Abstract Body: Background
Hypertension is leading risk factor for cardiovascular disease, which disproportionately affects racial and ethnic minority populations. These groups are often underrepresented in studies of hypertension prevention strategies due to persistent recruitment and engagement challenges including lack of trust in medical research. The LINKED-BP trial—a pragmatic, multi-level intervention combining home blood pressure telemonitoring and support from community health workers—was designed to address these disparities. Understanding how best to recruit these populations and demographic or clinical differences among those who do and do not enroll in hypertension prevention trials are essential to improving equitable participation.

Objectives
To evaluate which recruitment strategies were most effective and examine the demographic and clinical differences—including age, ethnicity, and gender—that distinguish individuals who were eligible but did not enroll from those who successfully enrolled in the LINKED-BP trial.

Methods
We conducted a cluster-randomized trial across 20 primary care practices in Maryland and Washington, DC. Eligible adults (ages 18–65 years) had elevated blood pressure (120–129/<80 mm Hg) or untreated stage 1 hypertension (130–139/80–89 mm Hg) without diabetes or cardiovascular disease. Using a HIPAA waiver, we identified potential participants via electronic records and recruited them through mailed letters, email, MyChart, calls, and SMS. We evaluated recruitment effectiveness by method of first contact and compared demographic characteristics of individuals who were eligible who did and did not enroll.

Results
We sent invitations to 921 potentially eligible participants, including 180 invitations via snail mail, 97 via email, 439 via SMS, 205 via MyChart. Of those, 704 were eligible, 499 consented, and 451 were enrolled. The outreach strategies with the highest recruitment yield were MyChart and email. Among participants who were eligible for the study, no significant differences in enrollment by age or gender. A higher proportion of those who did not enroll versus those who did enroll were Non-Hispanic Black individuals.

Conclusions
The most effective recruitment strategies were email and electronic patient portal (My Chart) outreach. However, demographic differences by race/ethnicity between enrolled and non-enrolled participants underscore the need for targeted strategies to ensure equity in hypertension prevention trial participation.