A free AI-powered smartphone app helped patients lower their blood pressure by double-digit points when integrated into their doctor's care plan, according to a study published in the Journal of General Internal Medicine. The results point to a practical way for health systems to extend chronic disease management beyond clinic walls without adding to clinician workload-a persistent challenge as fewer than 25% of adults with hypertension achieve adequate control despite decades of treatment advances.
Researchers at Rush University Medical Center tracked 425 patients who used the Nuna app alongside their existing hypertension treatment and compared them to 425 demographically similar patients who received standard care alone. Over six months, app users saw greater systolic blood pressure reductions, with the most pronounced effect among those who started with uncontrolled stage 2 hypertension. That group dropped by an average of 13.6 mmHg, compared to 9.0 mmHg in the control group.
"The group that incorporated the Nuna app into their care showed clinically significant improvements," said Michael Gottlieb, MD, MBA, a Rush emergency medicine physician, vice chair of research, and the study's co-lead author. "While the study wasn't designed to assess hard clinical outcomes, established research has shown a direct correlation between reductions of this magnitude and lower rates of heart attacks and strokes."
What the app does and how patients used it
The Nuna app combines AI-driven health coaching, blood pressure monitoring, and behavioral incentives. Patients log readings and receive personalized reminders to maintain heart-healthy habits. Providers get a window into patients' daily routines between visits, rather than relying on a single in-clinic reading every few months. The app was built using behavioral economics principles, including gamification and AI-generated feedback tied to small daily actions.
Engagement held unusually well for a health app. At six months, 87% of patients were still using it, and roughly three-quarters continued to use it weekly. Weekly users had about 2.5 times the odds of achieving controlled blood pressure compared to less frequent users. "A care plan doesn't work in just a clinic," said Jini Kim, Nuna's CEO and co-founder. "It has to work in a kitchen, at a pharmacy counter, on a Tuesday night. We built Nuna to be there for those moments."
Patients described the app in relational terms. A 74-year-old user who started after a mini-stroke said, "Changing what I eat and buy at the store took time. But I would get daily reminders, and then I even learned to ask questions while at the store about which foods were right for me. It's with me…and how could I ignore a friend like that?" Another patient, a young man with extremely high blood pressure, told a Rush community health worker that "his new friend, Nuna" had coaxed him into daily walks and giving up salt.
Closing the gap between appointments
Kristin Pallok, MD, a Rush internal medicine specialist and the study's co-lead author, said the app addresses a shared frustration: physicians see patients every few months and must rely on a single day's reading and patient recall. "Nuna helps us understand what happens outside of the clinic walls. It's not a snapshot in time like a clinic visit, but rather a window into a patient's daily routine and blood control progress," she said. "We know long-term damage in cardiovascular disease is an accumulation of your risk over time, and now we can communicate more proactive treatment adjustments faster. Instead of lowering a patient's risk over a period of months, we can do it in weeks."
The partnership between Rush and Nuna started when Kim met Dr. Omar Lateef, President & CEO of Rush University System for Health. Lateef described a familiar problem: despite strong quality scores on blood pressure control, Rush struggled to reach historically difficult-to-engage patient populations. Kim said Nuna built the app to serve as "the visit between visits, translating the care plan into small daily actions." Nuna, Inc. did not fund the study or influence which statistical analyses were included.
Rush has since expanded use of the Nuna app to more than 1,700 patients for managing high blood pressure, prediabetes, diabetes, and related cardiometabolic comorbidities. The Centers for Medicare and Medicaid Innovation recently released the ACCESS model, which focuses on reimbursement for technology companies supporting chronic conditions including hypertension. Nuna participates in that model. The study authors suggest the Rush-Nuna collaboration can serve as a blueprint for scalable chronic disease management, an area where AI for Healthcare is drawing increasing attention from payers and health systems prioritizing value-based care.
Why this matters for healthcare professionals
For clinicians and health system administrators, the study offers evidence that a digital health tool can improve hypertension outcomes without proportionally increasing staff workload. The app did not replace clinical judgment-it plugged into existing workflows and gave providers visibility into what happens between visits. With the ACCESS model creating new reimbursement pathways for technology-enabled chronic condition support, health systems have a financial mechanism to scale tools like this. As Kim put it, "What we demonstrated at Rush is that an AI-based tool can extend a care team's reach to thousands of patients without proportionally adding to that team's burden." For healthcare organizations managing large panels of hypertensive patients, that capacity-to-outcome ratio is the metric that matters most.
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