Naar aanleiding van een recent verschenen studie van Mira Meeus en collega's
heb ik een ingezonden brief gestuurd naar de redacteur van Clinical Rheumatology (zie onder).
Meeus, Nijs en anderen stellen op basis van subjectieve en objectieve criteria vast dat ME/CVS
gepaard gaat met grote beperkingen, cognitieve klachten en afgenomen spierkracht-/herstel.
Ook stellen zij artsen zich niet al te druk druk hoeven te maken over dat diagnosecriteria (1,
2 en 3).
Die "aanbeveling" doen zij o.m. op basis van het feit dat de symptomen en mate van invaliditeit
bij 10 CVS-patiënten die niet aan de Ramsay-criteria voldeden niet afweken niet noemenswaardig
afweken van die van de overige 38 CVS-patiënten die wel aan de Ramsay-criteria voldeden.
Het belangrijkste argument tegen de aanbeveling dat diagnosecriteria er nauwelijks toe doen
is het feit dat er geen vergelijking gemaakt is tussen "CVS"-patiënten mét post-exertional "malaise" (objectief vastgesteld) en "CVS"-patiënten zonder dit karakteristieke symptoom van ME.
Alhoewel de brief door de ene reviewer als ter zake doend en relevant werd beoordeeld,
was de andere reviewer van mening dat de "CVS"-criteria welllicht zelfs te strikt zijn en
dat het bewijs van de afwijkingen (in subgroepen) (referenties: zie onder) niet echt geleverd is.
Op grond van de beoordeling van die laatste reviewer werd de brief voor publicatie afgewezen.
En zo draaien we nog jaren en jaren in cirkeltjes rond...
What is in a name?
Post-exertional "malaise" the essence of ME (Myalgic Encephalomyelitis).
Twisk, FNM.
Abstract
The accuracy and relevance of the diagnostic criteria for
Myalgic Encephalomyelitis (ME) and/or chronic fatigue syndrome (CFS)
are subject of debate.
A recent study established severe impairment in CFS,
both objectively and subjectively.
Based upon their comparison of
the outcomes of subjective and objective measures of symptom burden
in those only meeting the CFS criteria and
those also fulfilling the original criteria for ME or the 2003 Canadian criteria,
the authors conclude that
the diagnostic criteria are of little relevance to clinicians.
Despite its great relevance,
this study fails to address a crucial issue:
a subdivision of patients with post-exertional "malaise":
a prolonged increase of “fatigue”, cognitive deficits, pain etc.
after minimal (physical or mental) exertion,
labelled ME patients,
and those without,
labelled CFS patients.
There is evidence that
ME and CFS patients
are distinct symptomatological and immunological patient subgroups.
This distinction and an accurate diagnosis,
based upon objective measures,
have important implications for
the effect of proposed effective therapies,
e.g. graded exercise therapy.
Keywords
Myalgic Encephalomyelitis, chronic fatigue syndrome,
assessment, post-exertional malaise, exercise
Letter
A recent study (1) provides a wealth of data on
the level of impairment in
Myalgic Encephalomyelitis (ME) / chronic fatigue syndrome (CFS),
both assessed subjectively as objectively.
Based upon the outcomes of subjective and objective measures
in those only meeting the CFS criteria and
those also fulfilling the criteria for ME,
as defined by Ramsay et al., or the 2003 Canadian criteria,
the authors conclude that
'[I]t seems that clinicians should not bother too much about the diagnostic criteria,
as long as either the 1994 CDC criteria [for CFS] or
the Canadian criteria [for ME/CFS] are used' (1).
While the study is indisputably of great relevance,
it fails to address a crucial issue (2):
the distinction between patients with post-exertional malaise,
a prolonged increase of “fatigue”, cognitive deficits, pain etc.
after minimal exertion, and
patients without this phenomenon (3).
As Meeus et al. (1) did with other symptoms,
e.g. cognitive deficits, muscle power and recovery,
the most crucial feature of ME (2), post-exertional malaise,
should be assessed objectively, e.g. by
a) by using repeated exercise tests (4,5);
b) comparing scores on (specific) cognitive tests before and after a single exercise test (6,7);
c) assessing cognitive test scores at various degrees of orthostasis (8,9); and
d) comparing the scores of two cognitive tests with 4-24h rest in-between.
Post-exertional "malaise", e.g. as indicated by
a decline in oxygen uptake at the anaerobic threshold and/or at peak exercise (5),
is present or not.
Subjective measures, e.g. visual analog scales scores (1),
are inadequate,
since healthy controls also report to experience post-exertional "malaise" (10).
Post-exertional "malaise" is reflected by distinctive immunological abnormalities (11).
A recent study established unique immunological abnormalities
in patients meeting the ICC criteria for ME (12),
in which post-exertional "malaise" is obligatory, and
patients only fulfilling the criteria for CFS, and
highly significant correlations
between the physical status and immune parameters in ICC patients (13).
Another study (14) observed neuroinflammation
in widespread brain areas in ME patients (12),
which was associated with the severity of neuropsychological symptoms.
Johnston et al. (15) found that
patients meeting the ICC criteria for ME
reported significantly lower scores for
physical functioning, physical role, bodily pain, and social functioning
than those that only meeting the CFS criteria.
Since there is debate about the name (1),
the diagnostic criteria, and the distinction between ME and CFS (2),
the lack of a comparison of
patients with post-exertional malaise (11), established objectively,
with patients without this anomaly is a missed opportunity.
Since
'the lack of power to compare
those fulfilling the [original] ME criteria and those who did not
prohibits drawing firm conclusions regarding these criteria' (1) and
the fact that there were
no comparisons made
between the clinical picture of
patients with and without post-exertional malaise and
other potentially essential criteria of ME (12),
the conclusion that
'clinicians should not bother too much about the diagnostic criteria' (1)
is very premature at the least.
As noted, post-exertional "malaise" is obligatory for the diagnosis ME
according to the recently published International Consensus Criteria for ME (12).
Whether these criteria are too restrictive
with regard to other essential symptoms (10)
remains to be elucidated.
In conclusion,
without investigating
the differences in the clinical picture of
(ME) patients with post-exertional "malaise", and
CFS patients without this symptom objectively and
with sufficient statistical power,
it is preliminary to conclude that
diagnostic criteria have little relevance.
It seems likely that
exercise therapies will intensify the symptoms
in patients with long-lasting post-exertional "malaise": ME patients.
Therefore an accurate diagnosis
using objective measures is crucial (2).
References
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What is in a name?
Comparing diagnostic criteria for chronic fatigue syndrome with or without fibromyalgia.
Clin Rheumatol.
doi: 10.1007/s10067-014-2793-x.
- Twisk FNM (2014)
The status of and future research into Myalgic Encephalomyelitis and chronic fatigue syndrome:
the need of accurate diagnosis, objective assessment, and
acknowledging biological and clinical subgroups.
Front Physiol 5:109.
doi: 10.3389/fphys.2014.00109.
- Twisk FNM, Arnoldus RJW (2013)
Comment and reply on:
ME is a distinct diagnostic entity, not part of a chronic fatigue spectrum.
Expert Opin Med Diagn 7:413-415.
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