Apple Watch Is Becoming Doctors’ Favorite Medical Device

Doctors are using the Apple Watch as part of how they diagnose and help their patients manage disease—whether or not it’s been specifically approved for such applications by the Food and Drug Administration or other regulatory bodies.

My own mother, who has a history of atrial fibrillation, a heart-rhythm disorder, is one such patient. The Apple Watch SE she bought on her doctor’s advice has been, by her account, a lifesaving intervention. It allows her to send data gathered by her watch directly to her doctor, as part of the continuing management of her lifestyle and medication.

There’s a large and growing body of research on how the Apple Watch is being used informally in medical care, despite other approved devices being available to track the same metrics.

“Not a week goes by in my clinic in which someone doesn’t come by and say, ‘My Apple Watch says I have an abnormal heart rhythm,’ ” says Dr. Rod Passman, a cardiologist and professor of medicine at Northwestern Medicine in Chicago.

Passman is currently conducting a six-year, National Institutes of Health-funded study, which includes 85 research centers across the country, as well as collaboration from Apple itself. The study is intended to determine whether data from the Apple Watch can be used in an app to significantly reduce the amount of time people with atrial fibrillation have to spend on blood-thinning medications. Currently, such patients must be on them all the time, even though they come with risks. The hope is that with an Apple Watch detecting if atrial fibrillation is actually occurring, patients will only have to take these drugs for 30 days after an episode has occurred.

To conduct this research, Passman and his colleagues applied for and received an exception to FDA rules that allows them to use the watch to alert patients who have already been diagnosed with atrial fibrillation that they are having an irregular heartbeat.

Meanwhile, many other doctors are telling their patients to go out and buy an Apple Watch to alert them to episodes of atrial fibrillation, despite the fact that the watch is not approved for performing this function in patients who already have a history of the disorder. (Apple Watch is FDA approved for alerting people with no history of atrial fibrillation that they are having an episode of it, but before you can turn on that function, you must answer “no” when the watch asks if you have a history of the issue.)

“From the FDA perspective, with few exceptions, healthcare professionals generally may choose to prescribe or use a legally marketed human drug or medical device for an unapproved or uncleared use when they judge that the unapproved use is medically appropriate for an individual patient,” says an FDA spokesman.

Doctors are opting for the Apple Watch because of the device’s simplicity, affordability, and ubiquity—Apple shipped about 40 million of its watches in 2023 alone, and even more in previous years.

Compliance is also an issue with medical-monitoring devices, and this is an area in which the consumer focus of the Apple Watch, which must appeal to as wide an array of people as possible, helps. One study of nearly 200 individuals found that they wore the watch four out of five days, for an average of more than 14 hours a day. That compares favorably with patient adherence to other treatments, such as medication and exercise, which is often a fraction of what doctors recommend.

All these factors have helped spark far-ranging research into using data from the watch in new ways. For example, researchers have shown the Apple Watch might be used to determine how stressed-out people are, track and improve recovery after surgery, and monitor the heart health of children.

Pedro Velmovitsky, who led the study on how the Apple Watch and other consumer health monitors can assess stress, says that such devices could eventually become the gold standard in how researchers study people’s stress levels, potentially leading to a variety of new public-health interventions intended to help treat stress for entire populations of people.

Importantly, in recent years none of the published research on new applications for the Apple Watch is coming from Apple itself. The company has faced a bumpy road in trying to make its watch a more capable device for monitoring health.

One problem has been the lack of accuracy of some of the sensors the company has contemplated adding to the device. Another is that, by entering the well-trod field of medical devices, Apple is inviting patent battles. Apple stopped selling some models of its watch last year due to a dispute with medical-technology company Masimo over blood-oxygen sensing.

So many off-label uses for the Apple Watch are already possible because the device continuously gathers activity and heart-rate data. It can perform an electrocardiogram when a user initiates that process. All this data can then be exported and analyzed without Apple or anyone else intervening.

Compared with previous methods of studying patients, the continuous monitoring made possible by the Apple Watch generates an avalanche of potentially useful data, says Dr. Corinna Zygourakis, a neurosurgeon who is conducting a study in how the watch can be used to monitor people after spinal surgery.

For Dr. Ruud Koster, a 72-year-old Apple Watch wearer living in Amsterdam, no such algorithm was required—because Koster has been a cardiologist for 50 years.

His experience shows what might be possible in the future, he says, if clinicians can apply to Apple Watch data new algorithms that possess the same pattern-matching skills he employed when, two years ago, he looked at an electrocardiogram from his Apple Watch after a workout at the gym.

Much to Koster’s surprise, the trace of that ECG on his watch indicated, in a single dip at the end, that he might be having a problem with his heart known as a silent ischemia. Feeling no discomfort or other symptoms, he continued to perform ECGs on himself using his watch over the following hour. The results indicated he should go to his doctor.

Soon after, he had bypass surgery to fix arteries in his heart that had become constricted. He wrote up the entire saga in a recent case report. Without his Apple Watch, he might not have discovered this life-threatening issue until it was too late, he says.

One major challenge of the potential flood of data from the Apple Watch is false positives. In a world in which tens of millions of wearables might be alerting people to potential health issues, record numbers of people might head for the hospital for unnecessary and expensive tests, says Koster. This is one reason regulators scrutinize medical devices before allowing their manufacturers to make specific claims about their abilities.

So far, the trial Passman is leading has been going on for 10 months, and his team has recruited 550 of the more than 5,000 people they aim to eventually enroll. Engineers at Apple are helping the team by giving them direct access to heart-rate data, something not typically available to developers who make apps for the watch and iPhone.

Apple has gone from one part-time doctor on staff, eight years ago, to having a whole team of cardiologists and heart-rhythm specialists on its payroll today, Passman says.

Indeed, in Apple’s report on its efforts in health, last updated in late 2023, Apple chief operating officer Jeff Williams wrote that the company’s goal “is to continue to create science-based technology that equips people with even more information and acts as an intelligent guardian for their health.”

At Apple’s recent developers’ conference, the company showed software changes coming in Watch OS 11, including an all-new “Vitals” app for more detailed health tracking.

Despite all of Apple’s efforts to make its watch better for health tracking, it’s clear that there’s a limit to what the company can and should do in terms of adding the kind of logic to the watch that might lead to more health alerts, says Passman. Apple’s role in his current study has been to give researchers the data, but after that, it’s up to the medical professionals to determine what to do with it.

“We are so inspired by the ways the research community is investigating the powerful sensors in Apple Watch to drive new scientific discoveries in their respective fields,” says Sumbul Desai, Apple’s vice president of health. “That’s why we invest in building tools and programs to help support their research efforts.”

If Apple can successfully navigate the minefield of finding new kinds of sensors that can perform as reliably as those already on the watch, without triggering new patent battles, the data from the watch could be used to diagnose and monitor all kinds of health conditions.

Taking the Apple Watch, and its competitors, to the next level as a health-monitoring device would require getting people to use it to perform more tests on themselves, and to share more of their data with systems that can automatically evaluate it.

Apple is unlikely to recommend that or enable it on its own, and it’s up to clinicians and researchers to figure out the appropriate medical use of tools like the watch, says Passman.

Write to Christopher Mims at [email protected]