The largest study ever of its kind enrolled over 400,000 participants from all 50 states in a span of only eight months.
The ResearchKit-based study launches in partnership with Stanford to identify irregular heart rhythms.
Six of the seven devices measured heart rate with an error rate of less than 5%, but none measured energy expenditure accurately.
The updated app includes the Stanford Coaching Module, which includes personalized coaching that varies for each user, depending on his or her activity profile.
The application is designed to work in the background to monitor user's communications to help track those that are at risk of committing suicide.
Using the app, patients can pay their medical bills, manage prescriptions, schedule appointments, and conduct video visits with Stanford physicians.
The wearable sensor can continuously collect and monitor users' sweat on the molecular level, and send them to a smartphone via Bluetooth.
Sponsored by NIH, the study will measure how specific social behavior, activities and exercises correlate with the body mass index (BMI).
The expansion to other markets was introduced as part of the update that added new features that help study participants keep their heart healthy.
However, some researchers caution about potential flaws in the information gathered through ResearchKit, while some others love it; FDA supports the efforts.