Workshop on Improving Disability Data for Policy
|Documentation for the Workshop /
Basic Documents : the ICF
ICF: The International Classification of Functioning, Disability and Health
This volume contains the International Classification of Functioning, Disability and Health, known as ICF.  The overall aim of the ICF classification is to provide a unified and standard language and framework for the description of health and health-related states. It defines components of health and some health-related components of well-being (such as education and labour). The domains contained in ICF can, therefore, be seen as health domains and health-related domains. These domains are described from the perspective of the body, the individual and society in two basic lists: (1) Body Functions and Structures; and (2) Activities and Participation.  As a classification, ICF systematically groups different domains  for a person in a given health condition (e.g. what a person with a disease or disorder does do or can do). Functioning is an umbrella term encompassing all body functions, activities and participation; similarly, disability serves as an umbrella term for impairments, activity limitations or participation restrictions. ICF also lists environmental factors that interact with all these constructs. In this way, it enables the user to record useful profiles of individuals' functioning, disability and health in various domains.
ICF belongs to the "family" of international classifications developed by the World Health Organization (WHO) for application to various aspects of health. The WHO family of international classifications provides a framework to code a wide range of information about health (e.g. diagnosis, functioning and disability, reasons for contact with health services) and uses a standardized common language permitting communication about health and health care across the world in various disciplines and sciences.
In WHO's international classifications, health conditions (diseases, disorders, injuries, etc.) are classified primarily in ICD-10 (shorthand for the International Classification of Diseases, Tenth Revision),  which provides an etiological framework. Functioning and disability associated with health conditions are classified in ICF. ICD-10 and ICF are therefore complementary,  and users are encouraged to utilize these two members of the WHO family of international classifications together. ICD-10 provides a "diagnosis" of diseases, disorders or other health conditions, and this information is enriched by the additional information given by ICF on functioning. Together, information on diagnosis plus functioning provides a broader and more meaningful picture of the health of people or populations, which can then be used for decision-making purposes.
The WHO family of international classifications provides a valuable tool to describe and compare the health of populations in an international context. The information on mortality (provided by ICD-10) and on health outcomes (provided by ICF) may be combined in summary measures of population health for monitoring the health of populations and its distribution, and also for assessing the contributions of different causes of mortality and morbidity.
ICF has moved away from being a consequences of disease classification (1980 version) to become a components of health classification. Components of health identifies the constituents of health, whereas consequences focuses on the impacts of diseases or other health conditions that may follow as a result. Thus, ICF takes a neutral stand with regard to etiology so that researchers can draw causal inferences using appropriate scientific methods. Similarly, this approach is also different from a determinants of health or "risk factors" approach. To facilitate the study of determinants or risk factors, ICF includes a list of environmental factors that describe the context in which individuals live.
2. Aims of ICF
ICF is a multipurpose classification designed to serve various disciplines and different sectors. Its specific aims can be summarized as follows:
These aims are interrelated, since the need for and uses of ICF require the construction of a meaningful and practical system that can be used by various consumers for health policy, quality assurance and outcome evaluation in different cultures.
2.1 Applications of ICF
Since its publication as a trial version in 1980, ICIDH has been used for various purposes, for example:
Since ICF is inherently a health and health-related classification it is also used by sectors such as insurance, social security, labour, education, economics, social policy and general legislation development, and environmental modification. It has been accepted as one of the United Nations social classifications and is referred to in and incorporates The Standard Rules on the Equalization of Opportunities for Persons with Disabilities.  Thus ICF provides an appropriate instrument for the implementation of stated international human rights mandates as well as national legislation.
ICF is useful for a broad spectrum of different applications, for example social security, evaluation in managed health care, and population surveys at local, national and international levels. It offers a conceptual framework for information that is applicable to personal health care, including prevention, health promotion, and the improvement of participation by removing or mitigating societal hindrances and encouraging the provision of social supports and facilitators. It is also useful for the study of health care systems, in terms of both evaluation and policy formulation.
3. Properties of ICF
A classification should be clear about what it classifies: its universe, its scope, its units of classification, its organization, and how these elements are structured in terms of their relation to each other. The following sections explain these basic properties of ICF.
3.1 Universe of ICF
ICF encompasses all aspects of human health and some health-relevant components of well-being and describes them in terms of health domains and health-related domains.  The classification remains in the broad context of health and does not cover circumstances that are not health-related, such as those brought about by socioeconomic factors. For example, because of their race, gender, religion or other socioeconomic characteristics people may be restricted in their execution of a task in their current environment, but these are not health-related restrictions of participation as classified in ICF.
There is a widely held misunderstanding that ICF is only about people with disabilities; in fact, it is about all people. The health and health-related states associated with all health conditions can be described using ICF. In other words, ICF has universal application. 
3.2 Scope of ICF
ICF provides a description of situations with regard to human functioning and its restrictions and serves as a framework to organize this information. It structures the information in a meaningful, interrelated and easily accessible way.
ICF organizes information in two parts. Part 1 deals with Functioning and Disability, while Part 2 covers Contextual Factors. Each part has two components:
1. Components of Functioning and Disability
The Body component comprises two classifications, one for functions of body systems, and one for body structures. The chapters in both classifications are organized according to the body systems.
The Activities and Participation component covers the complete range of domains denoting aspects of functioning from both an individual and a societal perspective.
2. Components of Contextual Factors
A list of Environmental Factors is the first component of Contextual Factors. Environmental factors have an impact on all components of functioning and disability and are organized in sequence from the individual's most immediate environment to the general environment.
Personal Factors is also a component of Contextual Factors but they are not classified in ICF because of the large social and cultural variance associated with them.
The components of Functioning and Disability in Part 1 of ICF can be expressed in two ways. On the one hand, they can be used to indicate problems (e.g. impairment, activity limitation or participation restriction summarized under the umbrella term disability); on the other hand they can indicate nonproblematic (i.e. neutral) aspects of health and health-related states summarized under the umbrella term functioning).
These components of functioning and disability are interpreted by means of four separate but related constructs. These constructs are operationalized by using qualifiers. Body functions and structures can be interpreted by means of changes in physiological systems or in anatomical structures. For the Activities and Participation component, two constructs are available: capacity and performance (see section 4.2).
A person's functioning and disability is conceived as a dynamic interaction  between health conditions (diseases, disorders, injuries, traumas, etc.) and contextual factors. As indicate above, Contextual Factors include both personal and environmental factors. ICF includes a comprehensive list of environmental factors as an essential component of the classification. Environmental factors interact with all the components of functioning and disability. The basic construct of the Environmental Factors component is the facilitating or hindering impact of features of the physical, social and attitudinal world.
3.3 Unit of classification
ICF classifies health and health-related states. The unit of classification is, therefore, categories within health and health-related domains. It is important to note, therefore, that in ICF persons are not the units of classification; that is, ICF does not classify people, but describes the situation of each person within an array of health or health-related domains. Moreover, the description is always made within the context of environmental and personal factors.
3.4 Presentation of ICF
ICF is presented in two versions in order to meet the needs of different users for varying levels of detail.
The full version of ICF, as contained in this volume, provides classification at four levels of detail. These four levels can be aggregated into a higher-level classification system that includes all the domains at the second level. The two-level system is also available as a short version of ICF.
4. Overview of ICF components
An overview of these concepts is given in Table 1; they are explained further in operational terms in section 5.1. As the table indicates:
Table 1. An overview of ICF
4.1 Body Functions and Structures and impairments
4.2 Activities and Participation / activity limitations and participation restrictions
Table 2. Activities and Participation: information matrix
4.3 Contextual Factors
Contextual Factors represent the complete background of an individual's life and living. They include two components: Environmental Factors and Personal Factors - which may have an impact on the individual with a health condition and that individual's health and health-related states.
Environmental factors make up the physical, social and attitudinal environment in which people live and conduct their lives. These factors are external to individuals and can have a positive or negative influence on the individual's performance as a member of society, on the individual's capacity to execute actions or tasks, or on the individual's body function or structure.
Personal factors are the particular background of an individual's life and living, and comprise features of the individual that are not part of a health condition or health states. These factors may include gender, race, age, other health conditions, fitness, lifestyle, habits, upbringing, coping styles, social background, education, profession, past and current experience (past life events and concurrent events), overall behaviour pattern and character style, individual psychological assets and other characteristics, all or any of which may play a role in disability at any level. Personal factors are not classified in ICF. However, they are included in Fig. 1 to show their contribution, which may have an impact on the outcome of various interventions.
5. Model of Functioning and Disability
5.1 Process of functioning and disability
As a classification, ICF does not model the "process" of functioning and disability. It can be used, however, to describe the process by providing the means to map the different constructs and domains. It provides a multi-perspective approach to the classification of functioning and disability as an interactive and evolutionary process. It provides the building blocks for users who wish to create models and study different aspects of this process. In this sense, ICF can be seen as a language: the texts that can be created with it depend on the users, their creativity and their scientific orientation. In order to visualize the current understanding of interaction of various components, the diagram presented in Fig. 1 may be helpful.
Fig. 1. Interactions between the components of ICF
In this diagram, an individual's functioning in a specific domain is an interaction or complex relationship between the health condition and contextual factors (i.e. environmental and personal factors). There is a dynamic interaction among these entities: interventions in one entity have the potential to modify one or more of the other entities. These interactions are specific and not always in a predictable one-to-one relationship. The interaction works in two directions; the presence of disability may even modify the health condition itself. To infer a limitation in capacity from one or more impairments, or a restriction of performance from one or more limitations, may often seem reasonable. It is important, however, to collect data on these constructs independently and thereafter explore associations and causal links between them. If the full health experience is to be described, all components are useful. For example, one may:
Case examples in Annex 4 further illustrate possibilities of interactions between the constructs.
The scheme shown in Fig. 1 demonstrates the role that contextual factors (i.e. environmental and personal factors) play in the process. These factors interact with the individual with a health condition and determine the level and extent of the individual's functioning. Environmental factors are extrinsic to the individual (e.g. the attitudes of the society, architectural characteristics, the legal system) and are classified in the Environmental Factors classification. Personal Factors, on the other hand, are not classified in the current version of ICF. They include gender, race, age, fitness, lifestyle, habits, coping styles and other such factors. Their assessment is left to the user, if needed.
5.2 Medical and social models
A variety of conceptual models  has been proposed to understand and explain disability and functioning. These may be expressed in a dialectic of "medical model" versus "social model". The medical model views disability as a problem of the person, directly caused by disease, trauma or other health condition, which requires medical care provided in the form of individual treatment by professionals. Management of the disability is aimed at cure or the individual's adjustment and behaviour change. Medical care is viewed as the main issue, and at the political level the principal response is that of modifying or reforming health care policy. The social model of disability, on the other hand, sees the issue mainly as a socially created problem, and basically as a matter of the full integration of individuals into society. Disability is not an attribute of an individual, but rather a complex collection of conditions, many of which are created by the social environment. Hence the management of the problem requires social action, and it is the collective responsibility of society at large to make the environmental modifications necessary for the full participation of people with disabilities in all areas of social life. The issue is therefore an attitudinal or ideological one requiring social change, which at the political level becomes a question of human rights. For this model disability is a political issue.
ICF is based on an integration of these two opposing models. In order to capture the integration of the various perspectives of functioning, a "biopsychosocial" approach is used. Thus, ICF attempts to achieve a synthesis, in order to provide a coherent view of different perspectives of health from a biological, individual and social perspective. 
6. Use of ICF
ICF is a classification of human functioning and disability. It systematically groups health and health-related domains. Within each component, domains are further grouped according to their common characteristics (such as their origin, type, or similarity) and ordered in a meaningful way. The classification is organized according to a set of principles (see Annex 1). These principles refer to the interrelatedness of the levels and the hierarchy of the classification (sets of levels). However, some categories in ICF are arranged in a non-hierarchical manner, with no ordering but as equal members of a branch.
The following are structural features of the classification that have a bearing on its use.
Further coding guidelines are presented in Annex 2. Users are strongly recommended to obtain training in the use of the classification through WHO and its network of collaborating centres.
Table 3. Qualifiers
54 th World Health Assembly endorsement of ICF for international use
The resolution WHA54.21 reads as follows:
The Fifty-fourth World Health Assembly,
1. ENDORSES the second edition of the International Classification of Impairments, Disabilities and Handicaps (ICIDH), with the title International Classification of Functioning, Disability and Health, henceforth referred to in short as ICF;
2. URGES Member States to use ICF in their research, surveillance and reporting as appropriate, taking into account specific situations in Member States and, in particular, in view of possible future revisions;
3. REQUESTS the Director-General to provide support to Member States, at their request, in making use of ICF.
1 The text represents a revision of the International Classification of Impairments, Disabilities, and Handicaps (ICIDH), which was first published by the World Health Organization for trial purposes in 1980. Developed after systematic field trials and international consultation over the past five years, it was endorsed by the Fifty-fourth World Health Assembly for international use on 22 May 2001 (resolution WHA54.21).
2 These terms, which replace the formerly used terms "impairment", "disability" and "handicap" , extend the scope of the classification to allow positive experiences to be described. The new terms are further defined in this Introduction and are detailed within the classification. It should be noted that these terms are used with specific meanings that may differ from their everyday usage.
3 A domain is a practical and meaningful set of related physiological functions, anatomical structures, actions, tasks, or areas of life.
4 International Statistical Classification of Diseases and Related Health Problems, Tenth Revision, Vols. 1-3. Geneva, World Health Organization, 1992-1994.
5 It is also important to recognize the overlap between ICD-10 and ICF. Both classifications begin with the body systems. Impairments refer to body structures and functions, which are usually parts of the "disease process" and are therefore also used in the ICD-10. Nevertheless, ICD-10 uses impairments (as signs and symptoms) as parts of a constellation that forms a "disease", or sometimes as reasons for contact with health services, whereas the ICF system uses impairments as problems of body functions and structures associated with health conditions.
6 Two persons with the same disease can have different levels of functioning, and two persons with the same level of functioning do not necessarily have the same health condition. Hence, joint use enhances data quality for medical purposes. Use of ICF should not bypass regular diagnostic procedures. In other uses, ICF may be used alone.
7 The Standard Rules on the Equalization of Opportunities for Persons with Disabilities. Adopted by the United Nations General Assembly at its 48th session on 20 December 1993 (resolution 48/96). New York, NY, United Nations Department of Public Information, 1994.
8 Examples of health domains include seeing, hearing, walking, learning and remembering, while examples of health-related domains include transportation, education and social interactions.
9 Bickenbach JE, Chatterji S, Badley EM, stn TB. Models of disablement, universalism and the ICIDH, Social Science and Medicine, 1999, 48:1173-1187.
10 This interaction can be viewed as a process or a result depending on the user.
11 See also Annex 1, Taxonomic and Terminological Issues.
12 Although organ level was mentioned in the 1980 version of ICIDH, the definition of an "organ" is not clear. The eye and ear are traditionally considered as organs; however, it is difficult to identify and define their boundaries, and the same is true of extremities and internal organs. Instead of an approach by "organ", which implies the existence of an entity or unit within the body, ICF replaces this term with "body structure".
13 Thus impairments coded using the full version of ICF should be detectable or noticeable by others or the person concerned by direct observation or by inference from observation.
14 The definition of "participation" brings in the concept of involvement. Some proposed definitions of "involvement" incorporate taking part, being included or engaged in an area of life, being accepted, or having access to needed resources. Within the information matrix in Table 2 the only possible indicator of participation is coding through performance. This does not mean that participation is automatically equated with performance. The concept of involvement should also be distinguished from the subjective experience of involvement (the sense of "belonging"). Users who wish to code involvement separately should refer to the coding guidelines in Annex 2.
15 ICF differs substantially from the 1980 version of ICIDH in the depiction of the interrelations between functioning and disability. It should be noted that any diagram is likely to be incomplete and prone to misrepresentation because of the complexity of interactions in a multidimensional model. The model is drawn to illustrate multiple interactions. Other depictions indicating other important foci in the process are certainly possible. Interpretations of interactions between different components and constructs may also vary (for example, the impact of environmental factors on body functions certainly differs from their impact on participation).
16 The term "model" here means construct or paradigm, which differs from the use of the term in the previous section.
17 See also Annex 5 - "ICF and people with disabilities".
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