International classification of functioning, disability and health and its significance for rheumatology

The international classification of functioning, disability and health (ICF) has been developed by the World Health Organization (WHO) to describe health and handicaps in more detail in order to allow better classification and registration. The ICF comprises the disease, structure, functioning, activity and participation as well as corresponding factors related to the individual and the environment. By this means an integrated concept and assessment of biologic, individual and social aspects of health is attained. The ICF represents an essential addition to the international classification of diagnoses (ICD) and procedures (OPS). The ICF consists of two interelated parts. The first part that describes functioning and disability contains two components: one related to the body (functioning and structure) and one related to activity and participation. The second part describes the context factors (related to the environment and the individual). Body functions are the physical and mental functions of the organism. Body structures are the anatomically defined parts of the body. Activity describes how a task is solved or how an action can be performed and participation is the way in which an individual is involved in the environment and society. The ICF categories make the classification of all aspects of functioning and health in individuals easier and independent of diseases or specific assessment instruments. However, since there are more than 1,400 categories, the ICF cannot be used in daily practice in this form. Therefore, attempts are made to identify those parts of the ICF that are relevant for specific patients, situations and disease states or activities. These are the so-called ICF core sets. This article attempts to give an overview on the ICF, to provide an insight into recent work on the ICF related to musculoskeletal and rheumatic diseases and, finally, to describe how an ICF core set for patients with acute arthritis was made possible by means of a successful multicenter cooperative effort.