May 12, 2017 Is International ME/CFS and FM Awareness Day
International ME/CFS and FM Awareness Day is May 12th, 2017. Jody Smith shares some information about upcoming events and ways you can be heard ...
Discuss the article on the Forums.

Study findings challenge the content validity of the Canadian Consensus Criteria for adolescent CFS

Discussion in 'Latest ME/CFS Research' started by A.B., Feb 3, 2015.

  1. A.B.

    A.B. Senior Member

    Messages:
    3,751
    Likes:
    23,188
    Study findings challenge the content validity of the Canadian Consensus Criteria for adolescent chronic fatigue syndrome


    I have not read the article since it's behind a paywall. Could anyone with access tell us a bit more?
     
  2. Valentijn

    Valentijn Senior Member

    Messages:
    14,281
    Likes:
    45,811
  3. Valentijn

    Valentijn Senior Member

    Messages:
    14,281
    Likes:
    45,811
    barbc56 and Esther12 like this.
  4. Simon

    Simon

    Messages:
    1,919
    Likes:
    14,452
    Monmouth, UK
    Study findings challenge the content validity of the Canadian Consensus Criteria for adolescent chronic fatigue syndrome
    - see above for absract & conclusion that CCC patients no different from CFS ones.

    Nice idea, shame about the execution

    The basic idea of this study is pretty interesting. Take a bunch of broadly defined CFS patients, select from that group those that meet the much tighter Canadian Consensus Criteria, and see if these CCC patients differ on a range of objective measures from the non-CCC patients.

    The authors found no significant difference between the two groups (pretty minor cognitive one) and concluded the CCC do not select a group of patients who are different from generic any-definition-will-do CFS patients.

    Personally, I think the ability to select patients with different biological characteristics IS a key test any worthwhile case definition must pass. Unfortunately, it seems this test wasn't up to much, because they way they defined CCC is highly suspect - using a questionnaire of their own making without any input from the CCC group.

    How ALL patients were defined:
    Seems fine as broad CFS definitions go

    How CCC patients were defined
    This is where it goes wrong
    Note they don't have any severity score (Leonard Jason has done a lot of work showing how important it is to assess severity as well as frequency of symptoms - ignoring severity makes the criteria far too lax). And they only looked at symmptoms for the last month, not six months or more.

    Iā€™m not sure the authors of the CCC, or case definition experts such as Leonard Jason, would consider a 1991 paper by Michael Sharpe and colleagues (21) a sound basis for diagnosing patients according to the 2003 CCC.

    edit: As Dolphin points out, the paper quotes the wrong reference and so their questionnaire is NOT based on Michael Sharpe's 1991 paper, but on their version of the CCC ME/CFS diagnositc worksheet. However, as I argue below, this questionnaire is still unvalidated and doesn't look up to the job of accurately diagnosing Canadian criteria ME/CFS (not enough symptoms and ignoring symptom severity).


    To recap, the authors diagnosed CCC using an unvalidated questionnaire based on a 1991 symptom list from Michael Sharpe and colleagues, ignored symptom severity and only considered symptoms over the last month. That doesn't really cut it, so I'm not sure the results of this study tell us very much at all.

    However, this is how the authors interpret their study:
    Per Fink, for the record.
     
    Last edited: Mar 20, 2015
  5. Esther12

    Esther12 Senior Member

    Messages:
    8,449
    Likes:
    28,522
    Thanks for looking into that Simon.

    My question from just a lazy look at the abstract was: Do they have any evidence that patients who fulfil their loose criteria differ significantly from patients with an even looser criteria (BSS/FSS amd beyond)? Or on to sedentary controls? What value did the measures used have in diagnosing other CFS criteria? Couldn't these sorts of studies be used to justify a steady expansion of criteria until they covered everyone?
     
    oceiv, Dolphin and barbc56 like this.
  6. Dolphin

    Dolphin Senior Member

    Messages:
    10,670
    Likes:
    28,172
    I'd say the 21 is a typo and they meant 20.

    They used reference 21 correctly earlier
    Sometimes references get added or subtracted with various revisions before submission and again during peer-review. I notice it not infrequently.
     
    Valentijn likes this.
  7. Dolphin

    Dolphin Senior Member

    Messages:
    10,670
    Likes:
    28,172
    To test the hypothesis the way they did, I think they needed to show that what was tested showed different results to healthy controls.

    If one tests for something that was not different in the patients than in healthy controls, it is not going to be that surprising if one doesn't find differences between different groups of CFS patients. Unfortunately cytokines don't tend to be reliably different in ME/CFS patients than healthies. For example, Hornig et al. (2015) tended to find differences between those ill three years or less and those ill longer, but few differences when these groups were pooled together and compared to healthies.
     
  8. Dolphin

    Dolphin Senior Member

    Messages:
    10,670
    Likes:
    28,172
    One difference between the groups that isn't mentioned in the abstract is step count

     
    Last edited: Mar 18, 2015
    Valentijn, Sidereal and oceiv like this.
  9. Dolphin

    Dolphin Senior Member

    Messages:
    10,670
    Likes:
    28,172
    There were two findings that were close to being statistically significant:

    ----

    This is potentially a bit interesting. One might expect the more ill group (those who satisfied the Canadian Clinical Criteria, with lower step counts and more symptoms) to have more mood disorders. In fact, the opposite was the case. This suggests the possibility that the Non-Canadian Clinical Criteria group contains some people who don't have ME/CFS/SEID at all and instead might have a primary mood disorder (or at least have a group that are a bit different).

    Here are the overall entry criteria again:
     
    Valentijn, oceiv and Denise like this.
  10. SOC

    SOC

    Messages:
    7,802
    Likes:
    16,462
    I'm a bit puzzled. Do I understand correctly that they claimed to confirm no psychiatric disorder that might explain fatigue as a requirement for entry, but then found symptoms suggesting a mood disorder in nearly half of the non-CCC group?
     
  11. Dolphin

    Dolphin Senior Member

    Messages:
    10,670
    Likes:
    28,172
    They found symptoms suggesting mood disorder in 48% of CCC patients and 65% of non-CCC patients. However, one can have a mood disorder secondary to being ill.
     
  12. SOC

    SOC

    Messages:
    7,802
    Likes:
    16,462
    Ah, of course! Still, I'm not sure how they distinguished whether the patients had a primary psychiatric condition presenting as fatigue or a secondary mood disorder as the result of chronic illness. It would take some very careful evaluation, I think, to be reasonably confident of that differential diagnosis. I doubt they did that careful evaluation and consequently let in quite a few primary psych patients.

    It's interesting, if the mood disorders are thought to be secondary to chronic illness, that more non-CCC patients showed symptoms of mood disorder than CCC patients. I wonder how that could be interpreted. No doubt there are multiple plausible explanations. :)
     
  13. Simon

    Simon

    Messages:
    1,919
    Likes:
    14,452
    Monmouth, UK
    Might have been the way I wrote it up :)
    [QUOTE"I said they"]This study had some limitations. The questionnaire items used to subgroup CFS patients have not been formally validated for this purpose. However, they correspond closely to the ME/CFS clinical diagnostic worksheet (21 - Sharpe et al).[/QUOTE]I meant ref 21 was the Sharpe questionnaire they used to diagnose accoriding to Carrduthers/Canadian (20). And my point was that an unvalidated 1991 questionnaire is not fit for diagnosing according to 2003 CCC (which is very much a tool for clinicians). This is a study making judgements about the validity of diffferent case definitions: if you don't make a decent fist of the case definition implementation, it becomes a pointless exercise. Certainly it's not suitable methodology to back up this claim that they went on to make:
    As you say, they might be right about no cytokine difference, but I don't think this study provides the evidence to back up this claim.
     
  14. Dolphin

    Dolphin Senior Member

    Messages:
    10,670
    Likes:
    28,172
    My point is that I don't think they used something comparable to a 1991 questionnaire (Sharpe et al., 1991). The 1991 paper doesn't have a big long set of questions comparable to the Canadian criteria - if they had used the 1991 paper as a basis a large percentage of the Canadian criteria symptoms wouldn't have been asked about. (One can see the 1991 paper here: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1293107/)

    I think they used their own questionnaire which is asks a lot of questions and they think can be used to try to access who would satisfy the 2003 Canadian criteria

    i.e. this sentence should have said reference 20 not 21.
     
    Last edited: Mar 20, 2015
    Simon likes this.
  15. Simon

    Simon

    Messages:
    1,919
    Likes:
    14,452
    Monmouth, UK
    Thanks, see what you mean about their own questionnaire, not Sharpe's:
    However, this still looks like an inadequate way to assess CCC ME/CFS - which goes to the heart of what the paper is doing:
    1. They used 24 common symptoms (we don't know which ones), compared to over 50 listed in the ME/CFS diagnostic worksheet
    2. That worksheet is appendix 5 of the CCC paper - appendix 3 is another worksheet, this time focusiing on symptom severity, which CCC stresses is important in making diagnoses: this current paper does not assess severity
    3. Their questionnaire has not been validated as they acknowledge.
    4. It's all very different from Lenny Jason's work with this 100+ item DePaul Symptom questionnaire, which places a lot of emphasis on symptom severity, and has been psychometrically validated (well, as much as any questionnaire has been)
    So the situation is better than I'd orginally posted (will update) but falls a long way short of diagnosis that is good enough to make the claim that all forms of CFS are the same (and part of bodily distress syndrome).
     
    aimossy and Dolphin like this.
  16. waiting

    waiting Senior Member

    Messages:
    449
    Likes:
    866
    Steps per day - number, mean (SD)

    Canadian Clinical Criteria group 3958 (2142)

    Non-Canadian Clinical Criteria group 5144 (2482)

    p value=0.006

    @Dolphin, does this mean that the 1st number is the average actual steps/day -- over how long of a period? And so what does the bracketed number mean? I can't recall how to interpret standard deviation....
    Thanks!
     
  17. Dolphin

    Dolphin Senior Member

    Messages:
    10,670
    Likes:
    28,172
    Yes, average steps per day.
    Details:
    Standard deviations give an idea of the variety of scores, whether they are all clustered close to the mean or spread out wide on both sides of a mean.

    If data is normally distributed, 68% of scores will be between "mean - 1 standard deviation" and "mean + 1 standard deviation".
     
  18. waiting

    waiting Senior Member

    Messages:
    449
    Likes:
    866
    Thank you for explaining that, and excuse me for being dense -- but does that mean the CCC group walked a average of 3958 steps/day? Then what does the 2142 represent for the CCC group?
    Thanks again.
     
  19. Dolphin

    Dolphin Senior Member

    Messages:
    10,670
    Likes:
    28,172
    Yes, the CCC group walked an average of 3958 steps/day.
    If the distribution is not normally distributed, it is not easy to interpret what the standard deviation means exactly. It just gives an idea of how close or otherwise the scores were on average to the mean i.e. 3958 steps.
     
    waiting likes this.
  20. waiting

    waiting Senior Member

    Messages:
    449
    Likes:
    866
    3958 steps per day seems very high for a group of ME patients.
     

See more popular forum discussions.

Share This Page