Table 1 Definitions of the terms used in this study protocol (Adapted from Boers et al .[17])

Health Condition

A situation of impaired health.

Health Intervention

An activity performed by, for, with, or on behalf of a client(s) whose purpose 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 casual 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.