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Functional capacity evaluations – do they predict function in the ‘real world’?

Posted Aug 13 2009 6:27pm

What do you do when a client has a goal ‘to establish functional abilities for work’, spends a lot of time looking at setting baselines at home, develops a good knowledge of how to maintain consistency, starts to work and sustains abilities in a specific workplace, then completes a functional capacity evaluation that says he can do more than what he’s identified he can?

I’ve had a long-standing interest in whether functional assessments carried out in a clinic or work setting over a single session (or even two-day period) can predict sustainable function in a ‘real world’ setting such as work. There are many different types of ‘work sampling’ methods that purport to measure functional ability, ranging from specialised machines and standardised set-ups like Valpar to Isernhagen to simple ‘lift and carry’ and walk, crouch or squat tests carried out by occupational and physiotherapists.

Most of these tests have some degree of reliability – that is, they can be carried out by two different people or over two different times and the result will be the same. What they do seem to lack is validity – specifically, predictive validity. What this means is that they don’t have a good track record of being able to predict from the results of the testing whether someone can actually return to work, or even a specific job.

There are quite a few reasons for this – most FCE’s sample what a person WILL do within a clinic setting over a relatively short period of time. Issues of tolerance or performance consistency over an eight hour day or 40 hour week are not sampled, neither are the tasks carried out in the same way or under the same conditions as in a real work setting (like having a deadline, need to make a profit, boredom, having an argument with a coworker – or even the same sort of container, starting position or lighting).

FCE’s can’t establish what a person CAN do (I don’t know of any way to establish this!), simply what the person will do on that day. So if the person is fearful of increasing pain (or worse – harming him/herself), or hasn’t carried out that specific activity for a long time, or even if the person is worried about what the assessment findings will mean in terms of the future – well, their performance may be a lot lower than what they would do in a completely different setting.

More than these factors, though, is that FCE’s don’t measure some of the most important factors that predict whether a person will return to work – I know of only one FCE that integrates psychosocial factors relevant to return to work within the testing format. Some testing batteries include questionnaires but don’t integrate the findings from these with the results of the assessment. Most place the majority of emphasis on biomechanical factors – can the person walk, bend, twist, reach, carry and lift?

In my client’s case, as a result of his FCE, he experienced a real increase of his pain. This is quite normal – even people without chronic pain experience an increase in their pain the day after they’ve completed a standard FCE (Soer, R; Groothoff, J; Geertzen, JHB; et al. 2008). He coped quite well with the increase, but for some people this is a real problem – especially those who haven’t developed effective flare-up management plans, or who catastrophise. On the other hand, he also recognised that he wouldn’t be able to sustain the level of performance he’d achieved during the test. This meant that, to him, the results were inaccurate, and he felt quite fearful that they would be misinterpreted by people who were unaware of the limitations of an FCE.

As a health professional, one job I take quite seriously is to help people recognise the limitations of various investigations and assessments. This is an ethical responsibility in terms of the assessments I conduct and on which I report. For example, if I was doing cognitive testing I’m ethically bound to advise the client that the results obtained on such a test would not be the same as what they would achieve in the ‘real world’.

I often discuss the limitations of MRI, CT and x-ray with people who have pain. Most of them have a strong belief in the value of these tests to ‘detect pain’ – it’s mistaken. There are many people with quite marked changes on radiological investigations that have no pain, while I can’t think of one instance where these investigations show pain. Similarly, I think it’s important to discuss the limitations of other testing procedures – one of them being functional capacity evaluations.

The results from FCE’s do have limitations, and for clients who are anxious about their ability, perhaps have spent much of their rehabilitation time learning how to reduce their level of activity so they can achieve consistent and reliable performance, it’s important to help them understand these limitations and trust what they have learned for themselves.

Unfortunately, this may not be what a case manager wants to hear. After all, they have a process to follow, and a degree of trust in the results. It must be unsettling to have one health professional critique the validity of an assessment carried out by another health professional. I can recognise the desire for case managers and others within a compensation environment to try to find some way to ‘objectively’ determine whether someone can or can’t do specific tasks.

But – and you knew there would be a ‘but’ – in this case, the ‘objectivity’ of a functional capacity evaluation doesn’t mean that it is providing a measurement that means anything with regard to return to work. Reliability is a great thing for an assessment to have, but a measure can be reliably measuring the wrong thing.

What can a functional capacity evaluation measure? It measures what a person will do in a clinical testing situation on a given day or days over a specific set of activities. It does not measure ‘can do’, it measures ‘will do’, and it doesn’t measure ‘can do at work’, it measures ‘will do here and now’.

For some interesting reading on FCE, take a look at the following readings:
Geisser ME. Robinson ME. Miller QL. Bade SM. (2003). Psychosocial factors and functional capacity evaluation among persons with chronic pain. J ournal of Occupational Rehabilitation Dec;13 (4):259-76

Gibson, Libby; Strong, Jenny; Wallace, Alison.(2005). Functional Capacity Evaluation as a Performance Measure: Evidence for a New Approach for Clients With Chronic Back Pain. Clinical Journal of Pain. Vol 21 (3) May-Jun , 207-215.

Reneman, Michiel F; Jorritsma, Wim; Schellekens, Jan M. H; Goeken, Ludwig N. H.(2002). Concurrent validity of questionnaire and performance-based disability measurements in patients with chronic nonspecific low back pain. Journal of Occupational Rehabilitation. Vol 12 (3) Sep, 119-129.

Soer, R., Groothoff, J., Geertzen, JHB., van der Schans, C P., Reesink, DD., Reneman, M F., (2008). Pain response of healthy workers following a functional capacity evaluation and implications for clinical interpretation. Journal of Occupational Rehabilitation. 18 (3) Sep 2008, 290-298

Wallbom AS. Geisser ME. Haig AJ. Yamakawa K. Montgomery D. (2002). Concordance between rating of perceived exertion and function in persons with chronic, disabling back pain. Journal of Occupational Rehabilitation. 12 (2):93-8

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