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Latent class analysis of a heterogeneous international sample of patients with myalgic encephalomyelitis/chronic fatigue syndrome (Leonard Jason team)

Discussion in 'BioMedical ME/CFS Research' started by Dolphin, Jul 4, 2018.

  1. Dolphin

    Dolphin Senior Member (Voting Rights)

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    https://www.tandfonline.com/doi/full/10.1080/21641846.2018.1494530

     
  2. strategist

    strategist Senior Member (Voting Rights)

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  3. MeSci

    MeSci Senior Member (Voting Rights)

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    I found this wording questionable: "feeling hot/cold for no reason". I'm sure there is a reason! I get very hot after doing an activity for a while, and suspect that it's due to my delayed adjustment mechanisms. It stops after I've stopped the activity for about 5 minutes.
     
  4. Inara

    Inara Senior Member (Voting Rights)

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    What's the gain of this 6-subclass-category? And I didn't understand the symptom selection criteria for building these classes. Does someone?
     
  5. Sly Saint

    Sly Saint Senior Member (Voting Rights)

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    I haven't read the full paper but do they note duration of illness anywhere?; in my experience you can develop 'new' symptoms and older symptoms can decline in severity as time goes on (possibly due to better management).
    So I don't think this approach to sub-sets particularly helpful.
     
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  6. Trish

    Trish Moderator Staff Member

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    I've just read through the paper and am dubious about the whole enterprise. I don't criticise the effort or the intention, which I am sure is good, but I find it odd that they don't seem to take duration or current severity of illness into account as an important and possibly confounding factors to the whole enterprise. Unless I've missed something, which is entirely possible.

    For example, as my illness has declined through mild and moderate to fairly severe, I've acquired extra symptoms along the way and some have become more severe. But I'm still the same person with the same illness... Hmm. Not sure.
     
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  7. Tom Kindlon

    Tom Kindlon Senior Member (Voting Rights)

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  8. Dolphin

    Dolphin Senior Member (Voting Rights)

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    I'm not sure how valuable this study is, like Trish, but now I have read it, I might as well post observations.
     
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  9. Dolphin

    Dolphin Senior Member (Voting Rights)

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    So people who had the symptom some of the time were included with those who had it none of the time.
     
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  10. Dolphin

    Dolphin Senior Member (Voting Rights)

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    I don't understand the details but the authors had different options to choose from. The one they chose wasn't the best on all measures.
     
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  11. Dolphin

    Dolphin Senior Member (Voting Rights)

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    This is the main table. The numbers are the probabilities somebody from a particular class had the symptom (using the 2/2 threshold)

    Huber 2018 table 3.png
     
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  12. Dolphin

    Dolphin Senior Member (Voting Rights)

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    I have to wonder with at least some these particular symptoms, how accurately people are reporting them.

    People could concentrate on some symptoms more than others.

    For example, I remember being more conscious of my heartbeat previously but now I don't pay much attention to it so might say that I don't have an irregular heartbeat, particularly after having normal ECGs.

    This could be particularly important if people concentrate on particular types of symptoms.

    I avoid standing as much as possible, so don't have as much dizziness as previously.
     
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  13. Dolphin

    Dolphin Senior Member (Voting Rights)

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  14. Dolphin

    Dolphin Senior Member (Voting Rights)

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    This seems a common enough finding: the more severe an illness people have, the more symptoms they have.

    It was interesting previously when Jason did previous studies where people were divided by severity. There was a difference on virtually every symptom. I think in general summing the scores of all the symptoms could be useful to define severity thresholds or even as illness criteria, but Jason seems to avoid wanting to do that.
     
  15. Dolphin

    Dolphin Senior Member (Voting Rights)

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    This might put them at odds with supporters of the international consensus criteria, for example.

    I think the authors of this study might need to give more specific details to justify this claim e.g. Are these specific symptoms used in a problematic way in other criteria?
     
    Last edited: Aug 25, 2018
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  16. Dolphin

    Dolphin Senior Member (Voting Rights)

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  17. Dolphin

    Dolphin Senior Member (Voting Rights)

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    They do later on go on to say that the classes need to be replicated, so I suppose this is not totally unreasonable. But for the moment, it might be simpler just to treat people by their individual symptoms rather than these speculative classes.

    The point with regard to subgrouping research samples may be stronger.

     
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  18. Dolphin

    Dolphin Senior Member (Voting Rights)

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    It is a little interesting to see the dynamics of applying for disability payments/benefits being discussed in a paper. And though I'm not 100% convinced by all their arguments about prejudice or difficulties, perhaps empirical evidence might show it to be true.

    Certainly it seems plausible that somebody with a "relapsing and remitting" illness course might find it more difficult to get disability payments (or alternatively they might be less likely to see the process of applying through, either by not applying at all, or by giving up if they faced difficulties if they then had a good period).

    They could have looked at the variable involving a "relapsing and remitting" illness course directly to see if the relationship was stronger or weaker, rather than doing solely relying on the class method.
     
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  19. Dolphin

    Dolphin Senior Member (Voting Rights)

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  20. Dolphin

    Dolphin Senior Member (Voting Rights)

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