Apple says its smartwatch can identify high blood pressure. How legitimate is it?

Apple will soon launch a new smartwatch feature it says can help detect high blood pressure – but cardiologists are urging people to be cautious when interpreting the results.

Once the update is approved by regulators, the Apple Watch will use its light sensor to analyse how a wearer’s blood vessels respond to their heartbeat, alerting them if it detects consistent signs of chronic hypertension, or high blood pressure.

Notably, the watch will not offer actual blood pressure readings – just alerts that wearers may have hypertension. Apple said it will recommend that wearers who receive these alerts use a cuff to track their blood pressure levels over a week, and then contact their doctor with the results.

Health experts say that while the feature has some limitations, it could help raise awareness of a condition that often goes undetected.

Nearly 1.3 billion adults worldwide have high blood pressure, though nearly half do not know it. Most people don’t feel any symptoms, but hypertension raises the risk of heart attack, stroke, and kidney damage.

Apple said it expects regulators to approve the feature “soon,” and that it plans to roll it out in more than 150 countries and regions, including the European Union.

It will be available on its Apple Watch Series 9, and later, the Apple Watch Ultra 2 and watchOS 26.

The smartwatch feature could be “good for trends,” but should not be relied upon for precise health data or decision-making, Dr Felix Mahfoud, chair of the cardiology department at the University Hospital Basel in Switzerland, told Euronews Health.

“I can tell you what it means if we measure your blood pressure [in a doctor’s office], in terms of your risk of stroke” and other health issues, said Mahfoud, who is also communications chair for the European Society of Cardiology.

However, “all this is basically unknown for detection by smartwatches” and “no one should ever base any treatment or management decision based on a smartwatch,” he added.

In tests involving more than 2,200 people, Apple said the watch’s hypertension feature had a sensitivity rate – the ability to correctly identify a disease – of about 41 per cent, and a specificity rate – the ability to correctly identify the lack of a disease – of about 92 per cent.

That means the watch could miss more than half of hypertension cases, but it is not likely to issue many alerts for false positives.

Still, Apple said it expects to notify more than one million people with undiagnosed hypertension in the first year.

Whether the tool actually helps support patients' health will depend largely on whether doctors are willing to integrate the data into their own processes, said Kristof Vanfraechem, founder and chief executive of Data for Patients, which supports digital uptake by health care providers.

"Apple data has already been shown to be valuable; the key issue is how well health care systems are equipped to deal with it," Vanfraechem said in a statement to Euronews Health.

The feature also isn’t intended for everyone. The company does not recommend that people rely on the watch if they are under the age of 22, pregnant, or have been diagnosed with hypertension in the past.

Mahfoud said it could help make more people aware of the risks of high blood pressure.

“It’s great if we can increase awareness of hypertension, and hopefully these tools will do that,” Mahfoud said.

Updated 24 September: This article has been updated to include comment from Kristof Vanfraechem.