1. Process or activity of evaluating how well a medical service is provided. Now called quality improvement (QI) . This process may include formally reviewing health care given to a person or a group of persons, locating the problem, correcting the problem, and checking to see if the action taken worked or not. 2. Formal set of quality improvement organization (QIO) activities (formerly peer review organization [PRO]) designed to ensure the quality of medical services provided. See quality improvement (QI) .