Performance outcome (PerfO)
A performance outcome (PerfO) is a type of clinical outcome assessment based on a standardised task actively performed by the patient according to instructions, and administered and evaluated by an appropriately trained individual or independently completed. Examples include the six-minute walk test, timed up-and-go, grip strength, the Nine-Hole Peg Test in multiple sclerosis, and cognitive tests such as the Digit Symbol Substitution Test or word recall tasks in Alzheimer's disease trials.
PerfOs measure what a patient can do rather than what they report or what a clinician judges, and are therefore valued for objectivity. Their limitations are learning effects, dependence on motivation and testing conditions, and the need for standardised administration. Digital versions, using smartphone sensors, wearables or gamified apps to record gait, speech, fine motor control or reaction time, are transforming PerfOs into continuous, home-based digital health technology measures, for which the FDA and EMA have issued qualification frameworks.
Digital PerfOs generate large volumes of raw sensor data, voice recordings and video, which are health data and may also constitute biometric data if processed to identify the individual. Voice and video are particularly hard to pseudonymise, algorithms deriving scores from raw data may be software as a medical device and high-risk AI systems, and continuous collection tests the minimisation principle. The DPIA should address raw-data retention, on-device processing options, vendor roles and the information given to participants about passive monitoring.
