AI health app shows promise in helping patients control blood pressure

At Rush University Medical Center, a straightforward question emerged from clinical frustration: if doctors knew how to treat high blood pressure, why did so few patients actually achieve control? The answer, it turned out, wasn't in the prescription pad. It was in the pocket.

A year-long study published in the Journal of General Internal Medicine tracked 425 patients with high blood pressure who incorporated a free smartphone app called Nuna into their treatment routine. The app, developed by Nuna, Inc., combined AI-driven coaching, daily blood pressure tracking, and behavioral nudges designed to reinforce healthy habits between clinic visits. Researchers compared their progress to a control group of 425 demographically similar patients receiving standard care alone. The difference was measurable and significant. Among patients whose blood pressure had crossed into uncontrolled stage 2 hypertension, those using the app saw their systolic readings drop by 13.6 millimeters of mercury. The control group, following conventional treatment, achieved a 9.0 millimeter drop. That gap—4.6 millimeters—may sound small until you understand what it means: established research shows reductions of this magnitude correlate directly with fewer heart attacks and strokes.

Hypertension is a problem of staggering scale in America. Nearly half of all adults meet diagnostic criteria for high blood pressure. The Centers for Disease Control and Prevention estimates that uncontrolled hypertension alone costs the healthcare system nearly $200 billion annually. Yet despite decades of effective medications and evidence-based treatment guidelines, fewer than 25 percent of adults with hypertension achieve adequate control. The gap between what medicine can do and what actually happens in patients' lives remains vast. Doctors see patients every few months, take a single blood pressure reading, and rely on memory and self-report. The rest of the time—the kitchen, the grocery store, the Tuesday night when someone is deciding whether to add salt—happens without clinical oversight.

The Nuna app was built to inhabit that gap. It sent daily reminders, tracked readings, offered personalized feedback, and used principles of behavioral economics to keep patients engaged. The retention numbers alone were striking: 87 percent of patients were still using the app at six months, and roughly three-quarters continued weekly use. In an industry where median app retention is less than 30 days, this was remarkable. Patients who used the app weekly had roughly 2.5 times the odds of achieving controlled blood pressure at six months compared to less frequent users.

What made the study compelling was not just the numbers but the voices behind them. Stanley R., a 74-year-old who had battled obesity and suffered a transient ischemic attack, described his relationship with the app in terms of friendship. "I'm in my 70s and really just used my cellphone to make calls," he recalled. "But then it helped me make monitoring my blood pressure a daily habit." The app's reminders guided him through the grocery store, teaching him which foods aligned with his care plan. "How could I ignore a friend like that?" he asked. Another patient, referred to as Daniel, a young man with extremely high blood pressure and other health challenges, reported that the app had coaxed him into daily walks and helped him give up salt. A third described gaining clarity about his condition: "I understand what my conditions are doing to my body, and how I can better control them."

Dr. Kristin Pallok, a Rush internal medicine specialist and study co-lead, framed the clinical significance plainly. The app gave physicians something they had never had before: a continuous window into patients' daily lives and progress, not a snapshot from a single visit. "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," she said. "Instead of lowering a patient's risk over a period of months, we can do it in weeks." The partnership between Rush and Nuna began when Nuna's CEO Jini Kim met with Dr. Omar Lateef, Rush's president and CEO, who described a familiar industry frustration: strong quality scores on paper but difficulty reaching blood pressure targets among historically hard-to-engage populations. Kim saw the problem clearly: physicians' reach ended at the clinic door.

Rush has since expanded the app to more than 1,700 patients managing hypertension, prediabetes, diabetes, and related cardiometabolic conditions. The scalability matters. Health systems cannot simply hire their way to better outcomes. An AI-based tool that extends a care team's reach to thousands of patients without proportionally increasing workload represents a different kind of solution—one that addresses not just the medical problem but the structural constraint of modern medicine. The Centers for Medicare and Medicaid Innovation have recognized this potential, recently releasing the ACCESS model to reimburse technology companies supporting chronic conditions, of which hypertension is one. Nuna, as a participant in this model, is positioned to help other health systems adopt similar approaches. Dr. Lateef reflected on the human dimension: early in the study, 20 percent of participants with uncontrolled hypertension brought it under control. "Twenty percent is a huge number in healthcare," he said. "If you take 20 patients with uncontrolled hypertension and make it controlled, you decrease strokes, and you decrease heart attacks, you cut the number of years robbed from people's lives. But as a physician and a community partner, we know these 20 people by name, we've met their families, and have been welcomed into their neighborhoods."