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The acronym ME/CFS is commonly used as an umbrella term to cover the various case definitions employed to describe Myalgic Encephalomyelitis (ME) and/or Chronic Fatigue Syndrome (CFS) around the world. Case definitions vary widely, with some being so broad as to cover numerous unrelated illnesses.[1] Even among the narrower case definitions, it is unclear if (ME) is equivalent to (CFS), a specific form of it, or something entirely different. In ME/CFS research, the terms are often used synonymously, though there is no clear evidence to support either equating them or separating them.

In the UK and parts of Europe, the acronym is CFS/ME.


Myalgic encephalomyelitis[edit]

  • 1956, The name Myalgic Encephalomyelitis first appeared in medical literature.[2]

Chronic fatigue syndrome[edit]

ME & CFS used interchangeably[edit]

  • 1990's - 2000's, "The criteria focused on fatigue and not as much on the encephalitic (inflammation of the brain) features of the disorder." Doctors began using ME and CFS interchangeably due to the broad CFS definition.[6]

The ME name was not fully accepted by the medical and government health agencies while CFS was not found to be acceptable by patients and some health practitioners.

ME/CFS criteria developed[edit]

  • 2006, Rich Carson, founder of ProHealth, started a name change campaign.[8]

Why the acronym ME/CFS is used[edit]

ME/CFS is a hybrid term for a community and disease in transition. It combines the older and more broadly recognized “CFS” with the less stigmatized “ME,” which is becoming more commonly used. Many governments and health authorities have recently adopted the term “ME/CFS,” which has evolved to become the most accessible term to meet the needs of the broadest audience. The Solve ME/CFS Initiative adopted this name so that our organization would be accessible and understandable to medical, academic, patient, and government audiences alike.

Number afflicted and lost wages[edit]

ME/CFS afflicts up to 2.5 million Americans (and an estimated 17 million worldwide) and in the USA the total economic costs are $17-24 billion a year. The US numbers are from the Institute of Medicine report (IOM report) which used the Fukuda criteria (for defining CFS in research) and CCC (which defines either ME or CFS in research or in a clinical setting).[11][12]

Criteria comparison[edit]

From CFS vs SEID, Pg. 13[13]
Table 1
88% SEID - (Developed by the IOM report) PEM Required
92% Fukuda criteria - (CFS) (Used by committee that developed IOM report) PEM Optional
76% CCC - (ME/CFS) (Used by committee that developed the IOM report) PEM Optional
61% Four-symptom criteria - (ME/CFS) PEM Required
60% ICC - (ME) PEM Required

There are fewer ME-ICC patients and the numbers of afflicted and financial impact from the IOM report are not correctly attributed to ME or CFS but instead to ME/CFS as Fukuda criteria and CCC were used by the authors of the IOM report.[14]

Results: At 6 months of illness, SEID criteria identified 72% of all subjects, similar to when Fukuda criteria (79%) or the CCC (71%) were used, whereas the ME-ICC selected for a significantly lower percentage (61%, p < .001). When severity/frequency thresholds were added to the Fukuda criteria, CCC and ME-ICC, the percentage of these subjects also fitting SEID criteria increased to 93%, 97%, and 95%. Eighty-seven percent of SEID subjects endorsed cognitive impairment and 92%, OI; 79% experienced both symptoms.
Conclusions: SEID criteria categorize a similar percentage of subjects as Fukuda criteria early in the course of ME/CFS and contain the majority of subjects identified using other criteria while requiring fewer symptoms. The advantage of SEID may be in its ease of use.

When Fukuda criteria, CCC and ME-ICC have severity/frequency thresholds added patients will meet SEID criteria. This is advantageous in a clinical setting as patients can be diagnosed by a Primary/GP/Family Doctor using SEID and then the patient can go through the process of receiving a CFS, ME/CFS or ME diagnosis from a doctor/researcher using Fukuda, CCC or ME-ICC until a Biomarker is found.


  • It is believed by some in the ME, CFS and ME/CFS community that the name Chronic Fatigue Syndrome and then the Myalgic Encephalomyelitis/Chronic Fatigue Syndrome name are a product of medical insurance companies, possibly in an effort to define the disorder as a behavioral illness similar to hypochondria or malingering. Insurance companies could benefit from this viewpoint, since behavioral illnesses are much less expensive to treat than physical illnesses, and in many cases, are not covered by insurance at all.[15]

Learn more[edit]

See also[edit]


  1. What is Myalgic Encephalomyelitis & Chronic Fatigue Syndrome? - ProHealth
  2. Synonyms of Myalgic Encephalomyelitis - NORD - By: Lenny Jason
  3. Synonyms of Myalgic Encephalomyelitis - NORD - By: Lenny Jason
  4. Synonyms of Myalgic Encephalomyelitis - NORD - By: Lenny Jason
  5. How disease names can stigmatize OUP Blog - By: Leonard Jason
  6. Synonyms of Myalgic Encephalomyelitis - NORD - By: Lenny Jason
  7. Myalgic Encephalomyelitis/Chronic Fatigue Syndrome - A Clinical Case Definition and Guidelines for Medical Practitioners - An Overview of the Canadian Consensus Document
  8. ProHealth - About Us
  9. IACFS/ME - 2007 Oslo, Norway
  10. Name Change Efforts Over Time - Phoenix Rising
  11. BEYOND Myalgic Encephalomyelitis/Chronic Fatigue Syndrome Redefining an Illness - National Academies of Medicine of Sciences Engineering Medicine
  12. ME Prevalence by State and Congr District
  13. Chronic Fatigue Syndrome versus Systemic Exertion Intolerance Disease, HHS Public Access
  14. Institute of Medicine (USA); Committee on the Diagnostic Criteria for Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (10 February 2015), Beyond Myalgic Encephalomyelitis/Chronic Fatigue Syndrome: Redefining an Illness 
  15. Who benefits from 'CFS' and 'ME/CFS'? - By: The Hummingbirds' Foundation for M.E. By: Jodi Bassett

The information provided at this site is not intended to diagnose or treat any illness.

From MEpedia, a crowd-sourced encyclopedia of ME and CFS science and history