Definitions of myalgic encephalomyelitis and chronic fatigue syndrome

Over the course of three decades, many definitions or case criteria have been developed to diagnose either myalgic encephalomyelitis (ME), chronic fatigue syndrome (CFS), or Systemic Exertion Intolerance Disease (SEID) which is an ME/CFS criteria. Some of these definitions or criteria are meant only to be diagnostic, i.e., used in a clinical setting to aid in diagnosis and some are meant to be used both in a clinical and research setting.

Each of these criteria and case definitions have been considered lacking in complete reliability and accuracy. Another change in the definition is assumed when medical research uncovers more of the pathophysiology of this illness.

ME

• 1986 Ramsay definition
• 2007 Nightingale definition
• 2011 International Consensus Criteria (ICC)
• 2014 London criteria

The International Consensus Criteria is currently used in some research and by few clinicians in some countries. Ramsay definition, Nightingale definition and London criteria are currently not in use.

CFS

• 1988 CDC case definition ("Holmes criteria")
• 1991 Oxford criteria*
• 1994 CDC case definition ("Fukuda criteria")* (CDC-1994)
• 2005 CDC case definition ("Reeves criteria")*

The Holmes criteria is currently not in use. The Oxford criteria is used in the UK by clinicians and researchers. Fukuda criteria is used in research by several countries including the US and sometimes in the UK. Reeves criteria is currently being used in the NIH Post-Infectious ME/CFS Study but overall it is not in use.

Combined (ME/CFS)

• 2003 Canadian Consensus Criteria (CCC)
• 2007 NICE guidelines*

The Canadian Consensus Criteria is sometimes used by clinicians and for research in many countries but has not been officially adopted by most countries including the US. NICE guidelines are used by clinicians in the UK.

Note: ME/CFS (or CFS/ME in the UK and parts of Europe) is the acronym now used in the US and some other countries.

'SEID'

• 2015 Institute of Medicine (IOM) diagnostic criteria
• The name "Systemic Exertion Intolerance Disease" (SEID) was proposed in conjunction with this criteria, but was not adopted.

The IOM criteria is an ME/CFS criteria proposed for use in the US in clinical settings. The NIH Post-Infectious ME/CFS Study is using this criteria along with three other criteria.

The Centers for Disease Control and Prevention (CDC) outlines the IOM diagnostic criteria on their ME/CFS page IOM 2015 Diagnostic Criteria.

Note on Definition flaws

Definitions with a asterisk (*) are considered to be by most ME/CFS patients, many ME/CFS patients groups, and several ME/CFS researchers as being seriously flawed in that these criteria capture individuals suffering from chronic fatigue and not chronic fatigue syndrome, myalgic encephalomyelitis or Systemic Exertion Intolerance Disease.

Comparison

• 2003, Jason, Leonard A.; Helgerson, Jena; Torres-Harding, Susan R.; Carrico, Adam W.; Taylor, Renee R. (March 2003), "Variability in diagnostic criteria for chronic fatigue syndrome may result in substantial differences in patterns of symptoms and disability", Evaluation & the Health Professions, 26 (1): 3–22, ISSN 0163-2787, PMID 12629919

• 2012, Jason, Leonard A.; Brown, Abigail; Clyne, Erin; Bartgis, Lindsey; Evans, Meredyth; Brown, Molly (September 2012), "Contrasting case definitions for chronic fatigue syndrome, Myalgic Encephalomyelitis/chronic fatigue syndrome and myalgic encephalomyelitis", Evaluation & the Health Professions, 35 (3): 280–304, doi:10.1177/0163278711424281, ISSN 1552-3918, PMID 22158691

• 2015, Accurate diagnosis of myalgic encephalomyelitis and chronic fatigue syndrome based upon objective test methods for characteristic symptoms (Frank Twisk)
• 2015, Case Definition Comparison - Graph 1
• 2016, Chronic Fatigue Syndrome versus Systemic Exertion Intolerance Disease (Leonard Jason)
• 2017, Patients diagnosed with Myalgic encephalomyelitis/chronic fatigue syndrome also fit systemic exertion intolerance disease criteria (Lily Chu), (Jane Norris), (Ian Valencia) & (Jose Montoya)

Learn more

• CFS vs SEID - Tandfonline The Four-symptom criteria is noted.
• CFS and ME: Toward An Empirical Case Definition - NCBI - NLM - NIH.gov See: Graph - 1
• Excluding Factors: Jason Critiques the IOM Definition for ME/CFS - Health Rising - Cort Johnson The Four-symptom criteria is noted.

See also

• Primer for the public (Disease names and acronyms around the world section)
• Case Definition Comparison - Graph 1
• DePaul Symptom Questionnaire
• Four-symptom criteria

systemic exertion intolerance disease (SEID) - A term for ME/CFS that aims to avoid the stigma associated with the term "chronic fatigue syndrome", while emphasizing the defining characteristic of post-exertional malaise (PEM). SEID was defined as part of the diagnostic criteria put together by the Institute of Medicine (IOM) report of 10 February 2015.

accuracy The "closeness of an observation to the true clinical state". With respect to diagnostic tests, "accuracy" means how specific and sensitive the test is.

International Consensus Criteria (ICC) - A set of diagnostic criteria, based on the Canadian Consensus Criteria, that argued for the abandonment of the term "chronic fatigue syndrome" and encouraged the sole use of the term "myalgic encephalomyelitis".

Centers for Disease Control and Prevention (CDC) - The Centers for Disease Control and Prevention is a U.S. government agency dedicated to epidemiology and public health. It operates under the auspices of the Department of Health and Human Services.

Canadian Consensus Criteria (CCC) - A set of diagnostic criteria used to diagnose ME/CFS, developed by a group of practicing ME/CFS clinicians in 2003. The CCC is often considered to be the most complex criteria, but possibly the most accurate, with the lowest number of patients meeting the criteria. Led to the development of the International Consensus Criteria (ICC) in 2011.

National Academy of Medicine (NAM) - An American non-profit, non-governmental organization which provides expert advice to governmental agencies on issues relating to biomedical science, medicine and health. Formerly known as the Institute of Medicine (IOM).

systemic exertion intolerance disease (SEID) - A term for ME/CFS that aims to avoid the stigma associated with the term "chronic fatigue syndrome", while emphasizing the defining characteristic of post-exertional malaise (PEM). SEID was defined as part of the diagnostic criteria put together by the Institute of Medicine (IOM) report of 10 February 2015.

myalgic encephalomyelitis (M.E.) - A disease often marked by neurological symptoms, but fatigue is sometimes a symptom as well. Some diagnostic criteria distinguish it from chronic fatigue syndrome, while other diagnostic criteria consider it to be a synonym for chronic fatigue syndrome. A defining characteristic of ME is post-exertional malaise (PEM), or post-exertional neuroimmune exhaustion (PENE), which is a notable exacerbation of symptoms brought on by small exertions. PEM can last for days or weeks. Symptoms can include cognitive impairments, muscle pain (myalgia), trouble remaining upright (orthostatic intolerance), sleep abnormalities, and gastro-intestinal impairments, among others. An estimated 25% of those suffering from ME are housebound or bedbound. The World Health Organization (WHO) classifies ME as a neurological disease.