One of the hallmarks of chronic pain is the effect on functional performance. It’s for this reason alone that an assessment of function needs to be a major part of any comprehensive pain assessment. This, however, is probably where agreement begins – and ends.
Function is all about doing, and in this kind of pain assessment, what I’m interested in is how the person with pain goes about engaging in activities that are important and necessary to him or her. Like any measure, the sum weight a person can shift in a manual handling task means very little without some sort of context. I’m more interested in how the person planned the movements; the quality of his or her movements; the pace the person moved; the thoughts or images that went through the person’s mind during the task; whether that weight represents a bag of spuds or a baby or the final brick in a wall the person’s building; and finally, what kind of weights can people of similar age and gender and general activity level manage? You see, without these contextual elements it’s impossible to draw conclusions about the meaning of that number.
The point I want to make is that it’s relatively simple to draw up a set of standardised movements to ask someone to perform. What’s difficult is to make sense of what is observed during a physical performance test – and both to ensure the measures are carried out consistently (reliably) and that those measures are valid, in other words that they measure what we need to know about.
So far, despite scouring the literature, I haven’t been able to identify any standardised ‘Functional Capacity Evaluations’ or physical performance batteries that have either reliability or validity established.
What this means is that I’m not sure that there has been sufficient work carried out to determine the range of activities that people with chronic pain find difficult, and the best way to reliably test the constructs that lie behind those difficulties – and then the best way to measure clinically relevant change.
What happens at the moment? Well, where I work, we have struggled with this problem for a long time, and we don’t have a really good answer right now, so this is one way of assessing function.
- Physical examination of range of movement and functional strength. The bread and butter of a musculoskeletal physiotherapist I think! This aspect can be carried out by our medics, but it’s not always a bad thing to have it also carried out by physiotherapists – the underlying reason for the assessment is different. While a doctor is looking to make a diagnosis of some sort of pain condition, the reason we might want to look at ROM and strength is to determine the impact on functional activity. So if the person has limited ROM at the hip and knee on passive testing, we’d be reasonably certain that this would transfer into trouble with stairs and kneeling.
Caveats? I’m not sure there is good inter-rater reliability for ROM and strength testing, and these are physical performance tests, in other words they’re behaviours – so we rely on the patient’s goodwill to perform ‘to the best’ of their ability. We can’t detect faking, no-body can, end of story. Don’t push me on this, kthx.
- Cardiovascular or endurance testing. Something like a bike test, step test, six minute walk test. There are loads of problems with this type of test in people with chronic pain – after all, they’re often fearful of ‘over-doing’ it, while some people are fearful of ‘failing’ and actually do over-do it! If a testing protocol is used, training and re-calibrating the humans doing the testing is needed. Otherwise it’s tempting for some clinicians to be drawn into pain behaviours and vary the test instructions or omit the test.
I’m not entirely sure that it’s inevitable for people with chronic pain to be technically ‘unfit’ – in fact, some of the people I’ve been working with are very fit with one chap being a keen skier, so probably far fitter than I am! Once again, I ask why it’s something we need to test – what if some of the clinicians were tested? However, it’s a common test and can give a baseline measure.
- Manual handling activities – these are frequently part of our physical performance set of tests. The aspects of performance that can be observed are things like activity planning, avoidance of certain movements (or loads), speed and confidence of movements, and the load tolerated. The same reliability factors as I’ve noted above in the walking tests apply here. Standard instructions, standard responses to questions from the patient, standard heights and weights and characteristics of the box – and my usual worry about predictive validity all apply.
- Hand function tests – for individuals with upper limb and hand pain, things like the Jebson Hand Function Test (from waaaaay back in the dark ages), grip strength testing and so on can be used for people with upper limb and upper back pain. I favour the Jebson because it attempts to replicate and standardise normal activities, and yes, there are norms available – but (broken record here!) it’s so important to ensure the clinicians using these tests carry them out according to protocol.
As you can see, there are so many assessments available, but some of the fundamentals of measurement science are lost when they’re translated into clinical practice.
Does this matter? Well, yes actually. I’ll say it again – there’s not a lot of point in assessing physical performance if it can’t be repeated in the same way each time. There’s even less point in assessing physical performance if it doesn’t represent or tap into something in the real world. Having said this, physical performance testing is the best time to really observe how the person responds to doing real world activities. It’s the best time to watch for pain behaviour, to elicit thoughts and beliefs about pain and movements, and to determine someone’s confidence to move.
Fellow functional clinicians – we have work to do! We need to learn more about the movements that people with pain find difficult in their daily lives. We then need to ascertain the constructs that we want to measure – and ensure these are being adequately captured in our physical performance tests. We then need to work out how to ensure consistent and reliable testing procedures, and finally, we might be able to put together a set of functional assessments that can be used to establish the functional problems a person has, why they’re having this trouble, and whether change has occurred after treatment.
I think it’s high time the connections between (usually) psychological constructs such as kinesiophobia (relatively easy) and values (not quite so easy) were related to physical performance – after all, our aim is to help people do more in their lives, isn’t it? And if we can’t test improvement, we can’t reliably inform those that pay for our services of the benefits of our interventions.
Oh yes – more will be coming on this topic! And yes, I’ll write about how we can put together these findings.