Wearable hypertension alerts aren’t meeting their promise, experts say

What if patients could learn their hypertension risk using a device they already own?

In a country where about half of adults have hypertension (chronic high blood pressure) but less than 10% get all their recommended screenings, this is an exciting idea. A 2023 study estimates that expanding home blood pressure monitoring could reduce heart attacks, strokes, and save an average of $7,794 in healthcare costs per person over 20 years.

Unfortunately, that promise hasn’t yet met its potential. It’s being held back by technological limits and a lack of clear guidelines and standards for consumer wearables, experts tell Healthcare Brew.

“Part of the problem is that we’re now entering this area where there’s this blurred line: Is this a medical device, or is it meant just for fun?” Jordana Cohen, associate professor of medicine and epidemiology at the University of Pennsylvania, told us.

Digging into data. Oura Health and Google are currently gathering data on detecting hypertension with their wearables, and the Apple Watch launched a hypertension alert feature in September.

The Apple Watch doesn’t directly measure blood pressure, however. Instead, an AI algorithm analyzes readings from the watch’s heart sensors and extrapolates, per Apple’s February 2025 application for FDA clearance. It’s been cleared by the FDA “to identify patterns that are suggestive of hypertension.”

The device flagged 41% of people with undiagnosed hypertension in a clinical study, but it missed 59% of them, according to a Feb. 9 JAMA analysis of data submitted by Apple to the FDA, coauthored by Cohen. In comparison, high-quality office blood pressure measurements correctly diagnosed 71% of people who were previously undiagnosed with hypertension, per a 2023 study.

Although the FDA reviews device performance data, it doesn’t require blood pressure devices to conduct standardized testing. Clearance does not necessarily mean a device is “accurate enough for clinical use,” per a December scientific statement from the American Heart Association (AHA) coauthored by Cohen.

While it’s “amazing” this watch may inform some people who wouldn’t have otherwise known they had high blood pressure, its results show it’s “not medical grade,” Cohen said.

Nonetheless, she’s encountered several patients who reply to their hypertension diagnosis with “Well, my watch didn’t alert me!”

Zooming out. To be fair, Apple’s website says not everyone with hypertension will get a notification. And the watch has been great at minimizing false positives. Only 8% of people without hypertension were falsely flagged as being at risk of hypertension, the JAMA study notes.

When it comes to hypertension, though, maximizing diagnoses is more important than minimizing false alerts, Cohen said. False diagnoses are problematic for things like cancer, where confirmatory checks can be costly for the healthcare system, but the worst case with an inaccurate hypertension diagnosis is a patient going in for a blood pressure check—something they’re supposed to do anyway, she said.

“It’s not a burden on the healthcare system to just have people appropriately coming in to get their blood pressure checked. Our goal is to get more people to do that,” Cohen said.

There’s more at risk if a patient were to bring in results to a doctor’s appointment from a wearable device and a doctor assumed they were using a more accurate at-home blood pressure monitoring device, Tammy Brady, director of hypertension and kidney health research at Washington, DC-based Children’s National Hospital and another coauthor on the AHA’s statement, told us over email.

“More and more, I am realizing that when patients come to me with blood pressure readings that are obtained outside of the clinical setting, it’s really important for me to ask them what device they used and how they obtained the measurements,” Brady said.