In an effort to address differing definitions of the term “digital biomarker” and improve discussions on drug and device development, FDA officials have penned an article meant to clear up misconceptions and spur alignment toward the agency-endorsed definition.

In the eyes of the FDA, a digital biomarker is “a characteristic or set of characteristics, collected from digital health technologies, that is measured as an indicator of normal biological processes, pathogenic processes, or responses to an exposure or intervention, including therapeutic interventions,” according to the paper, which was published March 25 in npj Digital Medicine.

Despite the agency’s official position on a definition, multiple definitions are being seen in scientific literature, some of which appear to confuse established definitions of biomarkers with clinical outcome assessments (COA), the authors wrote. This conflation of terms, they cautioned, may lead to disconnects in communications and data expectations between companies and regulatory agencies.

“Our objectives are to align the meaning of ‘digital biomarker’ with established biomarker terminology and to highlight opportunities to enable consistency in evidence generation and evaluation, improving the assessment of scientific evidence for future digital biomarkers,” they wrote.

The paper includes two tables designed to help understand the differences between digital biomarkers and other kinds of assessments.

For instance, the authors pulled digital biomarker examples from published literature for a diagnostic biomarker, a pharmacodynamic/response biomarker and a monitoring biomarker and compared them to the FDA/NIH’s Biomarkers, Endpoints and other Tools (BEST) definitions:

• Example of diagnostic biomarker: An algorithmic classification of cardiovascular features extracted from optical sensors on wearable devices to identify atrial fibrillation.
  The BEST definition: A biomarker used to detect or confirm the presence of a disease or condition of interest or to identify individuals with a subtype of the disease.
• Example of pharmacodynamics/response biomarker: A wrist-worn digital health technology that may collect accelerometer data and use the data to detect physiological changes (for e.g., tremor and bradykinesia) in response to a pharmacological agent.
  The BEST definition: A biomarker used to show that a biological response has occurred in an individual who has been exposed to a medical product or an environmental agent.
• Example of monitoring biomarker: An accelerometer-based sensor device that collects data about chest and limb movement to measure gait in patients with Huntington’s Disease.
  The BEST definition: A biomarker measured repeatedly for assessing the status of a disease or medical condition or for evidence of exposure to (or effect of) a medical product or an environmental agent.

The second table distinguishes a theoretical digital biomarker designed to evaluate hand function using a smart phone from various COAs.

For example, while the digital biomarker tasks a trial participant with completing a tapping exercise on the device to measure the location of the tap/delays between taps and identify an early sign of a neurological disorder, the COA instructs participants to do a tapping exercise on the device to measure their functional ability.

“While it is clear that the continued development, access and adoption of digital biomarkers depend on the entire healthcare ecosystem working together, consistent use of the definition of digital biomarker described here will help improve communication critical for medical product development,” the authors concluded.

Read the full paper here: https://go.nature.com/3DnhHSB.