Key concepts used in the OMERACT Filter 2.0 Framework.
| Health | A state of complete physical, mental and social well-being and not merely the absence of disease or infirmity (WHO 1948) While this definition is widely accepted, it has a number of disadvantages. It is formulated in absolute terms and may be problematic to measure. Hence, Salomon, et al proposed33: “Health is comprised of states or conditions of functioning of the human body and mind.” It has been suggested that OMERACT forego defining health altogether and consider it to be a concept best described as “The resilience or capacity to cope and maintain and restore one’s integrity, equilibrium, and sense of well being” in 3 domains: physical, mental, and social34. The current WHO definition was endorsed by more people than the proposed alternative and is thus retained (84% vs 68%) |
| Health Condition | A situation of impaired health While a small minority objected to the term “health condition” replacing the word “disease,” this term was deemed best to accommodate conditions of disability where people have impaired function without active disease (e.g., someone with an amputated leg) |
| 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 The WHO International Classification of Health Interventions (ICHI) is still under development35. In particular the word “activity” remains controversial. After feedback we added the word “by” but otherwise included this definition |
| 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 We propose the term “Core Area” for the concept of “essential aspect of health.” i.e., the top-level categories of measurement. This word has been chosen as a neutral placeholder to avoid the definitional confusion that surrounds alternative phrasing |
| (Sub) Domain | A concept to be measured, a further specification of an aspect of health categorized within a Core Area “Domain” is used here for the concept describing the specification of a core area where measurement will need to take place (and measurement instruments need to be selected). Because of lack of consistency we initially suggested avoiding the word domain altogether and replace it with “dimension.” This alternative also proved problematic, and the consensus-based decision was to retain the term “Domain” |
| Outcome | Any identified result in a (sub) domain arising from exposure to a casual factor or a health intervention The initial proposal was: “Any identified result in health or a health condition, including those arising as a consequence of exposure to a causal factor or the handling of a (potential) health problem” “Outcome” and “trial endpoint” have been used interchangeably causing considerable confusion. Survey participants made many (often contradictory) suggestions, indicating the concepts were not clearly defined. The term “endpoint” is further complicated because it has been used to denote both outcomes and point in time. Within OMERACT, we have chosen not to use the word “endpoint,” and use the word “outcome” only in the context of the Core Outcome Measurement Set; we do not use the Term “Core Outcome Set” as there is currently no consensus on its technical definition |
| Measurement Instrument | A tool to measure a quality or quantity of a variable, in this context a (sub) domain or contextual factor The tool can be a single question, a questionnaire, a score obtained through physical examination, a laboratory measurement, a score obtained through observation of an image, etc. |
| Outcome Measurement Instrument | A measurement instrument chosen to assess Outcome The result of measurement (recently termed “specific metric”36) can be expressed as change, as end result, as cumulative result, or as “time to event” in a (sub) domain. Note that some instruments may measure more than one domain (e.g., indices combining the results of several instruments) |
| Core Domain Set | For studies of health interventions, the minimum set of Domains and Subdomains necessary to adequately cover all Core Areas, i.e., fully measure all relevant concepts of a specific health condition within a specified setting As elaborated below, the Core Domain Set defines the minimum requirements of what needs to be measured; the Core Outcome Measurement Set subsequently defines how to measure these Core Domains, i.e., the specific instruments required. The initial proposal was: “The minimum set of Domains and Subdomains necessary to adequately cover all Core Areas, i.e., fully describe all relevant concepts of a specific health condition in a specified Scope” |
| 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 specific setting to adequately cover a corresponding Core Domain Set The initial proposal was: “The minimum set of outcome measures that must be measured in each study of a certain health condition in a specified (set of) setting(s) to adequately cover a corresponding Core Domain Set” |
| Setting (scope): Contextual Factor | 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, etc. 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. The initial proposal was: “Variables related to the scope or setting of the study (and its core outcome set)” During discussions it became clear that context is critical in defining core outcome measurement sets. This is a very broad area in which various terms have been used to describe the different components. We prefer the broad term “contextual factor” as a placeholder for more specific words. Setting (scope) is usually determined by the study question and includes study population, interventions, etc. The contextual factors are not outcomes of the study, but need to be recognized (and measured) to understand and interpret the study results. Such factors include potential confounders and effect modifiers. In the ICF contextual factors have been described as environmental and personal factors that can influence the impact of the disease process on body functions and body structures, activities and participation |