The use of digital health technologies (such as smartphones, tablet computers, and portable, implantable, or wearable medical devices) present a wide array of challenges and opportunities for medical research. There is much to be learned about how well these devices work, their validity and reliability. While these devices hold abundant promise, they are imperfect measures and are not commonly used in clinical trials (Clinical Trials Transformation Initiative 2016). For example, if a participant is wearing an activity monitor and claps at a concert, it is possible that the device could record this as running? Or, will a geo-spatial device record running on a treadmill as activity at all?

Some examples of the utility of these devices include:

• A PCT can be designed where a patient has an application (app) for their phone that provides passive or active surveillance. For example, an app with geo-sensing can ping a person who enters the hospital with the question: Why are you in the hospital? Or Are you ill?
• The Personalized Patient Data and Behavioral Nudges to Improve Adherence to Chronic Cardiovascular Medications (Nudge) trial used mobile phone technology to remind patients about medication adherence.
• Some devices will transmit data about a participant’s health status to a data warehouse every night. The devices can measure physiologic functions, such as how active a person is, heart rate, etc. As a hypothetical example in a PCT designed to evaluate how to prevent cardiac death, a patient could wear a heart monitor that detects arrhythmias and other heartbeat abnormalities, as well as whether or not a patient is hospitalized.
• Patients with type 1 diabetes can use continuous glucose monitors (CGMs) to monitor their blood glucose levels, and this information can be sent to a smartphone, and CGM-specific receiver, or an insulin pump (Clinical Trials Transformation Initiative 2016).

Digital health technologies can be part of a decentralized clinical trial, in which some or all study-related activities occur at a location separate from the investigators location. As described in the Living Textbook Chapter on Decentralized Clinical Trials, a critical consideration when using digital health technology is quality assurance: one must ensure that the right patient receives the right treatment and provides the right data. For example, if the mobile health technology is a pedometer, one must ensure that others in the household do not wear it.

For more on digital health technologies, see FDA’s Digital Health Technologies for Drug Development.