Stanford University researchers have published a new study examining the effectiveness of the Apple Watch and iPhone as tools for measuring functional capacity in patients with cardiovascular disease (CVD).
The study, which involved 110 participants, found that the health monitoring capabilities in these products could complement or replace clinical testing for “vulnerability” in patients with CVD.
Vulnerability in this case is measured in terms of the distance a patient can travel in a six-minute walk. This is normally tested with a six minute (6MWT) walk test, and vulnerability was defined as “walking” in the study.
The study found that an Apple Watch could accurately assess vulnerability with 85 percent specificity and 90 percent sensitivity in a controlled, clinical trial. But the potentially significant finding is that it could accurately do the same with 60 percent specificity and 83 percent sensitivity in unsupervised, at-home tests.
The researchers therefore concluded that the Watch is accurate enough to replace clinical tests in many circumstances. Here’s what the researchers’ article says about the test results:
Under the supervision of the clinic, the smartphone and Apple Watch with the VascTrac app were able to accurately assess “vulnerability” with a sensitivity of 90% and a specificity of 85%. Outside of the clinic in an unsupervised environment, the home-based 6MWT is 83% sensitive and 60% specific in assessing ‘vulnerability’. Passive data collected at home was almost as accurate in predicting frailty on a clinical 6MWT as a home-based 6MWT, with area under the curve (AUC) of 0.643 and 0.704, respectively.
And here’s their conclusion:
While the benefits of telemedicine and remote monitoring – convenience, low cost, improved data quality – have been postulated for some time, the COVID-19 pandemic has made accelerated implementation a security imperative. In this study, we showed that smart device-based measurements, including both a 6MWT and passively collected activity data, provide clinically accurate and meaningful insights into functional capacity in patients with CVD.
You can read the full paper on PLOS One. It is important to note that although the research was conducted independently, it was funded by Apple. Also, the study has a small sample size and the sample size did not include much demographic diversity.
Apple may have funded the study to aid in marketing or lobbying for Apple Watch adoption for this use case, or the company may have commissioned the study to use the results to make decisions about which health features for the Watch must be invested.
Once the work on the study was done, researchers had to use an app called VascTrac to conduct the tests. But Apple has since added the 6MWT test as a built-in feature of watchOS, so an additional app would no longer be necessary.
Apple CEO Tim Cook has said he sees wearables like the Watch as the company’s future in many ways, and much of the progress the company has made in innovation and adoption in recent years fell into that category. Studies like these help the company prove that its products solve real problems.
That said, Apple’s claims in this area won’t always be condoned. For example, some physicians have expressed concern that the watch’s attempts to identify atrial fibrillation are not a sufficient substitute for more robust tests and that the measurements could lead to negative results for patients if used incorrectly.