Use of the Canadian criteria to diagnose CFS, British Medical Journal, 18 July 2011

July 20, 2011


From ‘Rapid Responses', British Medical Journal, 18 July 2011

Will adopting the Canadian criteria improve the diagnosis of chronic fatigue syndrome?

Esther M Crawley, Consultant Senior Lecturer Alastair Miller, Peter White
University of Bristol

Fiona Godlee suggests that adoption of the Canadian criteria to diagnose chronic fatigue syndrome (CFS) is a reasonable request (1). It may be reasonable, but is probably not practicable. These criteria require the assessment of some 65 discrete symptoms and 14 comorbid conditions, before even considering exclusionary conditions (2); a significant burden on both patients and doctors. More worrying is that “symptoms”, such as ataxia, “palpitations with cardiac arrhythmias”, and “loss of thermostatic stability” count towards the diagnosis, rather than suggesting alternative diagnoses.

All criteria used to diagnose CFS/ME require disabling fatigue lasting between 4 and 6 months; a varying number of symptoms and the exclusion of other illnesses that cause fatigue. There is no evidence that different diagnostic criteria diagnose a different condition (3). There has been a recent attempt to improve the “vaguely worded” Canadian criteria (4), incorporating elements of more orthodox research criteria (5). But these revised criteria still require assessment of too many symptoms of dubious validity. The one advantage of the Canadian criteria over alternative diagnostic criteria is that they require what many would regard as the characteristic feature of CFS, post-exertional malaise (6). This is something that may need incorporating in future definitions to help differentiate CFS from more general fatigue.

Esther Crawley, Consultant Senior Lecturer, University of Bristol, and Clinical lead, Bath specialist paediatric CFS/ME service, Royal National Hospital for Rheumatic Diseases, Upper Borough Walls, Bath BA1 1 RL

Alastair Miller, Consultant Physician, Tropical & Infectious Disease Department, Royal Liverpool University Hospital, Liverpool L7 8XP

Peter D White, Professor of Psychological Medicine, Wolfson Institute of Preventive Medicine, Barts and the London School of Medicine, Queen Mary University of London, EC1A 7BE.

References

1. Godlee F. Ending the stalemate over CFS/ME. BMJ 2011;342:d3956.

2. Carruthers BM, Jain AK, De Meirleir KL, et al. Myalgic Encephalomyelitis/Chronic Fatigue Syndrome: Clinical working case definition, diagnostic and treatment protocols. Journal CFS 2003;11:18- 154.

3. National Institute for Health and Clinical Excellence. Clinical guideline CG53. Chronic fatigue syndrome/myalgic encephalomyelitis (or encephalopathy): diagnosis and management. London, NICE, 2007. http://guidance.nice.org.uk/CG53.

4. Jason LA, Evans M, Porter N et al. The development of a revised Canadian myalgic encephalomyelitis chronic fatigue syndrome case definition. Am J Biochem Biotech 2010;6:120-135.

5. Reeves WC, Lloyd A, Vernon SD, et al. International Chronic Fatigue Syndrome Study Group. Identification of ambiguities in the 1994 chronic fatigue syndrome research case definition and recommendations for resolution. BMC Health Serv Res 2003;3(1):25.

6. Cornes O. Commentary: Living with CFS/ME. BMJ 2011;342:d3836.

Competing interests: PDW has done consultancy work for the Departments of Health and Work and Pensions and a re-insurance company.

Published 18 July 2011

6 thoughts on “Use of the Canadian criteria to diagnose CFS, British Medical Journal, 18 July 2011”

  1. Quote: ‘The one advantage of the Canadian criteria over alternative diagnostic criteria is that they require what many would regard as the characteristic feature of CFS, post-exertional malaise (6). This is something that may need incorporating in future definitions to help differentiate CFS from more general fatigue.’

    For me, this is the most important point here – as far as I’m concerned as a sufferer, post-exertional malaise is the worst problem – I could cope with the pain, the fatigue, the sleep problems etc., but I can’t find a way to get around the fact that if I do just a tiny bit more than usual, I suffer for days or weeks afterwards. I find it shocking that the so called ‘experts’ should be only saying that this central symptom ‘may’ need to be included in definitions. As far as I’m concerned it’s not ME without post-exertional malaise. I wonder what others here think.

    1. PEM is the key, but not the way some define it.

      Reeves has PEM defined as experiencing fatigue at a level of excercise which would not induce fatigue in a normal healthy person. That will include anyone ill and/or deconditioned.

      Do they have to redefine every term to make ME/CFS disappear.

      We need to ensure that the definition of PEM used is a physiologically abnormal response to exercise.

  2. Anne Robertson

    Three experts in the field of ME/CFS advising that “the assessment of some 65 discrete symptoms and 14 comorbid conditions, before even considering exclusionary conditions would place a significant burden on both patients and doctors” beggars belief. Ignoring the symptoms and co-morbid conditions places a far greater burden on the patient and suggests to me that they are (or choose to be) unfamiliar with all aspects of this condition. ME/CFS is a complex condition not simply a fatigue and a failure to acknowledge this and research accordingly is why there has been so little progress over the last thirty years. As for “More worrying is that “symptoms”, such as ataxia, “palpitations with cardiac arrhythmias”, and “loss of thermostatic stability” count towards the diagnosis, rather than suggesting alternative diagnoses”, simply confirms this.

  3. They are dragging their heels about using Canadian criteria because they know that if they do include PEM then less complex fatigue disorders – ie. the ones that respond to CBT and GET – will be clearly distinct from ME. These people do not want progress, they want to protect the status quo. As for putting ‘symptoms’ in inverted commas, this is ludicrous and only serves to illustrate how far these doctors are from understanding the reality of ME. Putting reality in inverted commas does not make it disappear.

  4. A concern I had about the original Canadian criteria is that they could have been used in an all-or-nthing way; however with the revised criteria, there are the gradations:
    ———
    “Meeting research versus clinical criteria: Table 1
    provides all the symptoms as specified in the Revised
    Canadian ME/CFS case definition. Some meet full
    criteria whereas others who are very symptomatic do
    not meet full criteria. We argue as we did with the
    Pediatric case definition (Jason et al., 2006) that those
    that meet full criteria are more homogenous and might
    be best used for research purposes and we now classify
    these individuals as meeting the ***Research ME/CFS
    criteria***. Still, others might have the illness but not meet
    one of the required criteria. We classified such
    individual as meeting ***Clinical ME/CFS criteria***. These
    individuals needed to have six or more months of
    fatigue and needed to report symptoms in five out of the
    six ME/CFS symptom categories (one of which has to
    be post exertional malaise, as it is critical to this case
    definition). In addition, for autonomic, neuroendocrine
    and immune manifestations, adults must have at least
    one symptom in any of these three categories, as
    opposed to one symptom from two of the three
    categories. We also have a category called ***Atypical
    ME/CFS***, which is defined as six or more months of
    fatigue, but having two to four ME/CFS symptoms.
    There is also a category called ***ME/CFS-Like***, which
    involves exhibiting all criteria categories but for a
    duration of fewer than 6 months. Further, a person
    could be classified as having ***ME/CFS in remission*** if
    the person had previously been diagnosed with CFS by
    a physician but was not currently meeting the Research
    ME/CFS Criteria, Clinical ME/CFS criteria, or Atypical
    ME/CFS criteria and must have 0 or 1 classic ME/CFS
    symptoms.”
    ——-

  5. “There is no evidence that different diagnostic criteria diagnose a different condition”.

    There’s also no evidence that the criteria Crawley and White would prefer to use diagnose people with the same condition either.

    Also the current misdiagnosis rate is so alarming that frankly, I find it hard to see how the CCC could do much worse.

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