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Jason: Data mining: comparing the empiric CFS to the Canadian ME/CFS case definition.

Discussion in 'Latest ME/CFS Research' started by CBS, Aug 9, 2011.

  1. CBS

    CBS Senior Member

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    Another nice addition to Jason's body of work.He first showed that the "Empiric Definition" (Reeves, 2005) had led to a 10 fold increase in the diagnosis of CFS (creating a much more heterogeneous patient group that was originally diagnosed using the Holmes criteria). However, the question remained, was the Reeves criteria capturing more ME/CFS patients (in addition to more depressed patients)? Did the "Empiric Definition" have any redeeming qualities. This study answers that question with a resounding NO.

    Even thought the "Empiric Definition" was based upon the Fukuda criteria, it fails to properly identify as many ME/CFS patients (79%) as the Canadian Case Definition (87%). The "Empiric Definition" is neither the most specific nor the most sensitive diagnostic criteria for ME/CFS.


    Data mining: comparing the empiric CFS to the Canadian ME/CFS case definition.

    [FONT=&quot]Jason LA, Skendrovic B, Furst J, Brown A, Weng A, Bronikowski C.[/FONT]
    [FONT=&quot]
    [/FONT]

    [FONT=&quot]J Clin Psychol.[/FONT] 2011 Aug 5. doi: 10.1002/jclp.20827. [Epub ahead of print]

     
  2. CBS

    CBS Senior Member

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    More from the article:

     
  3. RustyJ

    RustyJ Contaminated Cell Line 'RustyJ'

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    Thanks for posting.
     
  4. Dolphin

    Dolphin Senior Member

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    Petition against the "empiric" criteria

    Thanks CBS. You've summarised it well. This is a fairly short paper with most of the text just explaining the patients, etc.

    Yes, here's what they say on this:
    The figures for each should be read in this context.

    There's a petition against the "empiric" criteria at:
    http://www.ipetitions.com/petition/empirical_defn_and_cfs_research/index.html which anyone can sign (one can also "like" it by clicking the button on that page).

    There is various information on other studies on the site esp. in the blog: http://www.ipetitions.com/petition/empirical_defn_and_cfs_research/blog
     
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  5. Firestormm

    Firestormm

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    Thanks for posting more of the study than I could get access to.

    I will read more thoroughly of what is there when I am less 'foggy' but one question if I may?

    Reeves identified 79% and Canadian 87% of an already establish cohort of patients. Established by Fukuda (CDC) upon which Reeves is based. Right, got that.

    Erhm... what about the 21% and 13% respectively, of patients that neither criteria identified? I mean I know this is not looking at actual patients or anything, and it could just be me at this point in my fogginess, but neither method is very accurate is it? I mean it is suggesting (still) that even the same criteria re-applied cannot produce the same results.

    I don't see that it can even be said that Canadian reveals 'purer' subjects either. Not based on this study. Can it?

    Anyway - as I hypothesised before when posting these results on another thread - this would appear to be what Jason has been working on then. It remains to see if the 'International' ME version will produce an even 'purer' and less subjective set of results I guess...
     
  6. Dolphin

    Dolphin Senior Member

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    I don't really understand the mathematics/similar involved but some observations:

    - The Fukuda criteria in this study is taken as the gold standard as that was how the patients were diagnosed in the study - however, that might not be best gold standard.

    - When one normally thinks of such issues, one thinks of sensitivity and specificity, however this may involve a different concept:
    - The point about the sort of patients a definition includes/construct validity is based on the important nodes, as far as I can see. The important nodes for the diagnosis were more ME-CFS like for the Canadian criteria than for the empiric criteria.
     
  7. oceanblue

    oceanblue Guest

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    I'm a bit nonplussed by this particular paper.

    It compares the ability of Canadian and Empiric criteria to diagnose patients with a confirmed Fukuda CFS diagnosis; it finds that the Canadian criteria diagnose more patients than the Empiric critria, and concludes that the Canadian crtieria are more effective. I'm surprised by the finding.

    First, the Empric criteria are essentially Fukuda with lax criteria, so I would have expected the Empiric criteria to diagnose 100% of the Fukuda patients, as opposed to the 79% found in this study. Possibly this is because Fukuda requires 4/8 symptoms, while Empiric also requires a minimum score based on frequency and severity of symptoms.

    Second, as the Canadian criteria are usually seen as more specific, I would have expected them to diagnose fewer Fukuda patients, while this study found 89% of Fukuda patients met the Canadian Critria. This contrasts with the recent large Nacul study (n=270, vs n=24 for this one) which found only 53% of Fukuda patients met the Canadian criteria.

    What would have been intersting would be to see how the Canadian and Empiric criteria compared when dealing with the 80 fatigued patients in this study who had had a Fukuda CFS diagnoses ruled out. I would have expected the Canadian criteria to be very good at excluding these non-CFS patients and the Empiric criteria to be poor at excluding them. However, this paper gives no data on these non-CFS patients.

    I did email Lenny Jason, who says he will be presenting data on this at a later date, and is actively collecting data on a larger group of patients. It looks like what we have here is work in progress, and the final data will hopefully be more revealing.

    This looks important, (as Dolphin & CBS highlighted):
    This feels like good evidence - and the most interesting part of the paper - but I'm not clear if this is a recognised way of validating case definitions.
     
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  8. Dolphin

    Dolphin Senior Member

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    Firstly, small error, I think the figure you have in mind is 87%.

    I think you may not be comparing like with like (with regard to the Nacul study). I think (not 100%) that the percentage may relate to the sum of the cases and non-cases of CFS - put them through the algorithm and see what percentage of the total are classified "correctly" as CFS cases or non-CFS cases as they case may be.
    Not 100% sure of this.

    It is novel to me and perhaps it does not have too much validity except as a pointer. It may be a bit like using a different statistically method of analysing data.
     
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  9. oceanblue

    oceanblue Guest

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    I asked Lenny about this and it seems the figure of 87% refers to 87% of CFS cases correctly identified and says nothing about diagnostic accuracy for non-cases.
     
  10. Snow Leopard

    Snow Leopard Hibernating

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    Maybe this shows that the Empiric criteria is not merely a lax version of the Fukuda criteria and that is why it lacks sensitivity as well as specificity?
     
  11. Firestormm

    Firestormm

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    Thanks Ocean. And presumably the same applies to the other percentile quoted.

    I must read the whole paper. Will move it back up the old list of priorities :)
     
  12. oceanblue

    oceanblue Guest

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    Yes, that's possible. It's worth noting that the Empiric criteria are based on the 2003 Ambiguities paper (basically updated Fukuda), the same definition used to diagnose CFS in this study. The empiric criteria uses odd ways of measuring fatigue and activity which Lenny Jason has elegantly shown leads to poor specificity. Maybe the Empricic's method of requiring a minimum symptom severity/frequency score leads to poor sensitivity too - I'd be interested in hearing more about this possibility. Or maybe the Empiric's fatigue/activity measures lead normal CFS patients being excluded but I don't really understand how that would happen, given how lax they are. It is all a bit puzzling.
     
  13. Firestormm

    Firestormm

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    Hadn't it previously been suggested (by Jason I think) that the CCC effectively reduces the number of patients diagnosed with CFS by the CDC criteria by a third?

    I have this figure in my head for some reason and can't for the life of me remember the actual context now...
     
  14. Dolphin

    Dolphin Senior Member

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    I think people are thinking of it as just applying the full definitions in a different format but using the exact same questions that would lead to the exact same percentages of sensitivity and specificity. However, I presume what was done was not that. That may explain the differences.
     
  15. WillowJ

    WillowJ คภภเє ɠรค๓թєl

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    Mary Schweitzer says the Empiric criteria is actually derived from the Oxford criteria (she says the surveys used were derived from SW's questionnaires)
     
  16. Firestormm

    Firestormm

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    Interesting perhaps to compare Jason's methods and results with this study in England that concluded:

    'The estimated minimum prevalence rate of ME/CFS was 0.2% for cases meeting any of the study case definitions, 0.19% for the CDC-1994 definition, 0.11% for the Canadian definition and 0.03% for the ECD. The overall estimated minimal yearly incidence was 0.015%. The highest rates were found in London and the lowest in East Yorkshire. All cases conforming to the Canadian criteria also met the CDC-1994 criteria but presented higher prevalence and severity of symptoms.'

    http://www.ncbi.nlm.nih.gov/pubmed/21794183 July 28 2011
     

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