Intended for healthcare professionals


Assessing the ability to work

BMJ 2008; 336 doi: (Published 06 March 2008) Cite this as: BMJ 2008;336:519
  1. Jos Verbeek, occupational physician1,
  2. Frank van Dijk, occupational physician2
  1. 1Cochrane Occupational Health Field, Knowledge Transfer Team, Finnish Institute of Occupational Health, Kuopio, Finland
  2. 2Coronel Institute of Occupational Health, Academic Medical Centre, Amsterdam, Netherlands

New UK test claims to be fair but lacks rigorous scientific evaluation

Recently, the Department of Work and Pensions in the United Kingdom announced a renewal of the personal capacity assessment. The report states that the renewal is expected to result in 20 000 fewer people claiming sickness benefits each year. It also claims that the new test is more robust, accurate, and fair than the previous one.1

Two issues are at stake here: firstly, the provision of work and a decent income for millions of people with disabilities and, secondly, the billions of pounds that society is willing and able to pay in disability benefits.In many European countries, the growing numbers of people claiming disability benefit and expenditure on these benefits is an important point of political interest.2

The personal capacity assessment lists 17 activities, each of which can be given a score according to the degree of limitation. People with a score of 15 or more are assessed as unable to work. Changes have been made to the 17 activities and limitations in the new assessment; for example, not being able to walk more than 30 metres had the highest disability score in the old assessment but this has been changed to 50 metres in the new one. Other changes make it more difficult to reach the highest level of work disability.

It is generally agreed that the World Health Organization (WHO) model of functioning provides the best framework for the evaluation of disability.3 The basis of this model is that disability has three major components apart from having a disease: impairments in bodily or mental functions or structures, limitations in activities, and restrictions in participation in societal roles. Personal and environmental factors also play a role.

It is important for doctors to understand the essential difference between having a disease and having a disability.4 The ability to work depends on balancing the limitations in activities with the demands that participation in working life imposes. The personal capacity assessment does reflect the WHO model in that the test items refer to limitations in activities and the cut-off scores refer to the demands that work in general imposes on us. The cut-off score provides an indication of the severity of the limitations.

The new test claims to be fair and accurate, but the report does not define what this means. The test was evaluated against expert opinion in 212 cases. Even though essential qualifiers like sensitivity and specificity of the test are not reported, it is implied that specificity is higher and sensitivity is lower in the new test. Instead of referring to the usual trade-off between specificity and sensitivity, the authors of the report argue that the decrease in sensitivity occurred by chance. This is important because a decrease in sensitivity means that more disabled workers would be denied benefits. Even though the Department of Work and Pensions claims that the personal capacity assessment is the best assessment of its type in the world, we found no scientific reports on its validity in Medline. Such an important test deserves better scientific underpinning and evaluation.

Even within Europe, disability assessment varies widely, with some countries relying totally on strict rules and others on doctors’ expertise.5 In the Netherlands, doctors working for insurance companies use a Dutch variant of the personal capacity assessment called the (remaining) functional abilities list.6 The abilities on the Dutch list are more work oriented than those on the UK list, and the scores for severity of limitations are different. For example, the most severe Dutch limitation is not being able to lift 1 kg compared with 0.5 kg in the UK. However, neither the Dutch nor the UK system has been properly evaluated, so we do not know which is best.

Surprisingly, no scientific evidence is available on the diagnostic accuracy of these tests and questionnaires that are used for evaluating disability. The few reports that exist on disability assessment are mainly related to sickness certification and the equipment used to evaluate functional capacity.7 8 This may be because the way society deals with disability is deeply embedded in culture and disability is a politically sensitive matter.2 Subjecting the topic to scientific evaluation might be too confrontational or politically risky because the results might fundamentally challenge current practice.

The lack of use of evidence in general in insurance medicine has been noted by the Dutch Health Council, which therefore promotes evidence based disability assessment and produces guidelines for doctors working for social insurance companies.9 In addition, the Dutch Employee Insurance Schemes Implementing Body has collaborated with universities to form the Research Centre for Insurance Medicine, with the intention of improving the quality of disability assessment and guidance on reintegration.

Clinicians and researchers are increasingly interested in their patients’ ability to work and how to help them return to work, especially those with back pain, rheumatoid arthritis, and cancer.10 The expertise they have gained should be put to better use in evaluating disability.

Employers have a relatively negative image of people with disabilities and many are reluctant to offer jobs.11 Once a disabled person leaves the work force it is difficult for him or her to return. The Organisation for Economic Cooperation and Development therefore advises tailored intervention during the first few weeks of sick leave. This approach has been evaluated and found to be successful in the Netherlands.12 Doctors can therefore help their patients with disabilities the most by supporting them in retaining their jobs.3


  • Competing interests: None declared.

  • Provenance and peer review: Commissioned; not peer reviewed.