Excerpts from the W.H.O. Introduction to the ICIDH-2 (ICF)*

1. Background

This volume contains the International Classification of Functioning, Disability and Health, known as ICIDH-2. The overall aim of the ICIDH-2 classification is to provide a unified and standard language and framework for the description of health and health-related states. The revised classification defines components of health and some health-related components of well-being (such as education, labour, etc.). The ICIDH-2 domains can, therefore, be seen as health domains and health-related domains.

These domains are described from body, individual and societal perspectives by two basic lists: (1) body functions and structure; (2) activities and participation. As a classification, ICIDH-2 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 refers to all body functions, activities and participation as an umbrella term; similarly, Disability serves as an umbrella term for impairments, activity limitations or participation restrictions. ICIDH-2 also lists environmental factors that interact with all these constructs. In this way, ICIDH-2 provides a useful profile of individuals' functioning, disability and health in various domains.

ICIDH-2 belongs to the 'family' of classifications developed by the World Health Organization for application to various aspects of health. The WHO family of international classifications provides the language to code a wide range of information about health (e.g. diagnosis, func-tioning 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 International Classification of Diseases, Tenth Re-vision). Functioning and disability associated with health conditions are classified in ICIDH-2. The ICD-10 and ICIDH-2 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 ICIDH-2 on functioning . Together, information on diagnosis plus functioning provides a broader and more meaningful picture that describes the health of people or populations, which could be used for decision-making purposes.

2. Aims of ICIDH-2

ICIDH-2 is a multi-purpose classification designed to serve various disciplines and different sectors. Its specific aims can be summarized as follows:

• to provide a scientific basis for understanding and studying health and health-related states, outcomes and determinants;
• to establish a common language for describing health and health-related states in order to improve communication between different users, such as health care workers, researchers, policy-makers and the public, including people with disabilities;
• to permit comparison of data across countries, health care disciplines, services and time;
• to provide a systematic coding scheme for health information systems.

These aims are interrelated, since the need for and uses of ICIDH-2 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 ICIDH-2

Since publication of the first trial version in 1980, ICIDH has been used for various purposes, for example:

• as a statistical tool - in the collection and recording of data (e.g. in population studies and surveys or in management information systems);
• as a research tool - to measure outcomes, quality of life or environmental actors;
• as a clinical tool - in needs assessment, matching treatments with specific conditions, vocational assessment, rehabilitation and outcome evaluation;
• as a social policy tool - in social security planning, compensation systems and policy design and implementation;
• as an educational tool - in curriculum design and to raise awareness and undertake social actions.

Although ICIDH-2 is inherently a health-related classification, it is also used by other sectors such as insurance, social security, labor, education, economics, social policy and general legislation development, and environmental modifications. Thus 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. As such, ICIDH-2 pro-vides an appropriate instrument for the implementation of stated international human rights mandates as well as national legislation.

ICIDH-2 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, which 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.

*As of 6/18/01, this is WHO's most recent statement on the classification. "can be substituted for "ICIDH-2" in every case. SOURCE: http://www.who.int/icidh/intro.htm