Accepted for/Published in: Journal of Medical Internet Research
Date Submitted: May 29, 2025
Open Peer Review Period: May 29, 2025 - Jul 24, 2025
Date Accepted: Dec 10, 2025
(closed for review but you can still tweet)
Impact of Push Notifications on Physical Activity and Sodium Intake Amongst Patients with Hypertension: A Micro-Randomized Trial of a Just-In-Time Adaptive Intervention
ABSTRACT
Background:
Achieving adequate blood pressure (BP) control is challenging for patients and clinicians. Digital hypertension management solutions that utilize push notifications to promote lifestyle management have been proposed as an approach, but their effectiveness remains unknown.
Objective:
This analysis was designed to interrogate the independent and short-term effects of push notifications, tailored to participant and environmental factors, on physical activity levels and sodium intake amongst individuals with hypertension.
Methods:
The myBPmyLife study was a 6-month randomized-controlled trial of participants with self-reported hypertension recruited from an academic medical center and federally qualified health centers. A core component of the intervention consisted of micro-randomized push notifications promoting lifestyle modifications that were randomly delivered at four daily time points and focused on physical activity and dietary sodium intake. Our primary outcome was step count 60 minutes after a physical activity notification and lower sodium food choices 24 hours after a dietary notification. This analysis focuses on the results of the micro-randomized trial and used a centered and weighted least squares method adapted for two or more treatments.
Results:
298 participants were randomized to the intervention arm of whom 287 had data available for analysis. Participants’ mean age was 59.5 (SD 13.5) years, 137 (47.7%) were women, and 210 (73.2%) White. Participants were randomized at 187,517 time points over 6 months, which led to 0.96 (SD 0.86) push notifications/day divided between activity (50.4% [SD 0.4]) and dietary (49.8% [SD 0.4]) notifications. Activity notifications did not increase step count in the 60 minutes after a notification (Estimate 1.01, 95% CI 0.98 – 1.04; P = .40). Similarly, dietary notifications did not impact the number of lower sodium food choices in the subsequent 24 hours (Estimate 0.93, 95% CI 0.83 – 1.04; P = .23), but, in exploratory analyses, did increase mobile application use by 95.5% (95% CI 1.81 – 2.10; P < .001), mobile application clicks/searches by 93.4% (95% CI 1.72 – 2.16 %; P < .001), and low sodium searches by 113.0% (95% CI 1.73 – 2.53; P < .001), all within 60-minutes.
Conclusions:
In patients with hypertension, push notifications did not impact short-term physical activity levels or dietary sodium intake though did improve intervention engagement. Clinical Trial: ClinicalTrials.gov NCT05154929
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