Each time I spend listening to someone who is really finding it hard to cope with his or her pain, I hear the unspoken cry that pain has taken over everything. It can be heartbreaking to hear someone talk about their troubled sleep, poor concentration, difficult relationships, losing their job and ending up feeling out of control and at the mercy of the grim slave-driver we call chronic pain. The impact of pain can be all-pervasive, and it can be hard to work out what the key problems are.
To help break the areas down a little, I’ve been quite arbitrary really. I’m going to explore functional limitations in terms of the following:
1. Movement changes such as mobility (walking), manual handling, personal activities of daily living
2. Disability – participation in usual activities and roles such as grocery shopping, household management, parenting, relationships/intimacy/communication
3. Sleep – because it is such a common problem in pain
4. Work disability – mainly because this is such a complex area
5. Quality of life measures
The two following areas are ones I’ll discuss in a day or so – they’re associated with disability because they mediate the pain experience and disability…as I mentioned yesterday, they’re the ‘suffering’ component of the Loeser ‘rings’ model.
6. Affective impact – things like anxiety, fear, mood, anger that are influenced by thoughts and beliefs about pain and directly influence behaviour
7. Beliefs and attitudes– these mediate behaviour often through mood, but can directly influence behaviour also (especially treatment seeking)
There are so many other areas that could be included as well, but these are some that I think are important.
Before I discuss specific instruments, I want to spend yet more time looking at who and how – and the factors that may influence the usefulness of any assessment measure.
Who should assess these areas? Well, it’s not perhaps who ‘should’ but how can these areas be assessed in a clinical setting.
Most clinicians working in pain management (doctors, psychologists, occupational therapists, physiotherapists, nurses, social workers – have I missed anyone?) will want to know about these areas of disability but will interpret findings in slightly different ways, and perhaps assess by focusing on different aspects of these areas.
As I pointed out yesterday, there are many confounding factors when we start to look at pain assessment, and these need to be borne in mind throughout the assessment process.
How can the functional impact of pain be assessed?
- Self report, eg interview, questionnaires – and the limitations of these approaches are reliability, validity threats as well as ‘motivation’ or expectancies
- Observation, either in a ‘natural’ setting such as home or work, or a clinical setting
- Functional testing, again either in a ‘natural’ setting such as home or work, or a clinical setting – and functional testing can include naturalistic procedures such as the AMPS assessment, formal and structured testing such as the 6 minute walk test, the sock test, or even certain functional capacity tests; or it may be clinical testing such as manual muscle testing or range of movement, or even Waddell’s signs
All self report measures, whether they’re verbal questions, interview or pen and paper measures are subject to the problem that they are simply the individual’s own perception of the degree of interference they attribute to pain. The accuracy of this perception can be called into question especially if the person hasn’t carried out a particular activity recently, but in the end, it is the person’s perception of their abilities.
All measures need to be evaluated in terms of their reliability and validity – how much can we depend on this measure to (1) assess current status (2) contribute to a useful diagnosis (or formulation) (3) provide a basis for treatment decisions (4) evaluate or measure function over time (Dworkin & Sherman, 2001).
Reliability refers to how consistently a measure performs over time, person, clinician.
Validity refers to how well a test actually measures what it says its measuring. The best way to determine validity is if there is a ‘gold standard’ against which the test can be compared – of course in pain and functional performance, this is not easy, because there is no gold standard! The closest we can come to is a comparison between, for example, a self report in a clinic on a pen and paper test compared with a naturalistic observation in a person’s home or workplace – when they’re not being observed.
Probably one of the best chapters discussing these aspects of pain assessment is Chapter 32, written by Dworkin & Sherman chapter in the 2nd Edition of the Handbook of Pain Assessment 2001 (DC Turk & R Melzack, Eds), The Guilford Press.
Importantly for clinicians working in New Zealand, or outside of North America and the UK, the reference group against which the client’s performance is being compared, needs to be somewhat similar to the population the client comes from. Unfortunately, there are very few assessment instruments that have normative data derived from a New Zealand or Australasian population – and we simply don’t know whether the people seeking treatment in New Zealand are the same on many dimensions as those in North America.
I’m also interested in how well any instruments, whether pen and paper, observation or performance-based assessment translate into the everyday context of the person. This is a critical aspect of pain assessment validity that hasn’t really been examined well. For example, the predictive validity (which is what I’m talking about) of functional capacity tests such as Isernhagen, Blankenship or other systems have never been satisfactorily established, despite the extensive reliance on these tests by insurers.
Observation is almost always included in disability assessment. The main problems with observation are:
– there are relatively few formal observation assessments available for routine clinical use
– they do take time to carry out
– maintaining inter-rater reliability over time can be difficult (while people may initially maintain a high level of integrity with the original assessment process, it’s common to ‘drift’ over time, and ‘recalibration’ is rarely carried out)
While it’s tempting to think that observation, and even functional testing, is more ‘objective’ than self report, it’s also important to consider that these are tests of what a person will do rather than what a person can do (performance rather than capacity). As a result, these tests can’t be considered infallible or completely reliable indicators of actual performance in another setting or over a different time period.
Influences on observation or performance-based assessments include:
– the person’s beliefs about the purpose of the test
– the person’s beliefs about his or her pain (for example, the meaning of it such as hurt = harm, and whether they believe they can cope with fluctuations of intensity)
– the time of day, previous activities
– past experience of the testing process
And of course, all the usual validity and reliability issues.
More on this tomorrow, in the meantime you really can’t go far past the 2nd Edition of the Handbook of Pain Assessment 2001 (DC Turk & R Melzack, Eds), The Guilford Press.
Here’s a review of the book when the 2nd Edition was published. And it’s still relevant.