I’ve written the following to answer questions about the different meanings of “ME/CFS”.
I have come to understand ME is a distinct disease that needs to be separated out from the broader patient groups labeled CFS, ME/CFS and post viral fatigue syndrome.
Terminology varies by country so please note my point of view is based on the U.S. usage of these terms.
I think of CFS or ME/CFS akin to the label of fruit and ME akin to the apple label.
The ME/CFS label has multiple meanings
ME/CFS (ME & CFS) - two separate conditions
ME/CFS as defined by the 2003 Canadian Consensus Criteria (precursor to the International Consensus Criteria (ICC))
ME/CFS as defined by the 2015 IOM/NAM report (now used by the U.S. CDC)
ME/CFS as per the 2021 NICE guidelines (UK)
ME/CFS Canadian Consensus Criteria (CCC)
The Canadian Consensus Criteria was written in 2003 by many of the same people who later went on to write the International Consensus Criteria (ICC). The CCC is a clinical criteria, but because it requires post-exertional malaise (PEM) it became preferred for research over the Fukuda-CFS criteria among ME researchers. CFS-Fukuda does NOT require PEM.
The IC Primer explains that the creation of the ICC was based on the CCC:
“The ICC advance the successful strategy of the Canadian Consensus Criteria (CCC) of grouping coordinated patterns of symptom clusters that identify areas of pathology. The criteria are designed for both clinical and research settings.”
ME/CFS - IOM/NAM Report
The introduction to the IOM/NAM report Beyond ME/CFS: redefining an illness report states that ME/CFS is an umbrella term referring to ME and CFS, as shown here:
“Despite having different definitions, ME and CFS often are used interchangeably to refer to an illness characterized by profound fatigue and autonomic and neurocognitive symptoms. Throughout this report, the umbrella term “ME/CFS” is used to refer to ME and CFS.”
See MEadvocacy’s comparison between the ICC and the IOM/NAM-ME/CFS criteria for specifics on how these criteria differ.
It looks to me like the ME/CFS-IOM report writers collected CFS and ME research. They then focused the new criteria on those things found in both ME and CFS conditions. Thus creating an ME/CFS criteria. This process left out many of the neurological, immunological and cardiac abnormalities seen only in ME.
ME/CFS - NICE Guidelines
The NICE guidelines for ME/CFS are similar to the IOM/NAM report’s criteria. But it is different enough to be listed separately.
ME-ICC is not the same as ME/CFS
The ME International Consensus Primer, written in 2012 by many experts in the biology of ME, discusses the importance of separating ME out of the broader category. Pg ii of the ME IC Primer states:
“Remove patients who satisfy the ICC from the broader category of CFS. The purpose of diagnosis is to provide clarity. The criterial symptoms, such as the distinctive abnormal responses to exertion can differentiate ME patients from those who are depressed or have other fatiguing conditions.
Not only is it common sense to extricate ME patients from the assortment of conditions assembled under the CFS umbrella, it is compliant with the WHO classification rule that a disease cannot be classified under more than one rubric.
The panel is not dismissing the broad components of fatiguing illnesses, but rather the ICC are a refinement of patient stratification. As other identifiable patient sets are identified and supported by research, they would then be removed from the broad CFS/CF category.”
Long COVID
I have seen articles equating Long COVID with ME/CFS. Long COVID is another umbrella diagnostic label. It includes patients who have various conditions caused by organ and vascular damage from COVID as well as patients with symptoms similar to ME/CFS as defined by the IOM/NAM report.
I personally don’t think ME suddenly stopped happening when COVID-19 arrived. We need thorough screening to find out how many people with ME are being lumped into the Long COVID diagnosis.
Patient Selection in Research
The importance of using strict criteria becomes clear when researchers choose subjects from the fruit category but state that the results apply to apples.
If a fruit researcher lives near strawberries, blackberries and blueberries while the apples require a long drive and a ladder, the researcher is very likely to study the combination of berries and not the apples.
They are all fruit so the researcher feels confident that results found in the berries can be applied to the apples.
We have seen for decades that results from people diagnosed with CFS often do not apply to people with ME. Benefits of exercise and CBT is a good example of results on people who could easily travel to clinical trials and take part in aggressive psychotherapy and exercise which brought positive results to this CFS patient group.
Researchers do the majority of their work in labs. People with ME are often too sick to leave home and participate. People who are less ill and who often fit into the broader post viral fatigue umbrella category (fruit) are able to go to the labs to be studied.
I think this situation has a lot to do with why there is an entrenched bias toward minimizing the reality of the severity of ME.
As more researchers took the time to drive to the orchard and use a ladder to reach the apples, a new picture emerged.
Research Shows Importance of Strict Patient Selection
How many apples are mixed in with the fruit?
Symptom-based clusters in people with ME/CFS: an illustration of clinical variety in a cross-sectional cohort (10 February 2023)states:
“Almost 90% of the participants fulfilled the Fukuda case definition, compared to 80%, 59% and 39% fulfilling the IOM, CCC and ME-ICC case definitions, respectively.”
The previous study indicates that the ME group (apples) may only be about 39%. We need more research to know if this is accurate. I think this may explain why some treatments that help those in the CFS group are often not helpful (or safe) for people like me.
The following study is just one of the studies showing significantly different findings in people with ME compared to those in the broader CFS category.
“Our study found left hippocampal subiculum, presubiculum, and fimbria volumes were significantly larger in ME/CFSICC patients compared with HC [healthy controls], but not for ME/CFSFukuda patients. Furthermore, this study demonstrated that multiple hippocampal subfield volumes are different in ME/CFSICC patients meeting the strict ICC case definition, and they exhibited strong associations with clinical measures.
Therefore, the strict case definitions are essential in investigation of the pathophysiology of ME/CFS. Subiculum and parasubiculum volumes were larger in ME/CFS in contrast to reductions seen in other neurological disorders.”
(ME/CFSICC refers to patients fitting the ICC.)
More evidence about the importance of stratification of patients for research can be seen in the stratification category in these ICC and CCC research lists. These lists are regularly updated.
The Future
For decades the view of ME has been based on the easy to reach fruit. ME patients who are hard to reach have been invisible. That needs to change.
Because I am confident I have ME as defined by the experts, I am looking to the researchers using the ICC to shed light on what is most likely to apply to my situation. I am grateful more researchers are indicating they see the importance of stratifying patients.
It is possible the researchers looking at the broader post viral fatigue group will find something important. I am hoping any promising findings seen in the broader patient group will be researched in the ME group. We desperately need to know which research findings apply to which group of patients.
Colleen
Information provided here or in comments is not to be considered medical advice
Sources
Committee on the Diagnostic Criteria for Myalgic Encephalomyelitis/Chronic Fatigue Syndrome; Board on the Health of Select Populations; Institute of Medicine. Beyond Myalgic Encephalomyelitis/Chronic Fatigue Syndrome: Redefining an Illness. Washington (DC): National Academies Press (US); 2015 Feb 10. 1, Introduction. Available from: https://www.ncbi.nlm.nih.gov/books/NBK284905/
Myalgic encephalomyelitis (or encephalopathy)/chronic fatigue syndrome: diagnosis and management; NICE guideline [NG206]Published: 29 October 2021
https://www.nice.org.uk/guidance/ng206
Myalgic Encephalomyelitis/Chronic Fatigue Syndrome: A Clinical Case Definition and Guidelines for Medical Practitioners An Overview of the Canadian Consensus Document Bruce M. Carruthers, M.D., C.M., FRCP(C) Marjorie I. van de Sande, B. Ed., Grad. Dip. Ed.
https://web.archive.org/web/20140212230705/http://www.cfids-cab.org/MESA/me_overview.pdf
The National Library of Canada Cataloguing-in-Publication Data: Myalgic Encephalomyelitis – Adult & Paediatric: International Consensus Primer for Medical Practitioners. ISBN 978-0-9739335-3-6
https://drive.google.com/file/d/1A0Bvtl4xRUkP3fEJSGMujdPaqQ1-QCIE/view
Vaes, A.W., Van Herck, M., Deng, Q. et al. Symptom-based clusters in people with ME/CFS: an illustration of clinical variety in a cross-sectional cohort. J Transl Med 21, 112 (2023). https://doi.org/10.1186/s12967-023-03946-6
Thapaliya, K., Staines, D., Marshall-Gradisnik, S., Su, J. & Barnden, L. (2022). Volumetric differences in hippocampal subfields and associations with clinical measures in myalgic encephalomyelitis/chronic fatigue syndrome. Journal of Neuroscience Research, 100, 1476–1486. https://doi.org/10.1002/jnr.25048
Ah, thank you for this detailed article. I saw your comment on a Facebook group I am in. I am also a Substacker. I subscribed to you. I actually believe that I have had CFS for 21 years since contracting Epstein-Barr virus when my kindergartener came home with mono.
But it’s just the last two years that I’ve had more of this nervous system dysregulation, sensory overstimulation, and PEM being triggered so consistently with physical, social, and/or cognitive effort. So I would say that I used to have only CFS and now I have ME/CFS the past two years (pneumonia was a trigger).
“Moderate” most days, which as you probably know very well means I have about 30-40% energy of a normal person.