This study is designed to assess the effect of implementing a mobile health (mHealth) strategy using text messaging for hypertension (HTN) management among hypertensive homeless persons with uncontrolled blood pressure age 21 or older in shelter-clinics in New York City (NYC). The study uses a randomized clinical trial design (homeless, n=120) and semi-structured interviews (homeless, n=30; providers, n=20).

The control group will receive text messages for usual standard care/healthy lifestyle during a 6-month follow-up period. The intervention group will receive text messages geared towards both standard care/healthy lifestyle and blood pressure control. At the end of study period, the investigators will assess changes in blood pressure (BP) measurements, adherence to clinic visits, and adherence to medication, and the investigators will compare them between the two groups. Qualitative interviews with both patients and providers who provide services to the homeless in shelter settings will develop a better understand barriers and opportunities regarding BP control. The investigators hypothesize that those individuals randomized to the intervention will experience a reduction in blood pressure (8mmHg systolic BP or diastolic BP) and will exhibit better adherence to blood pressure medications and appointments compared to the control group.

Project Renewal operates several urban shelters in five boroughs of NYC. Enrollment, data collection, and retention will be supported at these sites.

Patient participants will be recruited in clinics via medical record reviews and will be randomly assigned to treatment groups using a computer-assisted permuted randomization schedule with a block size of four, stratified by clinic site, severe mental illness, and active substance use disorder. Provider participants are physicians, nurse practitioners, social workers, and counselors working at Project Renewal.

The intervention will include 6 months of mHealth HTN management support via short message service (SMS) texts including reminders for medication adherence, appointment attendance, and HTN-specific health education and support. Texts will be delivered to support medication adherence and lifestyle changes, and participants will receive appointment reminders before each appointments. The control group will receive 6 months of mHealth including basic healthcare and general health promotion via SMS texts on the same schedule as the intervention group. Both groups will undergo BP measurements and adherence assessments at appointments in the shelter-clinics. All texts will be interactive and reciprocal; during the study, feedback to SMS texts, including automated and reciprocal feedback for patient-specific input, will be directly provided to patients to enhance education and behavioral changes.

Primary outcome measures will be recorded at 0, 2, 4, and 6 months, and secondary outcome measures will be collected throughout the study. Qualitative interviews with persons experiencing homelessness with HTN (n=30, 15 each arm) and providers (n=20) will be conducted at the end of the recruitment period. Trained research assistants (RA) will collect data and perform the semi-structured interviews.

During clinic visits, BP will be measured by trained clinic nurses in a seated upright position on the right arm with a properly sized cuff. Two readings will be taken at 2-minute intervals following 5 minutes of rest and will be averaged and recorded. Proportion of days covered (PDC) and pill counts will be conducted at each visit. Additional information, including appointment attendance, will be collected from the medical record.

Inclusion Criteria:

• Currently experiencing homelessness
• Current diagnosis of hypertension
• SBP above 140mmHg or DBP above 90mmHg at most recent clinic visit
• English or Spanish speaking
• Currently presenting to Project Renewal shelter-clinics for medical care
• Connected to multidisciplinary social and health services at Project Renewal

Exclusion Criteria:

• Pregnant or within 3 months post-partum
• Heart attack or stroke within previous 6 months
• History of aortic aneurysm
• Diagnosis of end-stage renal disease or currently on dialysis
• Inability to read or respond to SMS texts
• Any condition preventing participants from providing informed consent
• SBP >175mmHg or DBP >105mmHg unless medical provider determines patient has no symptoms suggesting a hypertensive emergency or urgency

Providers only participated in semi-structured interviews. No baseline or demographic data were collected for this group.

From enrollment to the completion of the Intervention period, up to 6 Months.

One participant died during the study period; this death was unrelated to the intervention.

We faced some challenges with enrollment due to post-pandemic constraints and the unexpected influx of newcomers into the shelter system in New York City, which were later resolved, and we added another enrollment site.