It might work, but does it work in the manner you think it does? Another good talk at the American Pain Society meeting in Honolulu.

There are not too many conferences now in which I don’t get the question over tea and biscuits about whether or not I believe in this therapy or that. I find it an intriguing question and one I usually answer with ‘Well, not in the same way I believe in gravity or in the fundamental worth of each human’.  From the look on the face of the questioner, I suspect I have missed their point. One might paraphrase the question by asking whether or not I think these therapies ‘work’. I reckon that the question often comes from a place of knowing, deep in their belly, that the therapy works for them and being confronted by an RCT or two that suggest it works a bit but not any better than this other therapy. I might say in response ‘well, let’s say it works – the question I find more interesting then, is why does it work?’

We sometimes have some pretty whacky mechanisms to explain treatments that work and I am on the record as saying that we need to be open-minded about how an apparently effective treatment might work. Well, it seems that the psychology world is dealing with the same issues.  Dr John Burns has just given us his US$5 dollars worth and has argued that we have to stop doing more trials and dump the waiting list control thing and for all these mechanism-like statements we need to prove it.

To conceptualise what this means, one might state that a cognitive intervention reduces pain by reducing pain related catastrophising. Burns proposes a list of 5 criteria that must be satisfied if we are to uphold this kind of statement. Because ‘mechanism’ is terrifically difficult to measure in behavioural research (indeed the radical behaviourists clearly state that they have no interest in mechanism – only in observables), we will talk about ‘mediator’ instead.

So, to conclude that a treatment is effective because of a particular mediator, we need:

1. Change in the proposed mediator correlates with change in the outcome.  If the cognitive intervention reduces pain by reducing catastrophising argument, decreased PCS score needs to correlate with decreased pain.

2. Change in the mediator precedes change in outcome. That is, decreased catastrophising occurs before the decrease in pain.

3. Early change in the mediator predicts later change in outcome but not the other way around. That is, early decrease in catastrophising predicts later decrease in pain but early decrease in pain does not predict later decrease in catastrophising.

4. Change in the mediator is specific to the treatment. That is, the control group does not show a decrease in catastrophising.

5. The relationship between change in the mediator and change in the outcome is not observed across treatments.  That is, the temporal pattern of change in catastrophising and change in pain should not be observed in the control group.

Clearly, to answer these questions we will need to take serial measures – pre and post just won’t do.

As I was listening, I thought this is good stuff indeed – and most of the research in physical and psychosocial interventions for chronic pain don’t do this. Then I thought I had better think about this with my own views on my own research. Let’s start then, with Explaining Pain (EP). The theory behind explaining pain is that it decreases pain by changing the underlying schema about what pain actually is.  Does this mechanism statement satisfy the Burns list?

1. Change in the proposed mediator correlates with change in the outcome.  YES. Change in pain correlates with change in pain biology knowledge as measured by the pain knowledge questionnaire (PKQ).

2. Change in the mediator precedes change in outcome. YES. Change in PKQ can occur in hours but change in pain takes weeks to months. The exception to this is seen in a paper from Euro J Pain [1] in which changes in pain threshold were observed immediately. So, that experiment may not satisfy this rule but it may be because we didn’t have enough measurements over time.

3. Early change in the mediator predicts later change in outcome but not the other way around. YES. Increase in pain-related knowledge directly after a 3 hour Explain Pain predicts pain reduction 3 weeks and 6 months later.

4. Change in the mediator is specific to the treatment. YES, In the research we have done, even when we compare EP plus CBT to CBT alone, change in PKQ occurs in the EP group but not the control group.

5. The relationship between change in the mediator and change in the outcome is not observed across treatments.  YES. We sometimes see a change in PKQ after a change in pain in the better control treatments (eg CBT).

So, EP satisfies the Burns test, which suggests that a change in pain-related biology knowledge contributes to the effect of EP on pain reduction.

About Lorimer Moseley

grey It might work, but does it work in the manner you think it does? Another good talk at the American Pain Society meeting in Honolulu.Lorimer is NHMRC Senior Research Fellow with twenty years clinical experience working with people in pain. After spending some time as a Nuffield Medical Research Fellow at Oxford University he returned to Australia in 2009 to take up an NHMRC Senior Research Fellowship at Neuroscience Research Australia (NeuRA). In 2011, he was appointed Professor of Clinical Neurosciences & the Inaugural Chair in Physiotherapy at the University of South Australia, Adelaide. He runs the Body in Mind research groups. He is the only Clinical Scientist to have knocked over a water tank tower in Outback Australia.

Link to Lorimer’s published research hereDownloadable PDFs here.

Reference

[1] Moseley GL (2004). Evidence for a direct relationship between cognitive and physical change during an education intervention in people with chronic low back pain. European journal of pain, 8 (1), 39-45 PMID: 14690673

Comments

  1. John Quintner says:

    What relationship, if any, does the lived experience of pain bear to pain-related catastrophizing (whatever that may be)? Could there have been a category mistake here? Please help me out here if I seem to be missing the point.

  2. Lorimer, just reading the Graded Motor Imagery book and recalling our meeting just before you talked in Philadelphia a while back. You signed my Explain Pain book and asked what I do. I briefly explained my decade of specializing in chronic pelvic pain and that we are now incorporating EP into our program. You welcomed me to the “revolution”. I am looking forward to your talk to the International Pelvic Pain Society in Chicago later this year and hope you urge a lot more thinking in this group of practitioners about “Why approaches to chronic pain work or don’t work”. We are still barraged with tons of patients that have had so many invasive procedures and still have the “worst pain ever”. Thanks for all you and NOI do…. Dr. E

    John Quintner Reply:

    Robert, a truly “burning” question. Would you agree to rephrase your “…approaches to chronic pain …” with approaches to the patient with chronic pain”? A small change but an important one, in my opinion. We do not treat a “thing” called pain!

  3. Peggy Heinselman says:

    John, glad you asked the question. I seem to also be missing the point as well. Hope we get a clarification.

    John Quintner Reply:

    Peggy don’t hold your breath waiting for a reply. The theorists may have hit a brick wall (metaphorically) when they cannot tell us whether catastrophizing about one’s pain is a cause or an effect or simply a value judgment unilaterally imposed upon the sufferer by an objective observer (yes, I know this is an oxymoron).

    Frédéric Wellens,pht Reply:

    Mr Quintner,

    I’m interested in your question and the point you want to make. Could you expand further on it? I am, myself, always wondering about what the nature of the link between pain catastrophizing and or fear-avoidance measures and the pain experience itself.

    John Quintner Reply:

    I was hoping someone else would shed light on these questions. For what it is worth, in my view of the world, pain catastrophizing and fear avoidance are terms used by an observer who is attempting to put his or her interpretation on the lived experience of another human being. In the absence of a shared negotiation between them, these terms can become highly stigmatic labels for the person in pain. How often does this happen?

  4. John and Peggy, no need to “hold your breath”, Peggy, because I totally agree on changing my characterization to “approach to the individual with chronic pain”. Why even say “patient”? – value judgement in itself… I am not a seasoned blogger but I am a seasoned clinician and my interest in chronic pain as an entity, as opposed to “acute pain” as an entity is where the current educational focus should be in medical school and residency programs. The vast majority of care givers of all professions are still reacting to individuals’ expressions of pain as an entity that must be caused by some type of observable tissue damage and if that damage cannot be “observed” than it either doesn’t exist or it is all “in the head” (catastrophizing?). I have never used that word in 40 years of practice and it is abhorrent to me as a clinician taking care of “individuals” who are suffering. My readings of the explosion of science regarding “chronic” pain as an “entity” has been an interesting journey, and the transition I needed to make regarding “pain” as a diagnosis, rather than a symptom, was tortured. Understanding of the biology of chronic pain has been and remains a difficult barrier for most physicians and clinicians because it is still not being taught in medical schools and elsewhere even close to where the research has gone. The “tools” to do so have remarkably expanded and I marvel at the basic research. But my day to day challenge is to “translate” that research into human terms for the individuals who seek my help. “Explain Pain” and the concepts of “Graded Motor Imagery” have been a revelation to me as further “tools” to use “on the ground” with “patients” presenting commonly to me with “end stage” pelvic pain when they tell us they “wish they had cancer so that someone would listen to them and validate their condition and would make a plan to help them get their lives back”. I find myself negotiating away the term “pain signals” with them and more towards “danger signals” – which makes it greatly more understandable as to why their “neuromatrix” and “neurotags” ( whatever they are???) continue to protect them because the biological processes of their bodies are predetermined to do so. Understanding “chronic pain” as an entity then helps them understand more clearly how the neuroplastic nature of the nervous system can then be incrementally re-booted. It is incumbent upon health care providers to understand that we will all become “patients” at some point and that there is a great difference between “pain and suffering” and “illness and disease”. Bob

    John Quintner Reply:

    Robert, my learning experience mirrors yours. Why say patient? Because the word derives from the Latin patiens, which means sufferer. Some will argue that they do not suffer when they experience pain. I am loath to contradict them!

  5. Thanks a million folks for these excellent ponderings. I don’t know if anyone has thoughts about this more than you have John and I am clearly no expert on it. I agree that catastrophising lends itself to stigma – I have felt that stigma here of all places in response to my own ponderings on my own pain – but I am particularly interested in your caveat – that ‘in the absence of a shared negotation between (person in pain and clinician*), catastrophising and fear avoidance become highly stigmatic labels….’ Can you elaborate on that – I know your wisdom has sparked substantial interest and nods and perhaps a few shakes. So, if you would be generous enough to elaborate?
    * = i have filled in words to avoid having to go back to your quote. I am also intrigued as to whether ‘clinician’ is also a term ‘used by an observer who is attempting to put his or her interpretation on the lived experience of another human being’. If so, where should we draw the line? Will removing all observer-placed labels be better?

    John Quintner Reply:

    Thanks Lorimer for your words of encouragement. Yes, we clinicians are all observers, even of ourselves. We have indeed elaborated upon our ponderings in a recent article in the journal Pain Medicine – Cohen et al. Stigmatization of the person in pain: the negation of empathy. It can be downloaded from the website of Painaustralia (go to Health Care Profesionals and thence to Research) if you have not seen it. It is directed at clinicians and we hope provides food for thought in these difficult times of outcome-based funding. Value-based funding for health care does not even rate a mention.

    ian stevens Reply:

    http://www.chronicpainaustralia.org.au/files/downloads/Stigmatization%20paper%20-%20published%20version.pdf

    John , thanks for pointing me towards your paper (above).
    I found the implications discussed here to be of relevance….
    “The imparting to them of up-to-date neurobiological information is obviously important, but in our opinion, such programs need to first focus attention upon what is hap- pening in the intersubjective where health profes- sionals first engage with their patients. Without a sufficiently negotiated sense-making engagement in this “third space,” any education may all too readily default to an imposition of the beliefs and attitudes of the clinician upon the sufferer.”
    I found this to be extremely important – perhaps easy to dismiss without due reflection ?
    Pain management in practice often seems to be a series of often pointless task orientated events .. (6 sessions of ‘acupuncture’,’blocks’,handing out of machines etc ) rather than an interactive attempt at mutual understanding or an attempt at a shared experience.?
    Perhaps pain management needs to consider some of the insights by Dr Cahana here ? http://www.iasp-pain.org/AM/AMTemplate.cfm?Section=HOME&TEMPLATE=/CM/ContentDisplay.cfm&SECTION=HOME&CONTENTID=7621
    Personally , the neurobiological understanding is both fascinating and important but often the ‘intersubjecive space’ may benefit from additional understanding gained from other areas of life perhaps (‘humanities’ for example)?
    With regards to this the British Pain Society have run annual meetings on various topics relating to pain and suffering under the umbrella of philosophy and ethics (the transcripts available here –the 2008 one with Dr Cahana is particularly good ) http://www.britishpainsociety.org/members_sigs_philosophy.htm
    However , working and thinking like this is often difficult , particularly for long periods of time and this needs due consideration too?
    Thanks again for the paper and your other ‘iconoclastic’ ones!

    Ian