Functioning is a central dimension in patients experiencing or likely to experience disability. Accordingly, concepts, classifications and measurements of functioning and health are an important key to clinical practice, research and teaching.

Within this context, the approval of the International Classification of Functioning, Disability and Health (ICF) by the World Health Assembly in May 2001 is considered a landmark event. The ICF establishes the beginning of a new era of patient-oriented clinical practice, research, and teaching.

The ICF is based on the integrative bio-psycho-social model of functioning, disability and health of the World Health Organization (WHO). As such, functioning, with its components, Body Functions and Structures and Activities and Participation, is viewed in relation to the health condition under consideration, as well as personal and environmental factors.

Functioning is the human experience in relation to body functions, structures and activity. It is also measured by the level of interaction with health conditions and personal and environmental factors.

Disability, on the other hand, is the human experience of impaired body functions and structures, activity limitations and participation restrictions between health conditions, personal and environmental factors.

Although disability is usually the preferred term, the distinction can help when reading medical literature. And from the bio-psycho-social perspective presented here, functioning is implicitly addressed when disability is studied and vice versa.

This integrative bio-psycho-social model, and the way it describes functioning and disability, corresponds with the perspective of rehabilitation medicine.

The rehabilitative process targets functioning, the environment and modifiable personal factors because functioning is seen in close interaction with the environment and the person’s characteristics.

Moreover, in rehabilitation, functioning represents not only an outcome, but also the starting point of the clinical assessment, the intervention management, and the evaluation and quality management.  more