <180 mmHg systolic or ≥85 to <110 mmHg diastolic
• Have and use an iOS device(s) (iPhone generation 5s or newer)
• Able to provide written informed consent prior to participation in the study
• Receive their primary care from a Northwestern Medicine clinic site

Exclusion criteria

• Current user of the HCPC (Lark HTN Pro)
• Standardized mean blood pressure measurement ≥180 mmHg systolic or ≥110 mmHg diastolic
• Persistent atrial fibrillation as indicated in the electronic health record (EHR)
• Pregnant or planning to become pregnant during the study period
• Severe kidney disease, defined as estimated glomerular filtration rate <30 per 1.73 m2 or currently on renal replacement therapy (i.e. hemodialysis or peritoneal dialysis)
• Hearing impaired and unable to respond to phone calls
• Lack of fluency in English
• History of a cardiovascular event (stroke, transient ischemic attack, myocardial infarction, coronary artery bypass grafting) in the past 3 months
• Diagnosis of dementia as indicated in the electronic health record
• Diagnosis of psychosis as indicated in the electronic health record
• Terminal cancer diagnosis or NYHA III or IV heart failure
• Deemed unsuitable for study by primary care provider
• Individuals requiring BP monitor cuff size larger than 17 inches or 42cm