PERMISSION TO REPOST
The authors' reply to the concerns about patients selection for research for this paper raises more problems in addition to those of the original paper. My comments here should be read in addition to other problems raised by authors on this forum.
Firstly, the authors express some resentment towards those legitimately have questioned this research cohort and the criteria over the years, which is rather surprising. Contrary to the insinuation by the authors, no person on the Plosone responses forum has insinuated that the research cohort they use are somehow 'less deserving' than say, the WPI cohort, purely that they are a different type of patient, using different criteria that select a different population, and that this may cause problems with the findings, and claims made based on those findings, with regard to the British 'CFS' population. This is a reasonable concern to express, and such a deduction can be made based on the evidence the authors provide themselves in their paper, citations, and their response. For example, their paper states:
"Patients in our CFS cohort had undergone medical screening to exclude detectable organic illness".
In the authors' response here, they also write:
"Thus patients in our service have also co operated in studies of PET and fMRI
neuroimaging, autonomic dysfunction, neurochemistry, respiratory function,
vitamin status, anti nuclear antibodies, immune function, neuroendocrine
function and genetics "
While patients being processed for a research cohort may well, indeed are likely, to have co-operated and had such tests done, this does not necessarily mean that patients with positive results are part of the research cohort. Indeed, positive results, which would indicate organic abnormality, would surely be likely to prevent a patient being selected for a cohort, by the very logic described in the author's paper here, by their own response (the additional tests are considered `not clinically necessary'?) and in at least one of their citations (Quarmby et al)? In the Quarmby et al paper, the cohort is described, in which the criteria used (in addition to 'Fukuda/CDC') is 'Oxford'. The Oxford criteria (Sharpe et al 1991) in particular actually do allow for patients who fulfil organic abnormality to be selected out of a research cohort. Indeed, Anthony David, referring to these, commented at the time:
"British Investigators have put forward an alternative, less strict, operational definition which is essentially chronic (6 months or more) severe disabling fatigue in the absence of neurological signs with myalgia, psychiatric symptoms and previous viral infections as common associated features."
Here special attention needs to be paid to the term `previous viral infections' and `absence of neurological signs', in order to contextualise the cohort selection process applied using the Oxford Criteria.
It is therefore quite reasonable to presume that patients in the cohort described in the Erlwein et al paper are less likely to be suffering from organic abnormalities associated with 'CFS' populations than in other research cohorts. It is also rational to be concerned that the cohort described here may not be representative of many people diagnosed with 'CFS' in Britain. NICE guidelines for example, acknowledge that very little research has been done on `severely affected' patients, who comprise, possibly at least 25% of the population of people given a `CFS' diagnosis (though so little research has been done on `severely affected` in Britain, the true number is not yet clear). While patients potentially destined for a research cohort which weeds out `detectable organic abnormality' may be subjected to a rigorous amount of investigations, those not undergoing this process do not undergo such testing, at least not in the NHS. Indeed, such investigations of clinical patients are severely proscribed in the majority of `guidelines': NICE, and the RCPCH guidelines as just two examples. Ironically, Fukuda guidelines also make the following comment:
"The use of tests to diagnose the chronic fatigue syndrome should be done only
in the setting of protocol-based research.
In clinical practice, no additional tests, including laboratory tests and
neuro-imaging studies, can be recommended. Examples of specific tests (which
should not be done) include serologic tests for enteroviruses; tests of
immunologic function, and imaging studies, including magnetic resonance imaging
scans and radionuclide scans (such as single photon emission computed tomography
(SPECT) and positron emission tomography (PET) of the head.
We consider a mental status examination to be the minimal acceptable level of
That clinical populations are not to be afforded the types of investigations given to research populations makes the whole idea of `medically unexplained' or `unexplained by disease', or 'functional' (as synonymous with 'non-organic' or not discernibly organic`) as common characterisations of CFS (including by at least one of the authors themselves in previous publications, for just one example, Page et al, 2003) highly problematic at best.
It is also significant that `CFS' is so often described as a `diagnosis of exclusion' (see, for example, the Centre for Disease Control CFS information website (Footnote: http://www.cdc.gov/cfs/cfsdiagnosis.htm) . Certain research case definitions comply with this assumption, such as the Oxford Criteria (Sharpe et al, 1991) and CDC Criteria (Fukuda et al, 1994) Here, `diagnosis of exclusion' also functions as a euphemism of `medically unexplained'. The key problem within this recurring theme in the literature, which most frequently remains un-addressed, is how a clinical patient's condition can all too easily become `medically unexplained' because of the practice of encouraging doctors to severely limit investigations in the first place: except, it would appear, ironically, in research populations in which `organic' illness is being weeded out to provide the type of cohort that might fulfil `not organically ill' definitions.
The issue of `disability' also needs to be clarified. The references cited in the Erlwein paper to support the statement that the patient cohort was of 'high levels of disability' refer only to 'disability' in psycho-social terms or feelings of `fatigue`, and not in terms of physical impairment, a key omission. Mundt et al's paper in particular focuses on specific mental health problems and the social exclusionary effects of living with these. While in no way invalidating or trivialising the disability caused by mental health problems, it must be pointed out that both Mundt et al and Chalder Scales nevertheless fail to elucidate a high level of physical or physiological (say, for example, neurological, mitochondrial and/or cardiovascular) impairment, key problems present in people given a clinical diagnosis of `CFS', usually related to specific organic abnormalities that can be found, if they are tested for in the first place.
With regard to the Canadian criteria (Carruthers et al), in fact they have undergone some `validation'. Jason et al found:
"…Canadian criteria selecting cases with less psychiatric co-morbidity, more physical functional impairment, and more fatigue/weakness, neuropsychiatric, and neurologic symptoms. The overall findings suggest that the Canadian clinical criteria appear to select a more symptomatic group of individuals than the CFS criteria, and these individuals do demonstrate less current and lifetime psychiatric impairment than those selected according to the CFS criteria. In contrast, the CFS group was not significantly different from the Chronic fatigue-psychiatric group in psychiatric impairment. Predictably, the Chronic fatigue-psychiatric group evidenced the highest frequency of current and lifetime psychiatric disorders… Overall, there were 17 significant symptom differences between the Canadian and Chronic fatigue-psychiatric group, but only 7 significant symptom differences between the CFS and Chronic fatigue-psychiatric group. Findings suggest that the Canadian criteria select a group of patients with more symptoms, and the Canadian criteria identify a group with higher levels of physical functional impairment and less psychiatric comorbidity. Findings from the present study indicate that the Canadian criteria does capture many of these cardiopulmonary and neurological abnormalities, which are not currently assessed by the current CFS case definition (Fukuda et al., 1994). However, it is worth noting that when the Fukuda et al. (1994) CFS case definition was conceived, the research had not yet been done investigating these abnormalities. In combination with symptom patterns, it is possible to conclude that the Canadian group does select individuals with greater impairment, particularly given the physical composite score, fatigue/weakness, neurologic and neuropsychiatric symptoms, as these symptoms can interfere with daily living and occupational performance. Results from this present investigation highlight the importance of contrasting different diagnostic criteria in order to gain a greater understanding of the syndrome now known as CFS. The findings do suggest that the Canadian criteria point to the potential utility in designating post-exertional malaise and fatigue, sleep dysfunction, pain, clinical neurocognitive, and clinical autonomic/ neuroimmunoendocrine symptoms as major criteria for future attempts to define this syndrome..." (http://www.mefmaction.net/Patients/Articles/Diagnosis/ComparingDefinitionsJL/tabid/223/Default.aspx )
In addition to using the Carruthers et al criteria (or `Canadian Criteria`), the WPI give this information about their patient cohort in their supporting online material:
"Their diagnosis of CFS is based upon prolonged disabling fatigue and the presence of cognitive deficits and reproducible immunological abnormalities. These included but were not limited to peturbations of the 2-5A synthetase/RNase L antiviral pathway, low natural killer cell cytotoxicity (as measured by standard diagnostic assyas) and elevated cytokines particularly interleukin-6 and interleukin-8. In addition to these immunological abnormalities, the patients characteristically demonstrated impaired exercise performance with extremely low VO2 max measured on stress testing..." (www.sciencemag.org/cgi/content/full/117905/DC1 )
It is therefore highly unlikely, as the authors indeed acknowledge in their reply here, that Erlwein et al were testing the same type of patient as those tested by the WPI, which inevitably makes the Erlwein et al findings- and perhaps some of the wilder claims that they have `cast serious doubt' on the WPI`s findings, unfortunately made in some of the lay media- not scientifically tenable. The failure of Erlwein et al to include such type of patient in their cohort, however. does not mean that such patients do not exist in Britain. Copious patient anecdotal experience, research reports, and charity surveys indicate that they do exist. Whether XMRV is present or not is another matter, but there are enough identifiable problems around patient selection alone with the Erlwein et al paper to indicate this is not a definitive disproving of the existence of the virus in Britain.
Ongoing neglect of the importance of establishing a possible `CFS' patient population in Britain, clinically and in research settings, using the Canadian Guidelines, is preventing the development of knowledge that might help extremely ill and disabled people here in Britain.
The problems I have briefly outlined here do not fully express the range and depths of problems with regard to: the identity of an accurate `CFS' population; the instabilities of `CFS' criteria per se; the faulty concepts of `medically unexplained' or `functional` and relation to `psychogenic` explanations for somatic illness; the vagaries of criteria that claim to facilitate a `diagnosis of exclusion'; and the psychogenic dismissal of serious organic dysfunction of patients given a 'CFS' diagnosis, problems that have happened for many years. These problems are relevant to the Erlwein et al paper. Furthermore, they are highly relevant to all research that claim a psychological and/or behavioural aetiology to the condition or conditions that get deemed as `CFS'.
Carruthers, B. et al (2003) "Myalgic Encephalomyelitis/Chronic Fatigue Syndrome: Clinical Working Case Definition, Diagnostic and Treatment Protocols" Journal of Chronic Fatigue Syndrome, Vol. 11(1), pp 7 - 115.
Chalder, T. Berelowitz, G. Pawlikowska, T. Watts, L. Wessely, S. Wright, D. Wallace, E. P. 'Development of a fatigue scale' Journal of Psychosomatic Research Vol 37: Issue 2: Feb 1993: 147-153.
David, A.S. `Postviral syndrome and psychiatry` British Medical Bulletin: 1991: 47: 4: 966-988
Fukuda K, Straus SE, Hickie I, Sharpe MC, Dobbins JG, Komaroff A. 'The chronic fatigue syndrome: a comprehensive approach to its definition and study' Ann Intern Med. 1994 Dec 15;121(12):953-9.
Jason LA, Torres-Harding SR, Jurgens A, Helgerson J. "Comparing the Fukuda et al. Criteria and the Canadian Case Definition for chronic Fatigue Syndrome". Journal of Chronic Fatigue Syndrome 12(1):37-52, 2004
Mundt, J.C. Marks, I.MShear, K. Griest, J.H. 'The work and social adjustment scale: a simple measurement of impairment in functioning' British Journal of Psychiatry (2002) 180: 461-443
Page, L.A. Wessely, S. 'Medically unexplained symptoms: exacerbating factors in the doctor–patient encounter' J R Soc Med 2003;96:223-227
Sharpe MC, Archard LC, Banatvala JE, Borysiewicz LK, Clare AW, David A, Edwards RH, Hawton KE, Lambert HP, Lane RJ, et al ' Chronic fatigue syndrome: guidelines for research' J R Soc Med. 1991 Feb;84(2):118-21.