Hypertension is often described as a “silent killer” because it typically causes no symptoms while substantially increasing the risk of heart disease, stroke and other complications. Many people remain unaware they have elevated blood pressure, despite it being the leading modifiable risk factor for cardiovascular disease. Technologies that encourage earlier detection could therefore offer meaningful benefits.
In September 2025, the FDA authorised Apple’s Hypertension Notifications Feature for the Apple Watch, marking an important development in the use of wearable technology for cardiovascular health. The cuffless tool relies on optical sensors to analyse blood flow patterns and notify users when their data suggests possible high blood pressure. Although it is not designed to diagnose hypertension, the feature signals a broader move towards population-level screening using consumer devices.
The feature’s performance is far from perfect. Apple’s earlier validation work indicated that around 59% of people with undiagnosed hypertension would not receive an alert, meaning a high false-negative rate. Meanwhile, about 8% of individuals without hypertension would receive a false alert. Current clinical guidelines still require confirmation with both office-based and out-of-office cuff measurements, recognising that readings may differ between clinical and home settings.
To explore the potential public health impact of this technology, investigators from the University of Utah and the University of Pennsylvania conducted a modelling study, published in the Journal of the American Medical Association. The team assessed how widespread use of the feature might affect the likelihood that adults with no known diagnosis actually have hypertension, based on whether they receive an alert.
Using nationally representative survey data from U.S. adults, the researchers estimated how alerts might shift the probability of true hypertension across different demographic groups. The analysis focused on adults aged 22 years or older who were not pregnant and had no prior diagnosis of high blood pressure, mirroring the intended user population.
The results showed that the value of an alert depends heavily on baseline risk. Among adults under 30, whose overall prevalence of hypertension is relatively low, receiving an alert increased the probability of having hypertension from 14% to 47%. Not receiving an alert reduced the likelihood slightly, to 10%. For this younger group, the absence of a notification is therefore somewhat reassuring.
In contrast, among adults aged 60 and over, who already face higher rates of hypertension, an alert raised the probability from 45% to 81%, making it a strong indicator of disease. Yet the absence of an alert only reduced the likelihood to 34%, meaning many cases could still be missed. As prevalence rises, alerts become more predictive of true disease, while a lack of alerts becomes less reliable.
Similar patterns emerged across racial and ethnic groups. For non-Hispanic Black adults, an alert increased the probability of hypertension from 36% to 75%, while no alert lowered it only to 26%. Among Hispanic adults, the probability rose from 24% to 63% with an alert and fell to 17% without one. These differences mirror longstanding cardiovascular disparities shaped by social and economic determinants of health.
Given the scale of Apple Watch use, estimated at 30 million users in the United States and around 200 million globally, the researchers believe the feature could serve as a useful engagement tool. It may prompt individuals to seek medical evaluation who might otherwise remain unscreened. Nevertheless, they stress that it should complement, not replace, conventional cuff-based testing.
There is also concern that false reassurance could deter people from routine screening, particularly those who receive no alert despite being at higher risk. Current recommendations advise blood pressure checks every three to five years for adults under 40 without risk factors and annually for those aged 40 or older.
Clinicians are advised to follow up any smartwatch notification with high-quality cuff-based office measurements and, where appropriate, home or ambulatory monitoring to confirm a diagnosis. The research team plans further studies to estimate how many Americans would receive false positives or negatives and how these outcomes vary by region, income and education.
Overall, wearable technology shows promise as a screening aid, but it cannot yet substitute for established diagnostic methods.
Source: University of Utah Health
Image Credit: iStock
