A new study on the effectiveness of the Apple Watch and iPhone as a tool for measuring functional capacity in patients with cardiovascular disease (CVD) has been published by researchers at Stanford University.
The study, which involved 1
Weakness is measured in this case considering the distance a patient can travel in a six minute walk. This is normally tested with a six minute walk test (6MWT), and weakness was defined in the study “as walking
The study found that an Apple Watch was able to accurately assess weakness with a specificity of 85 percent and sensitivity of 90 percent in a supervised clinical test. But the potentially significant finding is that it was able to do the exact same thing with a specificity of 60 percent and sensitivity of 83 percent in unattended home tests.
The researchers therefore concluded that Watch is accurate enough to replace the clinic samples in many circumstances. Here is what the researchers’ article says about the test results:
Under a monitored clinic setting, the smartphone and Apple Watch with the VascTrac app could accurately assess “weakness” with a sensitivity of 90% and a specificity of 85%. Outside the clinic in an uncontrolled environment, the home-based 6MWT is 83% sensitive and 60% specific when it comes to assessing “frailty”. Passive data collected at home was almost as accurate in predicting weakness on a clinic-based 6MWT as a home-based 6MWT, with area under curve (AUC) of 0.643 and 0.704, respectively.
And here is their conclusion:
Although 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 deployment important. In this study, we showed that smart device-based measurements, including both 6MWT and passive aggregate activity data, provide clinically accurate and meaningful insights into functional capacity in patients with CVD.
You can read the entire paper on PLOS One. It is important to note that while the study was conducted independently, it was funded by Apple. The study also has a small sample size, and the sample size did not include much demographic diversity.
Apple may have funded the study to help with marketing or lobbying for the acceptance of an Apple Watch for this use case, or the company may have commissioned the study to print the results to inform decisions about which health features to invest in for Watch.
When the work for the study was done, researchers had to use an app called VascTrac to run the tests. But Apple has since added the 6MWT test as a built-in feature of watchOS, so an additional app will no longer be needed.
Apple CEO Tim Cook has said he sees portable devices like the Watch as the future of the company in many ways, and many of the advances in innovation and adoption the company has made in recent years have been in that category. Surveys like this help the company highlight that the products solve real problems.
That said, Apple’s claims on this front can not always pass. For example, some physicians have expressed concern that the watch’s attempts to identify atrial fibrillation do not adequately replace more robust tests, and that the measurements may lead to negative results for patients if they are misused.