Choline on the Brain? A Guide to Choline in Chronic Fatigue Syndrome
http://phoenixrising.me/research-2/the-brain-in-chronic-fatigue-syndrome-mecfs/choline-on-the-brain-a-guide-to-choline-in-chronic-fatigue-syndrome-by-cort-johnson-aug-2005
Discuss the article on the Forums.

Longitudinal mediation in PACE RCT of rehabilitative treatments for CFS: modelling & design conside

Discussion in 'Latest ME/CFS Research' started by Dolphin, Nov 19, 2015.

  1. Dolphin

    Dolphin Senior Member

    Messages:
    10,709
    Likes:
    28,270
    Free full text: http://www.trialsjournal.com/content/16/S2/O43

     
    Woolie likes this.
  2. Dolphin

    Dolphin Senior Member

    Messages:
    10,709
    Likes:
    28,270
    Physical function refers to the SF-36 physical function scores.

    It's not that surprising that changing fear avoidance might change how people report their impairments.

    The SF-36 physical function questionnaires asks whether you are limited regarding certain activities. The possible responses are: "Yes, limited a lot"; "Yes, limited a little"; "No, not limited at all". Change people's perceptions of what they feel they need to avoid and you'll change how they respond to questionnaires asking about their limitations.
     
    Sam Carter, Kati, Woolie and 4 others like this.
  3. A.B.

    A.B. Senior Member

    Messages:
    3,750
    Likes:
    23,195
    46% and 53% of 0% is still 0%.

    On a more serious note, I'm interested in the statistical analysis which supposedly provides insight into causality. That one can deduce causality alone in a PACE trial like setting sounds hard to believe. I'm guessing they're playing word games as usual.
     
    Last edited: Nov 19, 2015
    Sam Carter, Kati, Woolie and 7 others like this.
  4. Esther12

    Esther12 Senior Member

    Messages:
    8,449
    Likes:
    28,523
    First report on PACE mediation:


    http://www.trialsjournal.com/content/12/S1/A144

    Second:

    http://www.thelancet.com/journals/lanpsy/article/PIIS2215-0366(14)00069-8/fulltext

    Now the third:

    I won't be happy til they get above 50% for CBT too. Surely they can find a way?!
     
    Sam Carter, Woolie, Sean and 3 others like this.
  5. user9876

    user9876 Senior Member

    Messages:
    2,584
    Likes:
    18,187
    Given it didn't make it into their main paper I assume the results didn't support the hypothesis. The idea of throwing ever more complex stats at poor data is somewhat strange.

    This could be interesting "Autoregressive models accounting for measurement error" I've not seem anything they have done exploring measurement error and I don't see how an auto-regressive model would help since the biggest measurement error is because the measurement system is influenced differently by different treatment arms. I've never seen any discussion of error distributions from them or errors due to non-linearities in questionnaire based scales.

    The previous mediator paper made some fundamental in ignoring possible temporal relationships between mediator and endpoints or initial variables. Also I would wonder about independence of variables.

    Of course with no detail hard to say anything,

    This statement feels very worrying
    More flexible in that could be manipulated towards the hypothesis that they believe in "plausible'
     
    Sam Carter, Woolie, Sean and 2 others like this.
  6. Bob

    Bob

    Messages:
    9,872
    Likes:
    34,219
    England (south coast)
    The previous mediation analysis (which failed to demonstrate any mediation effects despite them concluding that they had demonstrated mediation effects) said that there would be another (longitudinal) mediation analysis.

    It looks like they have managed to increase the (purported) fear-avoidance mediation effect for both CBT and GET for physical function in the new abstract. I can't understand how they could have an increased the mediation effects using the same data, in this analysis, so look out for creative statistical methods, and smoke, and mirrors.
     
    Last edited: Nov 20, 2015
    Sam Carter, Woolie, leela and 5 others like this.
  7. Bob

    Bob

    Messages:
    9,872
    Likes:
    34,219
    England (south coast)
    Last edited: Dec 8, 2015
    Sam Carter, Woolie and Esther12 like this.
  8. leela

    leela Slow But Hopeful

    Messages:
    3,222
    Likes:
    7,234
    Couchland, USA
    Sam Carter and Woolie like this.
  9. Snow Leopard

    Snow Leopard Hibernating

    Messages:
    4,616
    Likes:
    12,462
    South Australia
    Looking at the data 3 different times and getting 3 different results. *shrugs*

    I agree, that is the most likely explanation. To truly claim there is less fear avoidance, there needs to be objective evidence that the patients actually did more stuff.
     
    Sam Carter, leela, Valentijn and 3 others like this.
  10. user9876

    user9876 Senior Member

    Messages:
    2,584
    Likes:
    18,187
    Really we need to look at the exact questions and how their semantics link and how they may correlate. To refer to a set of questions as a 'scale showing x' can be very misleading.
     
    Sam Carter, leela, Valentijn and 2 others like this.
  11. Daisymay

    Daisymay Senior Member

    Messages:
    740
    Likes:
    4,037
    I'm useless as statistics but if I may just reiterate the obvious, as well as exposing the statistical and methodological problems with PACE, they need to be challenged on the fact that patients are not saying they are fearful of exercise due to irrational, illogical wrong illness beliefs as is assumed n PACE, people are justifiably unhappy at/not prepared to/fearful of exercising beyond their own personal capabilities as they know from past experience it will lead to an exacerbation of their symptoms which may last for days, weeks, months. Patients reluctance to exercise beyond their capabilities is indeed a rational and logical response to a serious physical disease where post exertional malaise is a defining, and objectively verifiable symptom.
     
    MeSci, Snow Leopard, MEMum and 5 others like this.
  12. Bob

    Bob

    Messages:
    9,872
    Likes:
    34,219
    England (south coast)
    For Reference - Details from Previous Mediation Analysis

    It's all academic because there were no proven mediation effects in the previous paper and, as someone said 50% of zero is still zero. But, for reference, the (purported) fear-avoidance mediation effects from the previous paper were as follows...

    Fatigue

    CBT vs SMC 17%
    CBT vs APT 34%

    GET vs SMC 33%
    GET vs APT 61%

    Physical Function

    CBT vs SMC 27%
    CBT vs APT 37%

    GET vs SMC 43%
    GET vs APT 51%
     
    Last edited: Dec 8, 2015
  13. Dolphin

    Dolphin Senior Member

    Messages:
    10,709
    Likes:
    28,270
    I previously tried to find out which questions made up the fear avoidance questionnaire.
    http://forums.phoenixrising.me/inde...alysis-of-pace-trial.34927/page-2#post-545617

    ----

    Here are the questions for the Cognitive Behavioural Responses Questionnaire (CBRQ).

    The text says:
    Appendix says:
    I'll try to mark the ones that are definitely or possibly part of a scale - the definite ones are underlined. I have a PhD thesis that looked at them but it used four cognitive factors rather than five (it didn't have "damage beliefs). It had the first 11 as fear avoidance when there are only 6 of them (I think many of them are damage beliefs). It also had the next 6 questions [i.e. "I worry that I may become permanently bedridden because of my symptoms" to "I will never feel right again"] as catastrophising while there is only supposed to be 4 (although figures in the Appendix only add to 40 questions while there are 42 questions so the 6 questions may all be catastrophising].

    --------------
    Two behavioural measures: all-or-nothing behaviour and avoidance or resting behaviour. I believe these last 13 questions are them

     
  14. Dolphin

    Dolphin Senior Member

    Messages:
    10,709
    Likes:
    28,270
    Here's the SF-36 physical functioning subscale. You score 0 for each "Yes, limited a lot"; 5 for each "Yes, limited a little"; and 10 for each "No, not limited at all".

     
    Snow Leopard and MEMum like this.
  15. Snow Leopard

    Snow Leopard Hibernating

    Messages:
    4,616
    Likes:
    12,462
    South Australia
    It is important to note that a change on the SF-36 PF score of 10, is either one question changed from limited a lot to not limited at all, or two questions moving half a step from limited a lot to limited a little, or from limited a little to not at all.

    How meaningful is this level of change really?
     
    Sam Carter, SOC and Valentijn like this.
  16. Sean

    Sean Senior Member

    Messages:
    3,260
    Likes:
    18,001
    This is a core issue that PACE has to be confronted on, the serious disconnect between their abstract number waving and extravagant sales pitch, and the actual practical real world benefits to patients of those numbers, which is basically none.
     
    Sam Carter, leela, SOC and 4 others like this.
  17. Kati

    Kati Patient in training

    Messages:
    5,466
    Likes:
    19,610
    You know, the PACE trial will be retracted and this group of so-called scientists will still write and publish papers.

    And the band played on.
     
  18. MeSci

    MeSci ME/CFS since 1995; activity level 6?

    Messages:
    7,985
    Likes:
    12,847
    Cornwall, UK
    Is it just me, or does the last sentence of the 'conclusions' make no (grammatical) sense at all?
    I don't know if it's brain fog, but I can't get my head round what they are trying to say here.
     
    Valentijn likes this.
  19. A.B.

    A.B. Senior Member

    Messages:
    3,750
    Likes:
    23,195
    They probably rushed this out of the door just to publish something and distract from the slowly sinking PACE trial (therefore typos).
     
    Valentijn likes this.
  20. Bob

    Bob

    Messages:
    9,872
    Likes:
    34,219
    England (south coast)
    My guess is that its supposed to mean: "Approximately half of the effect of each of CBT and GET were on physical function was mediated through reducing avoidance of fearful situations."

    I hear that fiction publishers are cutting back on proof-readers these days.
     

See more popular forum discussions.

Share This Page