Conceptual Models of Disability and Functioning

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Introduction

Historically approaches towards health and disease has been very much focused on the medical or biological model where a person’s ill-health was exclusively thought to be related to pathology and treated purely by medical means. In more recent times thinking has moved towards a more functional model.

Biomedical Model

The biomedical model of disability is focused on pathology and impairment. It assumes several unhelpful notions about the nature of disability.The philosophy of Western medicine has traditionally been to treat and to cure, but in rehabilitation these outcomes are unlikely and the aim has often been to ‘normalise’. This philosophy was reinforced by the initial WhO classification that produced a distinction between impairment, dis- ability, and handicap. The biomedical model of disability usually implies that the physician takes a leading role in the entire rehabilitation process—being team leader, organising programmes of care, and generally directing the delivery of services for the person with disabilities. The doctor/patient relationship was the senior relationship in the medical model. Rehabilitation was born around the time of the First World War when there was a strong philosophy of the doctor telling injured servicemen how to behave, how to get better, and how to get back as quickly as possible to active duty. Such a model may have been appropriate in that cultural context but not in wider society today.

Social Model

The social model of disability understands disability as secondary to the social, legislative, and attitudinal environment in which the person lives and not any underlying medical condition. Although a person’s abilities may be different, the disability is because society either actively discriminates against the person with a disability or it fails to account for their different needs. The key features of the social model are listed in Box 1.2.2

Biopsychosocial Model

The biopsychosocial model of disability is an attempt to account for both the social and biomedical models of disability. First conceptualised by George Engel in 1977, it suggests that to understand a person's medical condition it is not simply the biological factors that need to be considered, but also the psychological and social factors .

• Bio (physiological pathology)
• Psycho (thoughts emotions and behaviours such as psychological distress, fear/avoidance beliefs, current coping methods and attribution)
• Social (socio-economical, socio-environmental, and cultural factors such as; work issues, family circumstances and benefits/economics)

International Classification of Functioning, Disability and Health

The WHO International Classification of Functioning, Disability and Health is underpinned by the Biopsychosocial Model. There is controversy over this approach, and some who use the social model of disability disagree with approaches that include aspects of health within a model of disability, as they would define disability as being solely due to a lack of response in changing the environment to accommodate the needs of the person. There are weaknesses in the ICF model, principally around personal context and well-being, and philosophies around the biopsychosocial model are still developing.4,5

Impairment is a medically descriptive term that says nothing about consequence. For example, a right hemiparesis, a left-sided sensory loss, and a homonymous hemianopia are all impairments but the consequences of each of these will depend on many other factors, such as the person’s environment, their job, family role, lifestyle, and expectations.

Activity describes the everyday tasks that any person, wherever they live, would be expected to do as a basic part of life, for instance, walking or eating. There is an overlap with participation and there is a judgement involved in relation to societal norms as to what these everyday tasks are.

Participation is defined as involvement in a life situation. It will vary considerably between people, for instance, having a mild right hemiparesis may have profound implications for a young person wanting to join the armed forces, as such occupations may be closed to him/her or an existing job may be lost. however, for a retired person with comorbidities, a similar impairment may have no perceptible impact on lifestyle. participation is often optimised by changing environmental factors, for example, a receptionist with a hemiparesis remains capable of undertaking the job and being a valuable member of the workforce if appropriate modifications are made to IT equipment. Another example is a person who needs to use a wheel- chair but cannot move around the office because it is not wheelchair accessible. In both cases, the employer’s attitude may cause the person to be moved elsewhere or even lose their job. The change necessary here is attitudinal, legislative, or both. Therefore, rehabilitation includes addressing aspects such as societal attitudes and the physical environment, which are traditionally outside the realm of medicine. A rehabilitation medicine doctor would not undertake that change themselves, as that is not where their skills lie. however, part of their duty is to identify the issue, give appropriate information, and send appropriate referrals to advocate on the patient’s behalf.

The full ICF is a detailed and lengthy document. The ICF recognises the importance not only of describing the functioning of an individual but also placing such functioning into its social context.

Rehabilitation medicine focuses not on the impairments and pathologies, but rather on activity and participation, attempting to optimise these according to what is felt to be important by the individual involved. This is operationalised by identifying the aims or goals the person may have. This may include addressing aspects of pathology and impairment, but the overall aim or goal is at the level of activity or participation. Changing aspects of the environment or the ways in which a person performs an activity are often the key changes that lead to that person achieving their goal. Rehabilitation medicine does not minimise the importance of diagnosis and impairment but sees addressing these as part of a whole spectrum of ways to achieve a person’s goals. As the primary skills of a doctor are often in the area of pathology and impairment whereas those of allied health professionals are more in activity and participation, it often falls to the doctors within the multidisciplinary team to be the professionals who are most involved with pathology and impairment, and this can cause a tendency to revert to the medical model. The skill of a rehabilitation doctor is dependent on being able to take an informed overview of the whole ICF spectrum.

Functioning

Other Models

Human Development Model – Disability Creation Process (HDM-DCP)

The Human Development-Disability Creation Process is a conceptual model which aims to document and explain the causes and consequences of diseases, trauma, and other effects on integrity and the development of the person, the HDM-DCP is designed to be used by ethos concerned with the adaptation, rehabilitation, social participation and exercise of human rights of people with disabilities and their families.

The HDM-DCP shows that the accomplishment of life habits can be influenced by reinforcing our abilities and compensating for our disabilities through rehabilitation, but also by reducing environmental obstacles stemming. An obstacles coud be, for example, a prejudice, the lack of assistance or resources, the lack of accessibility at home and at school, a problem in obtaining adapted printed information or moving around with the help of accessible signage.

Thus, measuring the accomplishment of life habits means that we identify the result of the interaction between the person and his/her environment. Here we are referring to an indicator of the quality of social participation: It is measured over a continuum or scale ranging from an optimal situation of social participation to a complete disabling situation.

References