Frailty can be determined using a six-minute walking test (6MWT), and the metric is a general standard used to evaluate the functional mobility and exercise capacity of a patient. Higher scores indicate “healthier cardiac, respiratory, circulatory, and neuromuscular function,” according to Apple.
Conducted by Stanford University researchers and funded by Apple, the study provided 110 Veterans Affairs patients with cardiovascular disease with an iPhone 7 and Apple Watch Series 3. Patients conducted regular at-home six-minute walking tests, which were then compared to their standard in-clinic 6MWT performance.
The study found that an Apple Watch was able to accurately assess frailty with a sensitivity of 90 percent and specificity of 85 percent when supervised in a clinical setting. When assessed in an unsupervised setting at home, the Apple Watch was able to accurately assess frailty with a sensitivity of 83 percent and specificity of 60 percent.
The findings indicate that passive activity data gathered by the Apple Watch is an accurate predictor of in-clinic 6MWT performance.
In this longitudinal observational study, passive activity data acquired by an iPhone and Apple Watch were an accurate predictor of in-clinic 6MWT performance. This finding suggests that frailty and functional capacity could be monitored and evaluated remotely in patients with cardiovascular disease, enabling safer and higher resolution monitoring of patients.
While the study used a specially-developed app called “VascTrac” to gather 6MWT data alongside the Apple Watch’s passively-collected activity data, Apple has since included a series of new mobility-related health metrics in watchOS 7, including the 6MWT. It is likely that preliminary data from studies such as this encouraged Apple to add the metrics in watchOS 7.
The research may urge healthcare providers to offer at-home assessment of functional capacity in cardiovascular disease patients using an Apple Watch.