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"What makes a difference in chronic fatigue syndrome?": Commentary on PACE Trial mediators paper

Discussion in 'Latest ME/CFS Research' started by Dolphin, Jan 13, 2015.

  1. Dolphin

    Dolphin Senior Member

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    (Note: There are two other threads on the PACE Trial mediators paper itself here: http://forums.phoenixrising.me/inde...ndary-mediation-analysis-of-pace-trial.34927/ and here: http://forums.phoenixrising.me/index.php?threads/new-pace-paper-more-smc-spin.34924/)

    This is also free if one signs in: http://www.thelancet.com/journals/lanpsy/article/PIIS2215-0366(14)00145-X/abstract

    Note: these two psychologists are big CBT fans/promoters.
     
    Last edited: Jan 16, 2015
  2. Dolphin

    Dolphin Senior Member

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    Most objective measures showed no difference in the PACE Trial. One that did was the 6-minute walking test distance for GET (but not for CBT) which showed a small improvement although the results were still very poor for people of a mean age of 39 (esp. as people with lots of other chronic illnesses couldn't take part).

    However, Knoop and Wiborg think that may be simply because the GET patients pushed themselves a little harder:

     
    Last edited: Jan 13, 2015
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  3. anciendaze

    anciendaze Senior Member

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    Remember, we are talking about an increase of about 40 meters out of hundreds. This would not count as clinically significant even if we were talking about patients with a serious problem like heart failure, where change is notably difficult.

    Also note that about 1/3 of the patients did not participate in the six-minute walk both before and after a year of treatment. I suspect that the original values were simply carried forward for those patients who did not take the second test. This is equivalent to stipulating that no patient suffered a setback, one of the hypotheses allegedly under test. Since the criteria for adverse events were changed during the study, to make it harder to register an adverse event, PACE provided absolutely no assurances about possible setbacks caused by GET beyond the observation that nobody died.

    If the effect of GET was simply that patients with a fixed energy budget who were tired after a session declined the walk test, while those with a larger energy budget participated, this could produce the reported results without any deep psychological interpretation. The effort required to participate in therapy would simply do a better job of separating sheep from goats.

    A change of some 20 meters in the distance of the group considered a control either means that similar modest improvement takes place without treatment, or that the one objective measurement left in the study was not properly controlled for test/retest familiarization.

    The result was about as meaningless as it is possible to get, yet this has had no impact on researchers ability to spin hypotheses.
     
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  4. biophile

    biophile Places I'd rather be.

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    [​IMG]
     
    Last edited: Jan 14, 2015
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  5. biophile

    biophile Places I'd rather be.

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    Why do they keep talking about the importance of increasing activity levels when their own research disputes the notion that CBT/GET increases (multiple objective measures of) activity levels? Haha @ "an increase in physical activity is nothing more than a catalyst". If it doesn't or never happens how can it be a catalyst for anything? IIRC in previous papers they speculate about undetected increases in physical activity in the earlier stages of therapy which later get converted to social activities.
     
    Last edited: Jan 14, 2015
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  6. Sean

    Sean Senior Member

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    Just bizarre, isn't it.
     
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  7. Sidereal

    Sidereal Senior Member

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    It wasn't last observation carried forward. They just assumed that data were missing at random and carried out a completer analysis.

    "did not differ greatly"

    How about presenting the maximum likelihood analyses so we can judge for ourselves?
     
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  8. Simon

    Simon

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    Would this analysis cover the scenario where people didn't complete the tests because they were unable/felt ill, where it would have been reasonable to assume their performance would be worse than average? That would seem to be key here.
     
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  9. Sidereal

    Sidereal Senior Member

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    Well, in that case, data would not be missing at random which is an incredibly difficult problem to deal with.
     
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  10. Simon

    Simon

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    Cause or effect?

    At the heart of the mediation approach is showing a sequence of events, where the treatment afffects the mediator first, then the mediator affects the outcome. This appearst to be the case in this study, where mediators change first (12 weeks, or 24 for 6MWT) followed by an improved outcome at 52 weeks.

    Treatment => Mediator => Outcome

    Except, the outcomes improve at 12 and 24 weeks too. In other words, judging by figure 3 in this paper and the outcomes in the original PACE trial, 'mediators' and outcomes improve together. It may be that as people become less fatigued/able to do more, the 'mediator beliefs' change as a consequence. I'm not sure this study is able to show which happens first: the outcomes of fatigue and function may be changing the 'beliefs', not the other way around. Or the two may happen in tandem.

    Added to this, the study says that the relationship between meditiators and outcomes were the same in all treatment groups, ie including APT and SMC, where beliefs and behaviours were not challenged.
     
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  11. A.B.

    A.B. Senior Member

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    They really don't seem to care anymore. It's just spin, spin, spin.
     
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  12. anciendaze

    anciendaze Senior Member

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    Again, this is tantamount to ignoring either the possibility that any patient for whom data were missing suffered a setback, or that patients were using energy from a fixed budget to participate, as has been found in both patient reports and other studies.

    Both alternatives amount to assuming something which was supposed to be a result of this study. If I am allowed to assume results, when convenient, I can produce some really astonishing research.
     
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  13. Dolphin

    Dolphin Senior Member

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    One will recall that in the PACE Trial's cost effectiveness paper
    http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0040808 , they said
    when in fact valuing care at the minimum wage rate (one of the sensitivity analyses mentioned in the paper) made a huge difference (and valuing it at 0 which was a sensitivity analysis in their statistical plan made an even bigger difference).
     
    Last edited: Jan 14, 2015
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  14. Bob

    Bob

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    This might have been posted before, but I'm catching up...
    Here's an interesting extract from the Knoop and Wiborg commentary...
    They seem to be acknowledging that CBT in general fails to change the illness itself, and fails to improve disability, but that it only changes interpretation of symptoms or the patients' perception of the illness. That's probably a big thing if you consider CFS to be psychosomatic, but it's an interesting observation nonetheless.
     
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  15. Valentijn

    Valentijn Senior Member

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    Or they're suggesting that there's no disability in the first place, despite all evidence to the contrary. No reduction in movement means no need to improve.
     
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  16. Dolphin

    Dolphin Senior Member

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  17. Dolphin

    Dolphin Senior Member

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    Although they can't really say that there is no reduction in movement when their own studies have found lower than average movement, both before and after treatment.
     
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  18. Valentijn

    Valentijn Senior Member

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    Yes, I think that's why they're not being completely specific and are just saying things which might imply several things to their audience. I think they're counting on readers to interpret it to mean that there's no disability to start with - after all, it wouldn't make sense for someone to say that reports of fatigue are more important than actual disability!
     
  19. Bob

    Bob

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    I understand what you're getting at Val, but I can't see how they can deny that there is a disability, considering that all of their research demonstrates that there is a severe problem with physical function, physical capacity and physical disability etc. I think perhaps they might dismiss disability as unimportant because it is a indicator of illness beliefs rather than an indicator of an actual physical illness. But I'm not over familiar with the work of Knoop and Wiborg, so I don't really know what their stance is.
     
  20. Valentijn

    Valentijn Senior Member

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    They did the Dutch Nijmegen studies where they later revealed that actometers showed no improvement. They spun that as meaning that activity levels weren't important in reducing fatigue.
     
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