Analysis of disability

Disability is the central concern of rehabilitation, just as disease is the paramount concern of biomedical practice. The analysis of disability is often the best starting point when developing a formulation. This page outlines a systematic approach to the investigation of disability. The process is similar to that put forward for other domains of the biopsychosocial model of illness on other pages. The process studies the interrelationship between disability and each different field. The clinician needs to remember that disability refers to a person’s goal-directed behaviour and that most behaviour is influenced by the patient’s context at the time. The effects of context may explain inconsistencies in performance. The MindMap graphic here illustrates the approach, and you might find it helpful to have it open in a second tab. It is also shown below.

Disability refers to the interaction between individuals with a health condition (e.g., cerebral palsy, Down syndrome and depression) and personal and environmental factors (e.g., negative attitudes, inaccessible transportation and public buildings, and limited social supports).

World Health Organisation.
Disability and Health.
Fact Sheet 24th November 2021

Table of Contents


Most patients attend rehabilitation services because they have activities they cannot undertake as they would wish. The second common reason is troublesome symptoms, and I discuss the analysis of symptoms, and impairments, on another page. Thus, the study of disability is perhaps the essential skill needed by every rehabilitation expert. Most healthcare professionals will learn much about impairments in their undergraduate and early postgraduate training. Understanding disability and its place within the holistic biopsychosocial model of illness receive less emphasis in early training. (here)

An activity is a behaviour undertaken to achieve a goal. Most people think that activities are physical, such as walking, getting dressed, or doing some work from the outside, all aimed at a physical goal. Communicating and solving puzzles or problems are also activities, albeit ones that require little muscular activity. The goals are less tangible, no less critical, easily judged as achieved or otherwise by the patient, and, in principle, can also be measured.

All goals may include non-physical components that are, to the person, of great significance. They are qualitative judgements about the standard of performance. Someone may not appreciate walking safely and fast if they have a limp, or they might want their speech to have an accent they have lost.  

Moreover, there is much more to undertaking an activity than achieving the apparent and immediate practical goal. There is meaning attached to activities both by the person and by others. Succeeding in dressing well without help and looking smart means that I am independent and careful about my looks. However, dressing slowly, with clothes that need washing and leaving buttons undone, suggests I need help and support. Similarly, undertaking a work task carelessly and slowly means I have issues, whereas completing the task ahead of schedule and at a high standard indicates a desire to help.

Put another way, people undertaking an activity are often also enacting a role, and other people may also interpret their performance as indicating a position. Attaching social meaning to actions is always true for everyone. Suppose I sit behind a desk and ask a person what they have been doing and why. I could be a doctor exploring a person’s rehabilitation problems or a police detective looking for criminal activity or motivation. The content will be similar; the context indicates what the roles are.

Thus, it is essential to be aware that the goal of behaviour may be other than the apparent outcome or that there may be several goals, not all obvious. For example, if a patient with multiple sclerosis knows that they will only receive a disease-modifying drug if they report walking more than 400 metres, they are likely to say that. The criterion is rarely actually tested, but they would be very motivated to succeed if it were.

In contrast, another patient with multiple sclerosis may realise that acquiring a benefit such as a ‘blue badge’ to allow free parking depends on not being able to walk 10 metres. Neither of these patients is dishonest; we all have several goals in mind during many of our activities.

In summary, when analysing a disability, it is crucial to think much more broadly, consider what behaviour means, and allow for the powerful effect of context on the activity being observed or asked about.

A systematic approach

To approach a problem systematically, you need a ‘system’ that provides a logical and comprehensive framework so that you are sure to consider all essential aspects. The framework in all rehabilitation is the biopsychosocial model of illness, which successfully enables a systematic approach.

However, the biopsychosocial model only gives a general structure, with eight separate domains, and often a more detailed framework is needed. For example, within pathology and impairment, the systematic approach based on the biomedical model of illness is sound, structuring disease and symptoms and signs around the body’s anatomy and physiology.

When considering disability, there is no pre-existing model or system. The phrase, activities of daily living has emerged within rehabilitation to describe limited actions, but this phrase is imprecise and used differently by different people. Various adjectives, such as instrumental, domestic, community, and personal, have been used to classify activities. None are comprehensive or widely used.

With additional training detail, the system can be seen on pages 26-31 of the published curriculum here. I will describe it below. The problem faced and not overcome is that high-level activities such as working or shopping depend considerably upon lower-level activities such as walking, talking, and manual dexterity. Thus the activities cannot be considered independent from each other. Nonetheless, it is a helpful classification worth exploring.

When developing the UK curriculum for training in Rehabilitation Medicine, the General Medical Council suggested we write a table of “presentations and conditions”. The example was from the internal medicine curriculum, where the authors based the “presentation and conditions” on the body’s central organ systems. A system based on bodily organs was not appropriate for a rehabilitation curriculum, so we developed our system that attempted to cover all activities without being too long. You can find it in the curriculum, pages 24-31.

UK Training curriculum system

In the table below, I name each activity domain and give a brief description.

This category includes: all transfers, getting around the house, using stairs and steps, getting into and out of the house, going around the local community, using public transport, and driving.
This category covers all arm functions, both bimanual and using one arm where necessary or appropriate.
Continence and toileting.
This class of activities covers the management of excretion, bowels and bladder, including using a toilet. It would include colostomy and catheter care where the patient uses them.
Feeding and swallowing.
This category encompasses getting food and fluids to the mouth, chewing, and swallowing. It does not include food preparation.
Personal care.
This group encompasses washing, including shaving and cleaning teeth, doing make-up, brushing hair, selecting and putting on clothes and shoes.
Domestic activities.
This class included all activities that someone undertakes within the home: cooking, cleaning, washing and caring for clothes, minor do-it-yourself repairs, looking after a small garden,
Community activities.
This category includes shopping (including online), travel, going to social venues, and religious activities.
Vocational activities.
This group covers employment and paid work, voluntary activities for or with others, and participation in training or educational activities.
Leisure activities.
This category encompasses all social, group, team or individual activities, covering intellectual and physical activities.
This category includes all communication activities: verbal and non-verbal, oral and written, ability to speak and ability to use language. It focuses on the ability to communicate ideas, facts, wishes etc. This category links into the next, social interaction.
Social interaction.
This class focuses on the activity of communicating and interacting with other people in any setting. Covers the content and style of interaction and behaviour with others, both verbal and non-verbal, and the ability to make and maintain friendships.
Partner relationships.
Includes the ability to make and maintain a partner relationship, sexual activities, childcare, and fulfilling other family or partner responsibilities.
Citizen activities.
This category includes participation in political and democratic activities, interacting with government and statutory bodies, and managing all bureaucratic necessities associated with being a citizen.
This group of activities includes setting goals, planning activities, solving problems faced in day-to-day life, learning, and adapting to change.

WHO Disability Assessment Scales

The World Health Organisation (WHO) faced a similar problem when developing its disability schedules for use across all conditions. It generated some Disability Assessment Schedules (DAS) for a generic and comprehensive assessment of activity limitations. (here) You can download a book describing the development and showing the scales here, and you may download a copy of the 36-item scale here. From a practical perspective, these scales are well-developed. They have a full 36-item version and a short 12-item version. They have arrangements to be completed by the patient, a family member, or a professional, and they are available in many languages.

The 36-item version is sub-divided into six domains:

  • Understanding and communicating
  • Getting around
  • Self-care
  • Getting along with people
  • Life activities
  • Participation in Society

The 12-item version has questions on difficulties with:

  • Standing for extended periods such as 30 minutes?
  • Taking care of your household responsibilities?
  • Learning a new task, for example, learning how to get to a new place?
  • How much of a problem did you have joining in community activities (for example, festivities, religious or other activities) in the same way as anyone else can?
  • How much have you been emotionally affected by your health problems?
  • Concentrating on doing something for ten minutes?
  • Walking a long distance such as a kilometre [or equivalent]?
  • Washing your whole body?
  • Getting dressed?
  • Dealing with people you do not know?
  • Maintaining a friendship?
  • Your day-to-day work?

Two things are apparent when comparing the WHO DAS with the UK curriculum system. The first is that there is probably no system which will suit all situations. The second is that both emphasise social activities, in notable contrast to the usual focus on convenient and measurable activities in clinical practice and research.

Analysis of disability

I show a systematic approach to the analysis of disability in the MindMap graphic below, which can be downloaded here. The process is based on the biopsychosocial model of illness and is, I hope, self-explanatory. I will only add a couple of points here.

Whenever you encounter a discrepancy between observed (or reported) performance and your expectation about capability, always put yourself in the patient’s position and consider your goals. All activities are influenced to a greater or lesser extent by the context and the patient’s goals, especially their longer-term goals.

You could start a discussion with the patient in a supportive, non-judgmental manner, remarking on your observation that the performance is not as you would expect and does he have any idea why this might be so? Alternatively, you could observe the patient’s performance in several different situations, especially when the patient will not feel that you are assessing his performance.

Next, one should always consider the influence of mood, including fear and lack of confidence, and the effect of the patient’s beliefs and expectations. These may have a powerful impact on the performance of activities and are sometimes amenable to alteration through specific treatments.

Third, stigma may be a potent cause of activity limitation in some people. The patient may feel ashamed of or embarrassed by the quality of their performance. The patient might also, often correctly, believe that others will notice their difficulties, judge their performance, and interpret it negatively, assuming that the patient has a mental illness or cognitive loss.

It is rarely appropriate or correct to attribute apparent underperformance to a lack of motivation because motivation is an intervening variable between performance and some other primary cause, such as the activity not being one the person wants to undertake. Whenever someone suggests a patient lacks motivation, you must ask, why is motivation lacking?


The analysis of disability always requires attention to every part of the biopsychosocial model of illness because every aspect can significantly affect the performance of activities. When you do not understand why a disability is as it is, the crucial skill needed is putting yourself in the person’s shoes and then considering how you would act. Most patients act rationally, and the clinician needs to discover the rationale behind the observed activities.

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