In September 2025, the U.S. Food and Drug Administration cleared the Apple Watch Hypertension Notifications Feature, a cuffless tool that uses the watch's optical sensors to detect blood flow patterns and alert users when their data suggest possible hypertension. While the feature is not intended to diagnose high blood pressure, it represents a step toward wearable-based population screening.
In a new analysis led by investigators from the University of Utah and the University of Pennsylvania and published in the Journal of the American Medical Association, researchers examined what the real-world impact of this technology might look like if deployed broadly across the U.S. adult population.
"High blood pressure is what we call a silent killer," said Adam Bress, Pharm.D., M.S., senior author and researcher at the Spencer Fox Eccles School of Medicine at the University of Utah. "You can't feel it for the most part. You don't know you have it. It's asymptomatic, and it's the leading modifiable cause of heart disease."
How Smartwatches Detect-Or Miss-High Blood Pressure
Apple's previous validation study found that approximately 59% of individuals with undiagnosed hypertension would not receive an alert, while about 8% of those without hypertension would receive a false alert. Current guidelines recommend using both an office-based blood pressure measurement and an out-of-office blood pressure measurement using a cuffed device to confirm the diagnosis of hypertension. For many people, blood pressure can be different in a doctor's office compared to their home.
Using data from a nationally representative survey of U.S. adults, Bress and his colleagues estimated how Apple Watch hypertension alerts would change the probability that different populations of adults without a known diagnosis actually have hypertension. The analysis focused on adults aged 22 years or older who were not pregnant and were unaware of having high blood pressure-the population eligible to use the feature.
The analysis revealed important variations: among younger adults under 30, receiving an alert increases the probability of having hypertension from 14% (according to NHANES data) to 47%, while not receiving an alert lowers it to 10%. However, for adults 60 and older-a group with higher baseline hypertension rates-an alert increases the probability from 45% to 81%, while the absence of an alert only lowers it to 34%.
The key takeaway from these data is that as the prevalence of undiagnosed hypertension increases, the likelihood that an alert represents true hypertension also increases. In contrast, the absence of an alert becomes less reassuring as prevalence increases. For example, the absence of an alert is more reassuring in younger adults and substantially less reassuring in older adults and other higher-prevalence subgroups.
The study also found differences across racial and ethnic groups: among non-Hispanic Black adults, receiving an alert increases the probability of having hypertension from 36% to 75%, while not receiving an alert lowers it to 26%. However, for Hispanic adults, an alert increases the probability from 24% to 63%, while its absence lowers the probability to 17%. These differences reflect known disparities in cardiovascular health that are largely driven by social determinants of health, Bress said.
Should You Use Your Smartwatch's Hypertension Alert Feature?
With an estimated 30 million Apple Watch users in the U.S. and 200 million worldwide, the researchers emphasize that while the notification feature represents a promising public health tool, it should supplement-not replace-standard blood pressure screening with validated cuff-based devices.
"If it helps get people engaged with the health care system to diagnose and treat hypertension using cuff-based measurement methods, that's a good thing," Bress said.
Current guidelines recommend blood pressure screening every three to five years for adults under 40 and no additional risk factors, and annually for those 40 and older. The researchers caution that false reassurance from not receiving an alert could discourage some individuals from obtaining appropriate cuff-based screening, resulting in missed opportunities for early detection and treatment.
When patients present with an Apple Watch hypertension alert, Bress recommends clinicians perform "a high-quality cuff-based office blood pressure measurement and then consider an out-of-office blood pressure measurement, whether it's home blood pressure monitoring or ambulatory blood pressure monitoring to confirm the diagnosis."
The research team plans follow-up studies to estimate the actual numbers of U.S. adults who would receive false negatives and false positives, broken down by region, income, education, and other demographic factors.
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