Table 1.

Definitions of concepts [39]

Concept	Definition
Health condition	A situation of impaired health
Health intervention	An activity performed by, for, with, or on behalf of a client(s) the purpose of which is to improve individual or population health, to alter or diagnose the course of a health condition, or to improve functioning
Core area	An aspect of health or a health condition that needs to be measured to appropriately assess the effects of a health intervention (core areas are broad concepts consisting of a number of more specific concepts called domains)
Domain or subdomain	Component of core area: a concept to be measured, a further specification of an aspect of health, categorized within a core area
Outcome	Any identified result in a (sub)domain arising from exposure to a causal factor or a health intervention
Measurement instrument	A tool to measure a quality or quantity of a variable, in this context a (sub)domain or a contextual factor
Outcome measurement instrument	A measurement instrument chosen to assess outcome(s)
Core domain set	For study of health interventions, the minimum set of domains and subdomains necessary to adequately cover all core areas (fully measure all relevant concepts of a specific health condition within a specified scope); it describes what to measure
Core outcome measurement set	The minimum set of outcome measurement instruments that must be administered in each intervention study of a certain health condition within a specified setting to adequately cover a corresponding core domain set; it describes how to measure
Scope	The set of factors that describes the studies and circumstances to which the core outcome set will apply. This is determined by the study questions and includes the health condition(s), target population, interventions, and so forth
Contextual factor	Variable that is not an outcome of the study, but needs to be recognized (and measured) to understand the study results. This includes potential confounders and effect modifiers