Chronic Pain Assessment and Measurement


Ask anyone who has worked in chronic pain management for a while about assessment tools or measurement and you’ll see the eyes roll – how many assessment questionnaires do we need???

Firstly I want to clarify what I mean by assessment, and the difference between that and measurement.

Measurement is all about quantifying something – how much, how often, is there more of [x] than [y]? did [a] have an effect on [b]?

The problem in pain is that because pain is an individual, subjective, personal experience we can’t directly measure it. We have to extrapolate from something observable to something that can’t be seen. This means we are really measuring correlates of the pain experience rather than pain itself.

Pain assessment, on the other hand, is about learning more about the qualitative experience of pain.

In pain assessment, I am forming a ’rounded’ picture of the individual and the factors that may be associated with the experience, and hoping to answer the question I have of ‘why did this person present to me in this way on this occasion?’ I collect information over a range of domains including biophysical, psychological and social – and rely on other members of the team to help complete the picture through their assessments (I focus on psychosocial and functional).

What difference does it make?

  • Pain measurement is really helpful when trying to quantify improvement, difficulties, or to establish whether this person is more or less severely affected by their pain. Measurement is important when trying to determine whether an intervention has achieved anything (eg outcome measurement), or whether to provide a person with a certain type of treatment (eg will this person respond to anti-depressant medication?). Measurement on its own, however, won’t make any difference to your rapport, empathy or quality of your intervention. It won’t necessarily help you to understand where this person is coming from nor to prioritise your interventions.
  • Pain assessment should directly help you establish the beginning of a case formulation, or working hypotheses, about the factors that may be influencing this person’s presentation – and in doing so, should help you develop some understanding of how the problems have arisen, how they are affecting the individual, how they are being maintained, and what intervention priorities you may have.

What tools can you use for pain measurement and assessment?

Hmmmm! well there are literally 100’s of pen and paper and other measurement instruments in pain…where to start? Before I answer this, there are quite a few questions to ask yourself…

  • If you’re assessing an individual, you may not want to use any formal measurement tools – quite simply psychometric tests can’t provide you with anything more than what your patient/client is prepared to tell you. They are not X-rays of the mind! They simply organise information, may be a little more efficient at times than interview, and they should (if well-developed) be reliable (measure the same thing the same way each time they’re used), be valid (measure what they say they’re going to measure), and help you compare this person with other people who have taken the same questionnaire (provided the original group with whom you are comparing this person is somewhat similar to your client/person!).

In choosing questionnaires or measurement instruments, it’s important to ask yourself – what do I really want to find out? Why might I use a pen and paper tool when I could ask the question? What is the burden on the patient/client to fill out this questionnaire? Can I interpret it? What does it mean if I do interpret it? What does a certain score actually mean? Can it predict anything? I can use it as an outcome measure? How do I report the findings?

    Behavioural measures are not nearly as readily available, nor used, as pen and paper questionnaires. This is partly because they are time-consuming to do properly, and often involve recording the person using video or photographs, then reviewing and scoring. Training to complete behavioural measures accurately is essential to ensure inter-rater reliability (like calibrating any other measurement instrument!). The predictive validity of behavioural measures such as Functional Capacity Evaluations or Assessments has not been well-established, and it’s important to recognise that these measures are only an indication of what this person is prepared to do on this day, not ‘lie detectors’! There is no way to determine whether someone is ‘malingering’ or ‘faking’ or ‘symptom magnifying’ – and health providers should not allow themselves to try to make this type of determination, it probably belongs with investigators rather than in health.

    A great reference for assessments that may be used in pain, and including a wealth of information on concepts such as validity, reliability and so on is the Handbook of Pain Assessment (2nd Ed, 2001) Edited by DC Turk and R Melzack, published by The Guilford Press.
    This mighty tome contains 100’s of full versions of many of the assessment tools that have been used in pain and pain management. More importantly is the reference to the original articles for these tools. To be really ethical about using psychometric assessments and measures, it’s vital to read the original research, and subsequent published literature about the properties and normative data associated with the measure.

    I’ll write more about assessment and case formulation soon – keep coming back for more, or if you don’t want to miss, you can subscribe using the RSS feed above. If there is a specific assessment or measurement tool you’d like to learn more about, put it in the comments and I’ll do my best!

    3 comments

    1. Assessment of risk of drug abuse and addiction in patients who may be prescribed opioid analgesia is suggested in order to minimize subjective clinical decisions arising from preconceived notions and/or prejudices held by the practitioner. Screening tools are just that…an objective means of identifying those patients who may require further, in depth assessment of addiction or abuse. To simply rely on the patient’s self-report is gambling with the outcome. Addicts and drug sellers typically lie to obtain what they want; they excel at deception. Therapeutic decisions can’t be made based on patient appearance; the meth-addicted ‘Soccer Mom’ is a prime example. Use pain assessment tools to establish a pain baseline and a therapeutic goal. Use ORT or CAGE AID as a screener to determine the need for further assessment. Have a second professional assess the patient to ensure that the input is similar. If nothing else, should the patient turn out to be diverting or abusing drugs, documentation is in place to demonstrate that assessment was conducted.

    2. I understand what you mean with regard to the risks of opioid abuse and people with addictions who intentionally deceive to obtain medications. Our pain centre has a policy of not prescribing opioids on a first consultation – and all people who attend the Centre are assessed by three people (medical, psychosocial and functional). We have a written opioid policy that all of us abide by.

      If a person attends already taking an opioid or other drug of addiction (notably benzo’s), we work together with our Community Alcohol and Drug Addiction Centre to either reduce their use of them, or to transfer them to something less socially desireable or easily diverted.

      If the person is already known to the CADS Centre, they will be jointly managed by both of us.

      Pain intensity isn’t a good measure on which to determine whether a medication or any intervention has ‘worked’, it’s not objective (but then neither are any pain measurement tools), and it is subject to both deliberate and nondeliberate influence. eg if a person is distressed at the time of completing a VAS, the score is often higher (especially if they’re having a ‘bad’ day, and their last few days have been ‘bad’). If they are intending to obtain medication for drug abuse purposes,yes, they may report higher pain intensity.
      HOWEVER to suggest that there are objective measures of risk of abuse, is to probably over-state the case – screening tools are only as good as what the person is prepared to tell you.

      I totally endorse using multiple measures prior to prescribing any intervention (medication or otherwise), and to identify the functional goal the person is aiming for – it’s simply not enough to say ‘I want my pain reduced by 50%’. We would ask ‘What difference will having your pain reduced by 50% make in terms of your activity? How can we measure this?’, and if the functional goal isn’t achieved, the medication or intervention needs to be reviewed and (usually) stopped.

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