Apple’s Largest-Ever Health Study Could Be a Game-Changer
Aside from tracking your heart rate, workouts, steps, and more, the Apple Watch 4 now has a feature to notify you of irregular heartbeats-which are potentially dangerous because they could lead to strokes, blood clots, or heart failure.
To prove that this FDA-cleared technology is worth the hype, Apple partnered with Stanford Medicine on a research study on more than 400,000 people to identify irregular heart rhythms and potential atrial fibrillation (Afib) using Apple Watch data.
As part of the study, if an irregular heart rhythm was identified, participants received a notification on their Apple Watch and iPhone, a telehealth consultation with a doctor and an electrocardiogram (ECG) patch for additional monitoring. The findings were reported today at the American College of Cardiology meeting in New Orleans.
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How well did the watch work?
Given that the test was supported by Apple, it’s unsurprising that researchers found that the watch was effective in detecting heart rhythm disturbances. This feature has been criticized by some doctors because false positives could cause paranoia and create an uptick in unnecessary time and money spent visiting the doctor.
A very small percentage of participants received an irregular heart rhythm notification, illustrating the feature’s ability to give a user important health information without creating unnecessary burden to their doctor’s schedule. Many participants sought medical treatment following their irregular rhythm notification, using the information to have more meaningful conversations with their doctors.
In an exclusive interview on the eve of the publication of the study, Sumbul Desai, M.D., Apple’s vice president of health, said that during the conceptualizing and design of the product, Apple worked with the medical community-especially around the concern of how to ensure that it won’t drive unnecessary use of medical resources through false positives.
“Before a notification is given to a person, the feature has to see five instances that look like Afib,” Desai said. “By doing that gating within the algorithm, Apple designed toward specificity and toward avoiding unnecessary alerts.”
In the more than 400,000 participants, only 0.5 percent received a notification. “In people under 40 years of age, only 0.16 percent received a notification,” Desai said. “In those over age 65, the number was more frequent-just over 3 percent. This tracks with physicians’ understanding of Afib as being more common as you get older.”
Desai adds that Apple designed the Apple Watch 4 with the simple principle that the heart rate monitor feature and the ECG feature should be used in partnership with your physician to engage in a deeper conversation. “It’s not meant to diagnose or to officially screen,” she said. “It’s meant to be an initial data point for the individual, so they can take that information and have a more informed and thoughtful conversation with their doctor.”
Still, some cardiologists are also questioning how useful this information actually is. Christopher Kelly, M.D., cardiologist at Columbia University Medical Center, points out that there’s no clinical data from this trial showing that early Afib diagnoses make an impact.
“Just because you know about a disease earlier doesn’t prove that it’s a good thing,” Kelly said. He explains that treatment isn’t always possible for people who don't have stroke-related risk factors or experience symptoms from Afib, like shortness of breath.
However, Kelly maintains this technology is a step in the right direction. These findings could lead to clinical studies where doctors determine whether early detection helps people who are risk of Afib. “A successful screening test is not one that just detects something earlier-it detects it earlier at a time where earlier intervention improves outcomes,” he said. “Over time we’ll figure out how to best use this stuff.”
Powerful implications beyond the study
As much as this study was about Afib, it’s also about the convergence of digital technology and health.
“The Apple Watch is the most personal device ever,” Desai said. “When it’s with you all the time, it’s really an amazing opportunity, almost a responsibility to engage in your health and living a healthier life. As a doctor and as person, always want to be proactive about health, not reactive about care.”
Desai emphasizes that the heart study is only a first step. “With the watch, you have a platform that you can connect with a loved one, stay in contact with your family, understand how much you’re moving, but also potentially introduce features that will give you more meaningful information about your health,” Desai said. “What’s really powerful about that is when you bring in wellness-mindfulness, nutrition, exercise-plus these new personal health features, you’re creating something really powerful.”
From an advancement of science perspective the scale of the study “opens up a whole new road for evidence generation,” Desai said, which is an important step for digital technology. It’s the largest heart study ever to be done. (For comparison, the Framingham Heart study, probably the most famous heart study in history, initially had 5,209 participants.) “It shows Apple has the operational capability to do large-scale virtual trials.”
And finally, through the flow of the study, Apple learned other facts about participants’ health: 38 percent were obese based on body mass index, 21 percent had high blood pressure, 5 percent had diabetes, and 1 percent had a prior stroke.
“The population in the study had meaningful numbers of people with chronic disease and it pushes us to think about how we can help our customers become healthier,” Desai said. “Clearly, there’s an opportunity to get everyone more focused around health and being healthier.”
Apple is already working on new research, enrolling patients in a longer-term study with Johnson & Johnson, and investigating whether a new heart health program using an app from Johnson & Johnson in combination with the Apple Watch’s irregular rhythm notifications and ECG app can accelerate the diagnosis and improve health outcomes of the 33 million people worldwide living with Afib.
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