CDISC-Gloss – A PerfO is a measurement based on a task(s) performed by a patient according to instructions that is administered by a health care professional. NOTE: Performance outcomes require patient cooperation and motivation. These include measures of gait speed (e.g., timed 25-foot walk test), memory recall, or other cognitive testing (e.g., digit symbol substitution test). [After 1. FDA Clinical Outcome Assessment (COA) Glossary; 2. After BEST Resource]