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CDC (2016): Methods of applying the 1994 case definition of chronic fatigue syndrome

Discussion in 'Latest ME/CFS Research' started by Kati, Mar 15, 2016.

  1. Kati

    Kati Patient in training

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    Popul Health Metr. 2016 Mar 12;14:5. doi: 10.1186/s12963-016-0077-1. eCollection 2016.
    Methods of applying the 1994 case definition of chronic fatigue syndrome - impact on classification and observed illness characteristics.
    Unger ER1, Lin JM1, Tian H1, Gurbaxani BM1, Boneva RS1, Jones JF1.
    Author information
    • 1Division of High-Consequence Pathogens and Pathology, National Center for Emerging and Zoonotic Infections, Centers for Disease Control and Prevention, 1600 Clifton Road, MS G41, Atlanta, GA 30329 USA.
    Abstract
    BACKGROUND:
    Multiple case definitions are in use to identify chronic fatigue syndrome (CFS). Even when using the same definition, methods used to apply definitional criteria may affect results. The Centers for Disease Control and Prevention (CDC) conducted two population-based studies estimating CFS prevalence using the 1994 case definition; one relied on direct questions for criteria of fatigue, functional impairment and symptoms (1997 Wichita; Method 1), and the other used subscale score thresholds of standardized questionnaires for criteria (2004 Georgia; Method 2). Compared to previous reports the 2004 CFS prevalence estimate was higher, raising questions about whether changes in the method of operationalizing affected this and illness characteristics.

    METHODS:
    The follow-up of the Georgia cohort allowed direct comparison of both methods of applying the 1994 case definition. Of 1961 participants (53 % of eligible) who completed the detailed telephone interview, 919 (47 %) were eligible for and 751 (81 %) underwent clinical evaluation including medical/psychiatric evaluations. Data from the 499 individuals with complete data and without exclusionary conditions was available for this analysis.

    RESULTS:
    A total of 86 participants were classified as CFS by one or both methods; 44 cases identified by both methods, 15 only identified by Method 1, and 27 only identified by Method 2 (Kappa 0.63; 95 % confidence interval [CI]: 0.53, 0.73 and concordance 91.59 %). The CFS group identified by both methods were more fatigued, had worse functioning, and more symptoms than those identified by only one method. Moderate to severe depression was noted in only one individual who was classified as CFS by both methods. When comparing the CFS groups identified by only one method, those only identified by Method 2 were either similar to or more severely affected in fatigue, function, and symptoms than those only identified by Method 1.

    CONCLUSIONS:
    The two methods demonstrated substantial concordance. While Method 2 classified more participants as CFS, there was no indication that they were less severely ill or more depressed. The classification differences do not fully explain the prevalence increase noted in the 2004 Georgia study. Use of standardized instruments for the major CFS domains provides advantages for disease stratification and comparing CFS patients to other illnesses.

    http://www.ncbi.nlm.nih.gov/pubmed/26973437
     
    Last edited: Mar 15, 2016
  2. duncan

    duncan Senior Member

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    Unger.

    Added: Isn't she part of the "admissions" process for who gets accepted into the NIH study?
     
    Last edited: Mar 15, 2016
  3. medfeb

    medfeb Senior Member

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    Yes
     
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  4. Scarecrow

    Scarecrow Annie Gsampel

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  5. anciendaze

    anciendaze Senior Member

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    Any evidence in this that the CDC has discovered PEM/PENE?
     
    green_monster and duncan like this.
  6. Kati

    Kati Patient in training

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    This begs the questions...(in no particular order)
    - what exactly is happening at CDC?
    - what ressources are used in validating ancient tools and cohorts and what meaning does it have in 2016?
    - what assets/conflict of interest is CDC protecting?
    - should Fukuda case definition be further studied following IOM and P2P reports?
    - what are CDC's priorities in terms of finding causes and cure for ME?
    - was this paper absolutely necessary in moving forward, in the 2016 context where millions of patients are waiting for medical care, diagnostics and treatments for ME?
     
    leela, Gemini, Justin30 and 9 others like this.
  7. duncan

    duncan Senior Member

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    ...- will she employ the Wichita or Georgia questionnaire to help qualify patients who can be allowed into the NIH study? Seeing as how they demonstrate substantial concordance....
     
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  8. geraldt52

    geraldt52 Senior Member

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    Shuffling paper? I wouldn't expect anything more. Although, I'm sure everyone involved has probably calculated their retirement benefits, and how many unused sick days they can use to retire early, at least once today.
     
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  9. Scarecrow

    Scarecrow Annie Gsampel

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    I thought it would be useful to provide a link to the forms used in what this study refers to as the 2004 Georgia method (aka 2004 Reeves aka empirical criteria).

    Can't promise that they are the best examples - if you know of better ones, please tag me and I'll update this post.

    Medical Outcomes Study: 36-Item Short Form Survey Instrument (SF-36)
    https://www.rand.org/health/surveys_tools/mos/mos_core_36item_survey.html
    this is an automated version of the form:
    http://www.sf-36.org/demos/SF-36.html


    Multidimensional Fatigue Inventory (MFI-20)
    http://link.springer.com/chapter/10.1007/978-1-4419-9893-4_57#page-1

    CDC Symptom Inventory for CFS
    http://www.institutferran.org/documentos/cdc_full_symptom_inventory.pdf


    The MFI link may not work but it's a relatively short form so I've recreated it below.
     
    Last edited: Mar 15, 2016
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  10. duncan

    duncan Senior Member

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    There is a three part admission process to the NIH study, if I recall.

    First, six clinicians, perhaps half of which seem to advocate a version of GET, which one can infer means up to three might not fully understand PEM - so maybe they shouldn't be submitting candidates.

    Second, Lipkin and Unger. Based on this new study, is everyone ok with Unger being able to distinguish sufferers of CFS from individuals with the symptoms of CF and/or depression?

    Third, three professionals who seem to lean toward psychogenic explanations of CFS.

    Each of the three steps has potentially built-in concerns.

    So, my comfort zone for the NIH populating its CFS study strictly with well-qualified CFS patients just got significantly smaller.
     
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  11. anciendaze

    anciendaze Senior Member

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    I'm not sure this has much bearing on the NIH study, we won't find out until decisions are pretty well fixed. What I believe this does is show "see, we were right all along, and we didn't just piss money away." Interpreted as defending the organization it makes sense. Patients? What do they have to do with anything important?
     
  12. duncan

    duncan Senior Member

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    See, I think it is a poignant reminder that it is federal employees or subcontractors who will be providing governance for the NIH study, and some of those people may be bringing unwanted baggage.

    Governments around the world have not exactly been the friend of the ME/CFS community, at least not historically.
     
    Last edited: Mar 15, 2016
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  13. daisybell

    daisybell Senior Member

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    Some interesting facts in this study for me -
    PEM is clearly identified as important
    Only one person with CFS was also depressed
    There is clear evidence of the need to exclude other conditions - otherwise over diagnosis is a significant factor
    The incidence seems to be increasing...
     
  14. Scarecrow

    Scarecrow Annie Gsampel

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    I found the write up unclear with respect to how depression / major depressive disorders were excluded for this study.
    In the method, they say:
    This suggests that anyone with a Zung score of >60 would have been excluded. The Fukuda case definition on the CDC site notes that "major depressive disorder with psychotic or melancholic features" [my emphasis] is exclusionary for CFS. Presumably, the person in this study who they classified under both methods as having CFS and also depression did not have psychotic or melancholic features. Who knows?
     
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  15. A.B.

    A.B. Senior Member

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    @Dolphin there is a typo: "I am not sure why did should be such a large difference in a cohort ..."

    Good job on the comment by the way.
     
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  16. jimells

    jimells Senior Member

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    I'm sooo glad that the CDC five million dollar line item in last summer's budget document was restored, so that CDC can continue to pump out useless studies that nobody in the world cares about. :bang-head:

    Meanwhile we are still waiting to see *something* from the CDC multi-site study.
     
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  17. duncan

    duncan Senior Member

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    Will the CDC release findings from the multi-site study BEFORE the NIH study is off the ground?

    Is there reason for them not to?
     
  18. medfeb

    medfeb Senior Member

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    Unless I am missing something, the prevalence of PEM seems very high.

    Reeves 2005 reported a prevalence of 2.54% which is about 6.2M adults in the US. This study said about 80% of the patients had PEM which translates to about 5M patients. Granted that PEM alone is not enough to diagnose the disease but still this is a much higher prevalence than I would have expected based on the most commonly accepted prevalence of about 1M U.S. patients.

    I assume the presence of PEM was based on the CDC Symptom Questionairre which I don't think is a good operationalization of PEM. But not sure if that is it.
     
    Last edited: Mar 16, 2016
  19. Dolphin

    Dolphin Senior Member

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    I have been one of the biggest critics of the empiric criteria (Reeves et al 2005). One of the big problems is one could qualify as having CFS even if one had no physical functioning impairments e.g. scored 100 out of 100 on the SF 36 physical functioning subscale. One could qualify as being disabled if one was impaired due to emotional reasons alone.


    Interestingly in this study, such a scenario arose in no cases:


    This means one can be more confident that the patients are genuine CFS patients.
     
    Last edited: Mar 15, 2016
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  20. Dolphin

    Dolphin Senior Member

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    I dislike the way the CDC interpret the phrase

    from

    The point of this phrase was so that if people were overworking or over exercising, they might appear fatigued but really if they rested a bit, they would get back to normal.

    What they did for their population studies such as Wichita 1997 was:

    aka

    I think this could exclude some people with genuine ME/CFS.
     
    Last edited: Mar 15, 2016

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