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Coyne demolishes Per Fink's trial of CBT for medically unexplained symptoms

Discussion in 'General ME/CFS News' started by A.B., Dec 7, 2016.

  1. A.B.

    A.B. Senior Member

    Danish RCT of cognitive behavior therapy for whatever ails your physician about you

    As usual Coyne is good at spotting problems:

    The authors also switched outcomes years after the trial began.
    Last edited: Dec 7, 2016
    mango, Woolie, Dolphin and 25 others like this.
  2. A.B.

    A.B. Senior Member

    This also sounded interesting to me, although I'm not sure I understand. @Woolie help please
  3. SilverbladeTE

    SilverbladeTE Senior Member

    Somewhere near Glasgow, Scotland
    Anywhere else that would be lambasted as fraud
    But hey, the Medical world has little if anything to do with Science.....
    PennyIA, Jan, taniaaust1 and 2 others like this.
  4. Dx Revision Watch

    Dx Revision Watch Suzy Chapman Owner of Dx Revision Watch

    There is an attribution issue with this commentary.

    In his blog at:

    under the heading "Detailed analysis" Prof Coyne has written:

    Professor Coyne has presented these extracts from Allen Frances' December 8, 2012 Psychology Today blog as though they had been authored by Allen Frances.

    This is not the case. It is quite clearly stated by Prof Frances at the beginning of his commentary that he is quoting at length from communications with me, Suzy Chapman of Dx Revision Watch.

    Yet Professor Coyne has chosen not to attribute the quotes he reproduces to me.

    Here is an extract from Coyne's source material taken from:

    Mislabeling Medical Illness As Mental Disorder

    Allen Frances MD, DSM 5 in Distress Blog at Psychology Today, December 8, 2012

    At the end of Prof Coyne's blog, he writes:

    "Special thanks to John Peters and to Skeptical Cat for their assistance with my writing this blog. However, I have sole responsibility for any excesses or distortions."

    As the person who has amassed a considerable body of work on the DSM-5 proposals since 2009, run a website dedicated to DSM-5 and ICD-11 development, raised awareness in 2010, 2011 and 2012 of the DSM-5 Review and Comment periods, encouraged hundreds of submissions during these public comment exercises on the SSD proposals, worked with journalists and co-authored several papers around SSD, it is interesting to note that Professor Coyne has chosen not to correctly attribute to me texts he uses to illustrate his analysis.

    I would take this up with Coyne via Twitter but I am amongst those whom he continues to keep blocked.

    Instead, I shall be asking Allen Frances if he will request that Coyne make the necessary corrections.
    Last edited: Dec 8, 2016
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  5. Dx Revision Watch

    Dx Revision Watch Suzy Chapman Owner of Dx Revision Watch

    The second link Coyne gives to an Allen Frances Psychology Today blog commentary is this one (one of a series of three we collaborated on for his Psychology Today blog around DSM-5 and SSD and to which I contributed content):

    Bad News: DSM 5 Refuses to Correct Somatic Symptom Disorder
    Medical illness will be mislabeled mental disorder
    Jan 16, 2013

    about which Coyne writes:

    In order to reach that point in Allen Frances' blog, Coyne would have read:

    Extraordinary then, the extent to which Coyne has grayed me out or "disappeared" me from these two commentaries on DSM-5's SSD.
    Last edited: Dec 8, 2016
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  6. Dx Revision Watch

    Dx Revision Watch Suzy Chapman Owner of Dx Revision Watch

    In response to Coyne's blog:

    Experts weigh in on Suzanne O’Sullivan’s commentary on imaginary illness in The Lancet
    April 30, 2016

    (in which he gave Edward Shorter a platform and promoted Shorter's book "From Paralysis To Fatigue" and promoted Shorter's blog) I submitted the following Comment on May 3:

    In his comments, Prof Ronald Pies draws attention to Allen Frances’ concerns for DSM-5’s new Somatic symptom disorder (SSD) category.

    For ease of reference, here is a list of papers and commentaries on SSD published by Allen Frances in collaboration with Suzy Chapman:

    which is still displaying as:

    "Your comment is awaiting moderation"
    mermaid, Roy S, actup and 4 others like this.
  7. JohntheJack

    JohntheJack Senior Member

    Swansea, UK
    Perhaps you could contact Prof Coyne through the blog and point this out.
  8. Dx Revision Watch

    Dx Revision Watch Suzy Chapman Owner of Dx Revision Watch

    Given the nature of responses meted out to at least three advocates known well to me, I am reluctant to have direct contact with Coyne.
    Webdog, Roy S, actup and 2 others like this.
  9. Dx Revision Watch

    Dx Revision Watch Suzy Chapman Owner of Dx Revision Watch

    I would contact PLOS, but my understanding is they don't have editorial control over the blogs that are hosted on the PLOS platform.
    actup and trishrhymes like this.
  10. trishrhymes

    trishrhymes Senior Member

    @Dx Revision Watch - Maybe someone else could comment on your behalf. I'll have a go if you want me to, just tell me what to say!
    actup, Wildcat and slysaint like this.
  11. Dx Revision Watch

    Dx Revision Watch Suzy Chapman Owner of Dx Revision Watch

    Since the Coyne PLOS blog discusses the Fink et al BDS construct and also touches on DSM-5's SSD, I thought I would collate four key documents in this thread for reference, now that they are all public domain.

    (I may also open a new thread for this important issue.)

    (1) Bodily distress disorder in ICD-11: problems and prospects
    Oye Gureje, GM Reed, Sept 2016 Open access

    This is the most recent report from the ICD-11 Somatic Distress and Dissociative Disorders Working Group (S3DWG), which, among other tasks, has been asked to propose revisions to the Somatoform disorders categories in ICD-10.

    This external working group is chaired by Oye Gureje. Frances Creed* is a member. I have the names of a couple of other members but the full S3DWG membership list is not in the public domain.

    The paper published in September describes the proposals for the "Bodily distress disorder" construct as defined and entered into the ICD-11 Beta draft.

    It is an SSD-like construct and SSD has been inserted in the Beta draft under "Synonyms" to "BDD" - as you can see here:

    There are three proposed severities: Mild; Moderate; Severe, and for each a Definition has been entered into the draft.

    As defined by ICD-11 core version, "BDD" shares all the problems inherent in DSM-5's Somatic symptom disorder.

    Furthermore, it proposes to use a term that is already being used in the field, interchangeably, for Fink et al's "BDS" construct, despite the fact that "BDS" is differently conceptualized, has different criteria and potentially captures different (though to an extent overlapping) patient groups.

    The divergence between the "BDS" construct and the "SSD" construct has been acknowledged by DSM-5's Dimsdale and by Fink, Creed and Henningsen.

    *Although Francis Creed was a member of the DSM-5 work group, he does not like the SSD construct or the name. He favours the BDS construct, although he is on the ICD-11 working group that is proposing an SSD-like construct. So it doesn't surprise if Creed is holding out for the term "Bodily distress disorder" as it is already often used for Fink's BDS.

    The PCCG group also proposes to use the term "Bodily Distress Disorders" but as a section header under which the categories "Bodily Stress Syndrome" and "Health anxiety" (which replaces "Hypochondriasis") would sit.


    (2) An alternative construct has been proposed by the (external) Primary Care Consultation Group (PCCG) for use in the ICD-11 PHC.

    The ICD-11 PHC is being developed in parallel with the core ICD-11 and is an abridged version of the Mental disorders chapter for use in Primary Care and low resource settings. It is expected to comprise 28 of the "most common" mental health disorders found in Primary Care.

    The PCCG is chaired by Prof Sir David Goldberg; the membership list is in the public domain.

    The PCCG's most recent paper is:

    Multiple somatic symptoms in primary care: A field study for ICD-11 PHC: WHO's revised classification of mental disorders in primary care settings
    David P. Goldberg, D.M., Geoffrey M. Reed, Ph.D. et al

    The Primary Care Consultation Group proposes to call its recommended construct "Bodily Stress Syndrome" (BSS), which, as already noted, would sit under a section heading, "Bodily Distress Disorders."

    Their initial proposed construct had been for a close adaptation of Fink et al's (2010) Bodily distress syndrome (BDS).

    From the most recent paper:

    "...The ICD-10 PHC [1] contained a category called ‘medically unexplained somatic complaints’, defined by negative physical investigations and frequent visits to the PCP despite these negative findings. The development of the ICD-11 PHC provided an opportunity to re-think this description, drawing in part on research conducted in Denmark by Fink and colleagues [7,8], including a recommendation that three or more symptoms was a useful threshold for primary care populations [9].Fink and his colleagues proposed a conceptualization of Bodily Distress Syndrome that emphasized the co-occurrence of symptoms falling into cardiopulmonary, musculoskeletal, and gastrointestinal clusters and explicitly linking these symptom clusters to ‘functional’ syndromes of non-cardiac chest pain, fibromyalgia, and irritable bowel syndrome. This conceptualization was subsequently expanded to include an additional cluster of ‘general’ symptoms (e.g., concentration difficulties,memory impairment, fatigue) theorized as corresponding to chronic fatigue syndrome [7,9]. Support for the notion that apparently distinct collections of somatic symptoms are united by underlying common features has been provided by a number of empirical studies [10–19]."
    The most recent paper states:

    "As a concept, BSS brings together under a common rubric allegedly
    different patterns of symptoms variously described as constituting
    different ‘functional’ syndromes (e.g., fibromyalgia, irritable bowel syndrome)."​

    Within the proposed criteria for the Primary Care Consultation Group's proposed "BSS", there is no listing of "Chronic fatigue syndrome" under "Exclusion" or "Differential diagnosis", see Page 86-87 Appendix 2 [1].

    The original proposed "BSS" criteria, based on symptom clusters from body systems, and closely adapted from Fink et al (2012) and are set out in Appendix 2 (Pages 86-87) of the Lam et al paper in reference [1] at the end of this report.

    In the most recent paper it says:

    "The version of the Bodily Stress Syndrome diagnosis used in this
    study was adapted for use in primary care settings from the proposed
    diagnosis of Bodily Distress Disorder proposed for the main ICD-11
    [24] by creating a specific cutoff of at least three symptoms not explained
    by no known medical pathology that were associated with distress
    or impairment and eliminating the requirement that the PCP make
    a judgment about whether the attention devoted to the symptoms is
    ‘excessive’. Patients with fewer than three symptoms are very common
    in primary care setting. Our focus group study [6] had indicated that
    PCPs preferred a specific symptom cutoff point and were reluctant to
    make a judgment about the subjective degree of attention paid by the
    patient to the symptoms."​


    "One purpose of the present study was to examine the importance of
    the specific symptoms clusters emphasized by Fink and colleagues
    based on work in Denmark [7,8,9]. While clusters of cardiopulmonary,
    musculoskeletal, gastrointestinal, and ‘general’ symptoms can be identified
    in the current data, in the current clinical sample their significance
    for diagnosing BSS is less clear given that the most common symptom
    pattern was three or more symptoms in multiple clusters (57.9%;
    CI95% = 53.8–62.0) and the average number of somatic symptoms
    among this groupwasmore than 15, and nearly 11 in the overall sample
    (see Table 3). Only in China was single symptom cluster BSS the most
    common pattern (44.4%; CI95%=32.0–56.8). Therefore, for the ICD-11
    PHC description of BSS, the best course would seem to be to describe
    these common patterns but not to require that symptom presentations
    conform to them in assigning a diagnosis."​

    No psychobehavioural responses are required to meet the Fink "BDS" criteria. But for "BSS" there is a nod, potentially, towards BDD's and SSD's requirement for psychobehavioural responses.

    Note that like SSD, the core version's proposed "BDD" can be applied to any symptom(s) - if the clinician decides the response to the symptom(s) is "excessive". So that means BDD, like SSD, could be applied as an additional diagnosis to diagnosed cancer patients, coronary heart disease patients, patients with MS, diabetes, CFS, ME, IBS, FM etc.

    Whereas in the PCCG's "BSS" (in common with Fink's "BDS") - "If the symptoms are accounted for by a known physical disease this is not BSS." [1]

    ICD Revision expects there to be construct/disorder congruency between the disorders to be included in the Primary Care version and the corresponding disorders in the Core version and all this has been discussed with ICD Revision's, Dr Geoffrey Reed.

    Some time ago, I requested Exclusions for PVFS, BME and CFS under "BDD". Dr Reed has said that he cannot request Exclusions until the missing G93.3 legacy terms have been restored to the Beta draft, "but at such time, he would be happy to do so."

    Note: The recommendations of external work groups are advisory and approval of proposals is the responsibility of the Joint Task Force (JTF) and the ICD classification experts.

    ICD's Robert Jakob gave assurances, last June, that he can be “crystal clear” that there is no proposal or intention to classify the ICD-10 G93.3 legacy terms under the Mental and behavioural disorders chapter.

    Think of it as a continuum, with the "pure" Fink BDS on the far left, and the "pure" DSM-5 SSD on the far right:

    Operationalised BDS ---- proposed BSS ---- proposed BDD ---- published SSD

    Add to that the fact of the S3DWG's proposing to call its construct by the same name that is often seen used in the literature and in the field for "BDS" and you don't need me to spell out the scope for disorder creep and the potential difficulty for maintaining construct integrity within and beyond ICD-11; nor the implications for all patients.

    For an expansion on this see my document below (which was written before the two new papers were published):

    Comment submitted to TAG Mental Health in May re: Bodily distress disorder (May 2015)


    (3) Here is the 2013 MASTER PROTOCOL for the ICD-11 PHC field trials:

    MASTER PROTOCOL Depression, Anxiety and Somatic Symptoms in Global PC Settings: A Field Study for the ICD-11-PHC

    In the Lam et al (2013) paper, below, there is also discussion of the pilot field trials that took place in 2011 and the characterization and criteria, as were proposed in 2012, are set out in Appendix 2.

    1 Full free: Proposed new diagnoses of anxious depression and bodily stress syndrome in ICD-11-PHC: an international focus group study, Lam et al (2013) html

    [Edited to add extracts and other comment]
    Last edited: Dec 9, 2016
  12. Dx Revision Watch

    Dx Revision Watch Suzy Chapman Owner of Dx Revision Watch

    Note that in the ICD-11 Beta draft, IBS remains under

    Chapter: Diseases of the digestive system
    > Irritable bowel syndrome or certain specified functional bowel disorders
    >> Functional gastrointestinal disorders
    >>> Irritable bowel syndrome

    For ICD-11 Beta draft the most recent proposal for Fibromyalgia is to relocate under a new Chronic pain class:

    Chapter: Symptoms, signs or clinical findings, not elsewhere classified

    General symptoms, signs or clinical findings
    > Chronic pain
    >> Chronic primary pain
    >>> Mono-site primary chronic pains syndromes
    >>> Multi-site primary chronic pains syndromes
    Last edited: Dec 9, 2016
  13. Dx Revision Watch

    Dx Revision Watch Suzy Chapman Owner of Dx Revision Watch

    I'll open a new thread for ICD-11 later today.
  14. Dx Revision Watch

    Dx Revision Watch Suzy Chapman Owner of Dx Revision Watch

    In his PLOS blog, Coyne has written:

    A reminder that Dimsdale signed off on the new DSM-5 SSD criteria.

    He also refused to budge on a redraft of the criteria to tighten them up and reduce over diagnosis. It wasn't just the Task Force that rejected Allen Frances' redraft suggestions; they had also been rejected by Dimsdale.

    At the APA's Annual Conference in Philadelphia, in 2012, Dimsdale gave a slide presentation on the unpublished field trials for what, at that point, was proposed to be called "CSSD". (The new diagnosis for DSM-5 was subsequently named "SSD.")

    At the end of his presentation, Dr Dimsdale took a number of questions from the audience around proposals for CSSD and Conversion disorder.

    One questioner asked: Chronic fatigue syndrome has not been a part of the DSM-IV so far. Would there be any place for that in the DSM-5?

    Dr Dimsdale's response was: That's an important question. Chronic fatigue is an important, distressing, disabling condition - it is remarkably heterogeneous...remarkably heterogeneous. We feel that some patients with chronic fatigue would meet the criteria for CSSD - some wouldn't.

    The questioner responded: And what would be the cut off point...or what would be the criteria to include some and exclude others?

    Dr Dimsdale replied: Well, chronic fatigue is really almost a poster child for medically unexplained symptoms as a diagnosis - it's a very, very heterogeneous disorder and we would say that the B type criteria are defining. Now, I have friends with chronic fatigue - some of them would meet these criteria and some wouldn't - so if a person is unable to put this down or unable to get beyond the...who is just stuck with the B type considerations, we would consider that to be having CSSD.

    For testing the reliability of the proposed criteria for what was then known as "CSSD", Dimsdale reported that three groups had been studied for the field trials:

    488 healthy people;

    205 people with cancer and malignancy (some patients in this group were said to have severe coronary disease);

    94 people in a "functional somatic" group (said to include "irritable bowel" and "chronic widespread pain");

    Dr Dimsdale reported:

    that about 15% of the cancer and malignancy group met CSSD criteria if "one of the B type criteria" was required; if the threshold was increased to "two B type criteria" about 10% would meet the criteria for dual-diagnosis of cancer + "Somatic Symptom Disorder."

    For the 94 "functional somatic" study group, about 26% would be coded if one "B type" cognition was required; 13% were coded if two cognitions were required.

    About 7% of the "healthy" group were caught by the CSSD criteria.

    When the final draft for the DSM-5 was released, the proposed name for the new diagnosis had been changed from "CSSD" to "SDD".

    The number of "B type" criteria required to meet the diagnosis had also been changed - reduced from a requirement for two from the "B type" psychobehavioural responses to symptoms, to just one.

    For its third draft, rather than revise in favour of less inclusive criteria, Dimsdale's work group had lowered the threshold for a diagnosis of SSD, despite the considerable concerns expressed in stakeholders' submissions in the first and second review periods.

    I have still not been credited for the extracts from my text used by Coyne in his PLOS blog.
    Last edited: Dec 10, 2016
  15. Dx Revision Watch

    Dx Revision Watch Suzy Chapman Owner of Dx Revision Watch

    Extracts from:

    Submission from Suzy Chapman in the Third DSM-5 Comment and Review exercise (May 2 – June 15 2012)


    The SSD Work Group's framework "...will allow a diagnosis of somatic symptom disorder in
    addition to a general medical condition, whether the latter is a well-recognized organic
    disease or a functional somatic syndrome such as irritable bowel syndrome or chronic fatigue

    "...These disorders typically present first in non-psychiatric settings and somatic symptom
    disorders can accompany diverse general medical as well as psychiatric diagnoses. Having
    somatic symptoms of unclear etiology is not in itself sufficient to make this diagnosis. Some
    patients, for instance with irritable bowel syndrome or fibromyalgia would not necessarily
    qualify for a somatic symptom disorder diagnosis. Conversely, having somatic symptoms of an
    established disorder (e.g. diabetes) does not exclude these diagnoses if the criteria are
    otherwise met."

    [1] Justification of Criteria - Somatic Symptoms, May 4, 2011 for second DSM-5 stakeholder


    During the Q & A session at the end of Dr Dimsdale's APA Conference presentation, a
    questioner raised the issue that practitioners who are not clinicians or psychiatric
    professionals might have some difficulty interpreting the wording of the B type criteria to
    differentiate between negative and positive coping strategies.

    Dr Dimsdale was asked to expand on how the B type criteria would be operationalized and
    by what means patients with chronic medical conditions who devote time and energy to
    health care strategies to try to improve their symptoms and their level of functioning
    would be evaluated in the field by a very wide range of DSM users and differentiated from
    patients considered to be spending "excessive time and energy devoted to symptoms or
    health concerns"
    or perceived as having become "absorbed" by their illness and whose
    preoccupations were felt to be "disproportionate."

    By what means will the practitioner reliably assess an individual's response to illness
    within the social context of the patient's life and determine what should be coded as
    "excessive preoccupation" or indicate that this patient's life has become "subsumed" or
    "overwhelmed" by concerns about illness and "devotion" to symptoms?

    By what means would a practitioner determine how much of a patient's time spent
    "searching the internet looking for data" (to quote an example provided by Dr Dimsdale)
    might be considered a reasonable response to chronic health concerns within the context
    of this patient's experience?

    I am not reassured from Dr Dimsdale's responses that these B (1), (2) and (3) criteria can
    be safely applied outside the optimal conditions of field trials, in settings where
    practitioners may not necessarily have the time nor instruction for administration of
    diagnostic assessment tools, and where decisions to code or not to code may hang on
    arbitrary and subjective perceptions.


    In his journal article Medically Unexplained Symptoms: A Treacherous Foundation for
    Somatoform Disorders?
    [2] Dr Dimsdale discusses the unreliability of "medically
    unexplained" as a concept and acknowledges the perils of missed and misdiagnosis:

    "...On the face of it, MUS sounds affectively neutral but the term sidesteps the quality of the
    medical evaluation itself. A number of factors influence the accuracy of diagnoses. Most
    prominently, one must consider how thorough was the physician’s evaluation of the patient.
    How adequate was the physician’s knowledge base in synthesizing the information obtained
    from the history and physical examination? The time pressures in primary care make it
    difficult to comprehensively evaluate patients and thus contribute to delays and slips in
    diagnosis. Similarly, physicians can wear blinders or have tunnel vision in evaluating
    patients.1 Just because a patient has previously had MUS is no guarantee that the patient has
    yet another MUS. As a result of these factors, the reliability of the diagnosis of MUS is
    notoriously low..."

    For DSM-5 then, the Work Group proposes to deemphasize "medically unexplained" as the
    central defining feature of this disorder group and instead, shift the focus to the patient’s
    cognitions – "excessive thoughts, behaviors and feelings" about the seriousness of
    distressing and persistent somatic symptoms which may or may not accompany diagnosed
    general medical conditions – and the extent to which "illness preoccupation" is perceived to
    have come to dominate the patient’s life.

    Dr Dimsdale concludes:

    "Patients present with an admixture of symptoms, preconceptions, feelings, and illnesses. The
    task of psychiatric diagnosis is to attend to the patient’s thoughts, feelings, and behaviors
    that are determining his/her response to symptoms, be they explained or unexplained."

    In proposing to license the application of an additional mental health diagnosis for all
    illnesses if the clinician considers the patient also meets the criteria for a "bolt-on"
    diagnosis of SSD, Dr Dimsdale and colleagues appear hell bent on stumbling blindly from
    the "treacherous foundation" of the "somatoform disorders" into the quicksands of
    unvalidated constructs and highly subjective, difficult to measure criteria.


    Dr Dimsdale concedes his committee has struggled from the outset with these B type
    criteria but feels its proposals are "a step in the right direction."

    Patients deserve better than this; science demands rigor.

    In the absence of a substantial body of independent evidence for the SSD construct
    as a reliable, valid and safe alternative, I urge the Work Group not to proceed with its
    proposals for the reorganization of the "Somatoform Disorders" categories in favour
    of the status quo, or to dispense altogether with this section of DSM. There can be no
    justification for replacing one set of dysfunctional, unreliable and unsafe categories
    with another.

    [2] Dimsdale JE. Medically Unexplained Symptoms: A Treacherous Foundation for Somatoform Disorders? Psychiatr Clin N Am 34 (2011) 511–513 doi:10.1016/j.psc.2011.05.003
  16. Dx Revision Watch

    Dx Revision Watch Suzy Chapman Owner of Dx Revision Watch

    I'll stand corrected, but I can't recall Coyne expressing opinion on the DSM-5 proposals for SSD, either during the three review and comment periods, in 2010, 2011 and 2012, or since.

    Are his views on the final SSD characterization and criteria (for which a similar construct is proposed for ICD-11) posted anywhere? I'd be interested to know his position on SSD.
    Invisible Woman and Wildcat like this.
  17. Dx Revision Watch

    Dx Revision Watch Suzy Chapman Owner of Dx Revision Watch

    From Coyne's blog:

    Always the fault of those damn Brits, eh?

    Walitt, anyone?
  18. Wildcat


    @Dx Revision Watch wrote:
    'll stand corrected, but I can't recall Coyne expressing opinion on the DSM-5 proposals for SSD, either during the three review and comment periods, in 2010, 2011 and 2012, or since.'

    Coyne has definitely supported and vociferously promoted both Brian Walitt's and Edward Shorter's psychosomatic constructs of ME though. It looks like Coyne doesn't know if he's coming or going.

    Coyne still hasn't corrected the misattribution of quotes in his latest Blog either, despite having been informed that Allen Francis was not the author of the quotes which Coyne used (and has been informed that the author of the Quotes which Coyne used was in fact Suzy Chapman/Dx Revision Watch).

    That's shoddy.

    I wonder if Coyne has some particular reason to avoid correctly attributing the quotes to Suzy Chapman, because until he does he is currently adding insult to injury.
    Last edited: Dec 10, 2016
  19. Woolie

    Woolie Senior Member

    I just had a look, @A.B.

    The SF36 is a self-report questionnaire with eight different subscales e.g., mental health, physical functioning, vitality etc. You can add up all the subscales that relate to physical health (vitality, physical functioning, bodily pain, physical role functioning etc) and come up with what called a Physical Component Summary (PCS).

    These authors were going to use this PCS as their primary outcome measure, but changed their minds and went with another outcome measure: something they call an "aggregate measure", which includes just three physical subscales: physical functioning, bodily pain and vitality.

    They decided to use their own 3-subscale aggregate measure instead of the standard PCS (all physical subscale scores) for some weird reasons. They say:
    This makes no sense, as it applies only to large normative samples. It perfectly possible for physical and mental component summary measures to be negatively correlated in a small clinical sample.

    They also say:
    This is weird too, as the patients were a highly selected bunch, so you would expect certain scores to be clustered up one of the ends of the scale, not nicely evenly distributed like in a normative population.

    However, weirdly, its not clear to me that they did this switching to improve their results. Both alternative measures seemed to be equally good at yielding the results they wanted.
    Last edited: Dec 12, 2016
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  20. Dx Revision Watch

    Dx Revision Watch Suzy Chapman Owner of Dx Revision Watch


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