Clinimetrics: the science of clinical measurements.

'Clinimetrics' is the term introduced by Alvan R. Feinstein in the early 1980s to indicate a domain concerned with indexes, rating scales and other expressions that are used to describe or measure symptoms, physical signs and other clinical phenomena. Clinimetrics has a set of rules that govern the structure of indexes, the choice of component variables, the evaluation of consistency, validity and responsiveness. This review illustrates how clinimetrics may help expanding the narrow range of information that is currently used in clinical science. It will focus on characteristics and types of clinimetric indexes and their current use. The clinimetric perspective provides an intellectual home for clinical judgment, whose implementation is likely to improve outcomes both in clinical research and practice.