An important basis for the successful development of rehabilitation practice and research is a conceptually sound description of rehabilitation understood as a health strategy based on a universally accepted conceptual model and taxonomy of human functioning. With the approval of the International Classification of Functioning, Disability and Health (ICF) by the World Health Assembly in 2001 and the reference to the ICF in the World Health Assembly's resolution on "Disability, including prevention, management and rehabilitation" in 2005, we can now rely on a universally accepted conceptual model. It is thus time to initiate the process of evolving an ICF-based conceptual description that can serve as a basis for similar conceptual descriptions and according definitions of the professions applying the rehabilitation strategy and of distinct scientific fields of human functioning and rehabilitation research. In co-operation with the Physical and Rehabilitation Medicine (PRM) section of the European Union of Medical Specialists (UEMS) and its professional practice committee, we present a first tentative version of an ICF-based conceptual description in this paper. A brief definition describes rehabilitation as the health strategy applied by PRM and professionals in the health sector and across other sectors that aims to enable people with health conditions experiencing or likely to experience disability to achieve and maintain optimal functioning in interaction with the environment. Readers of the Journal of Rehabilitation Medicine are invited to contribute towards achieving an internationally accepted ICF-based conceptual description of rehabilitation by submitting commentaries to the Editor of this journal.

There is strong evidence that population ageing and the epidemiological transition to a higher incidence of chronic, non-communicable diseases will continue to profoundly impact societies worldwide, putting more pressure on healthcare systems to respond to the needs of the people they serve. These trends argue for the need to address what matters to people about their health: limitations in their functioning that affect their day-to-day actions and goals in life. From its inception, rehabilitation, 1 of the 4 health strategies identified in the Declaration of Alma Ata in 1978, has had functioning as its outcome of interest. Its practitioners are from fields that include physical and rehabilitation medicine, occupational therapy, physiotherapy, speech and language therapy, orthotics and prosthetics, psychology, and evaluators of functioning interventions, including assistive technologies. Demographic and epidemiological trends suggest that the key indicators of the health of populations will be not merely mortality and morbidity, but functioning as well. This, in turn, suggests that the primary focus of healthcare will need to respond to actual healthcare demands generated by the need for long-term management of chronic conditions, including, in particular, the scaling up and strengthening of rehabilitation. This is the case for thinking that rehabilitation will become the key health strategy of the 21st century.

One major change to the conceptual description of rehabilitation is the explicit integration of the perspective of the disabled person. The relationship between person and provider is characterized as a partnership. However, it is argued that quality of life should not be introduced as a primary goal of rehabilitation. This conceptual description can foster a common understanding of the rehabilitation professions and provide a point of departure for clarifying the role of different professions and services within the broad field of rehabilitation. It can also serve to position rehabilitation as a major health strategy and to sharpen the perception of rehabilitation among external stakeholders.

Patients hospitalized for an acute illness or injury are at risk of experiencing a significant loss of functioning as defined by the International Classification of Functioning, Disability and Health (ICF). The risk of a significant loss of functioning is increased in critically ill patients, in patients with complications or long-term intensive care stays, in persons with disabilities or with pre-existing chronic conditions and in the elderly. Early identification of rehabilitation needs and early start of rehabilitation can reduce healthcare costs by reducing dependence and nursing care, length of stay and prevention of disability. Two principles of rehabilitation for acute and early post-acute care can be distinguished. First, the provision of rehabilitation by health professionals who are generally not specialized in rehabilitation in the acute hospital. And second, specialized rehabilitation care provided by an interdisciplinary team. There is large variation how this specialized, typically post-acute rehabilitation care is organized, provided, and reimbursed in different countries, regions, and settings. For instance, it may be provided either in the acute hospital or in a rehabilitation or nursing setting. Most in-patients do not receive specialized rehabilitation at all during their whole stay in the acute hospital. But, it is important to point out that health professionals working in acute hospitals and who are not specialized in rehabilitation need to be able to recognize patients' needs for rehabilitation care and to perform rehabilitation interventions themselves or to assign patients to appropriate rehabilitation care settings. The principles outlined in this paper can serve as a basis for the development of clinical assessment instruments to describe and classify functioning, health and disability of patients receiving acute or early post-acute rehabilitation care.

A formal consensus process integrating evidence and expert opinion based on the ICF framework and classification led to the definition of ICF Core Sets for breast cancer. Both the Comprehensive ICF Core Set and the Brief ICF Core Set were selected.