Abstract 25: The Blood Pressure Effects of a Just-in-time-adaptive Intervention for Physical Activity and Diet in Patients with Hypertension: A Randomized Controlled Trial

Background: Emerging data suggest mobile health interventions are a promising approach for managing hypertension, but large-scale studies are lacking. The myBPmyLife mobile application is a just-in-time adaptive intervention incorporating behavioral change strategies such as goal setting, prompts, visualizations, and feedback to encourage increased physical activity and lower-sodium food choices. Methods: The study was a prospective, randomized-controlled trial that enrolled patients with hypertension from the University of Michigan Health in Ann Arbor, MI, and the Hamilton Community Health Network, a series of federally qualified health center clinics, in Flint, MI. Participants were randomized 1:1 to either the intervention group receiving the myBPmyLife mobile application or the control group and followed for 6 months. Participants in both groups received a smartwatch and a Bluetooth blood pressure (BP) monitor and were prompted to perform BP measurements once weekly. The primary outcome was systolic BP (SBP) change from baseline to 6 months. Secondary outcomes included change from baseline to 6 months in mean daily step count assessed by smartwatch and mean daily sodium intake assessed by the Block sodium screener. Results: The study enrolled 602 participants between December 2021 and July 2023. Mean age was 59.6 years (SD 14), with 74.4% self-identifying as White and 51.7% as men. Baseline estimated sodium intake was 3089 mg (SD 1078) per day, mean step count was 7618 (SD 3778) steps per day, SBP was 132 (SD 15) mmHg, and diastolic blood pressure (DBP) was 82 (SD 10) mmHg. Change in SBP from baseline to 6 months was -5.2 (SD 15) mmHg in the intervention and -5.7 (SD 15) mmHg in the control group (Table; p=0.76). Change in DBP from baseline to 6 months was -3.0 (SD 9) mmHg in the intervention and -3.6 (SD 10) mmHg in the control group (p=0.52). From baseline to 6 months, estimated daily sodium intake decreased by 1145 mg (SD 1023) in the intervention and 860 mg (SD 1001) in the control group (p=0.002), while mean daily step count increased by 170 steps (SD 2690) in the intervention and decreased by 319 steps (SD 2612) in the control group (p=0.040). Conclusion: A mobile health intervention, myBPmyLife, promoting lifestyle modification in hypertensive patients did not change SBP over 6 months compared to the control group despite significantly improving daily sodium intake and step count over that period.