JUMP | 1969 WHO Classification | 1986 Ramsay Definition | CDC 1988 Definition (Holmes) | Oxford 1991 Definition | CDC 1994 Definition (Fukuda) | 1994 London Definition | 2003 Canadian Consensus Criteria (CCC) | CDC 2005 Empiric Definition | 2010 Revised Canadian Consensus Definition (CCC) | 2011 International Consensus Criteria (ICC) | NIH/IOM 2015 Definition (SEID)
Since the first documented outbreak of a chronic fatigue-like illness over 200 years ago1, there has there been little evidence of progress in the treatment, diagnosis and social acknowledgement of a disease which affects as many as 2.5 million in the US alone2.
Much of the debate about the illness, commonly referred to as CFS, ME or conflated to ME/CFS, is still mired in uncertainties about the nature of symptoms, causes and biological processes, and the presumed effectiveness and safety of so called biopsychosocial interventions such as cognitive behavioral therapy (CBT) and graded exercise therapy (GET).
Over the years, although a number of formal definitions of the illness, called criteria, have guided clinical diagnosis and treatment of ME and CFS, determined government policy on research funding, even influenced public perceptions about its nature and severity, consensus between researchers, governments and even patients on which criteria is best suited is far from settled.
The criteria for the illness actually define two distinct, partially overlapping, entities: Myalgic Encephalomyelitis (ME) and Chronic Fatigue Syndrome (CFS).
Fundamental to the historical narrative of the illness, says Frank Twisk, is the reality that although ME and CFS are considered to be the same, the criteria define two distinct, partially overlapping, clinical entities3.
In the video below, Leonard Jason presents his extensive research into the merits and weaknessses of ME/CFS definitions at the 2014 NIH P2P Workshop.
Fundamental differences between ME and CFS
Twisk goes on to define ME and CFS separately:
Myalgic Encephalomyelitis (ME) is a neurological disease4,5 that has been described in the medical literature since 1934 under various names6, including epidemic neuromyasthenia and atypical poliomyelitis, often relating to outbreaks7,8,9.
Characteristic symptoms of ME, classified as a disease of the nervous system by the WHO since 196910, are muscle weakness, neurological dysfunction, especially of cognitive, autonomic and neurosensory functions; variable involvement of the cardiac and other systems; a prolonged relapsing course; but above all general or local muscular fatigue after minimal exertion with prolonged recovery times (post-exertional malaise)2.
According to commonly used criteria for CFS2 chronic fatigue must be accompanied by at least four out of eight symptoms, e.g., tender lymph nodes and muscle and joint pain.
However, five of the eight minor symptoms, i.e., headaches, lymph node pain, sore throat, joint pain, and muscle pain, do not differentiate people with melancholic depression group from healthy controls15.
Myalgic Encephalomyelitis (ME) is a neurological disease defined by the WHO, while the diagnosis Chronic Fatigue Syndrome (CFS) is primarily based upon a vague notion of chronic fatigue.
Why it matters
If the illness can be differentiated by symptom severity and functional impairment, in a sense so can the different criteria. For example, the Canadian Consensus Criteria (CCC) identifies a subset of ME/CFS patients with more functional impairments and physical, mental, and cognitive problems than the Fukuda Definition ((Jason LA, Brown A, Clyne E, Bartgis L, Evans M, Brown M. Contrasting Case Definitions for Chronic Fatigue Syndrome, Myalgic Encephalomyelitis/Chronic Fatigue Syndrome and Myalgic Encephalomyelitis. Evaluation & the health professions. 2012;35(3):280-304. doi:10.1177/0163278711424281. [Full Text])).
1969 WHO Classification
1986 Ramsay Definition
CDC 1988 Definition (Holmes)
Oxford 1991 Definition
CDC 1994 Definition (Fukuda)
1994 London Definition
Canadian Consensus Criteria (CCC) – 2003
2005 Empiric Definition
2010 Revised Canadian Consensus Criteria (RCCC)
NIH/IOM 2015 Definition (SEID)
2011 International Consensus Criteria (ICC-ME)
In the video below, Prof Leonard Jason explains why good definitional criteria are important for ME/CFS, and exposes the weakness of those definitions in use up to 2010.
Benign Myalgic Encephalomyelitis was classified in 196910 as a neurological disease by the World Health Organisation in its International Classification of Disease (currently listed under Other disorders of brain:Postviral fatigue syndrome:WHO ICD 10 G93.3).
Following the Royal Free Hospital outbreak in the UK, Wallis (1955) and Acheson (1959) made the earliest attempts to formally describe the disease, their descriptions focusing on the hallmark muscular and neurological symptoms, including ease of fatigability and potentially relapsing and remitting course. Acheson coined the term ‘Myalgic Encephalomyelitis’ (1956) reflecting the muscular, brain and CNS involvement thought characteristic of the disease.
Then in 1986 Ramsay published a definition21 of this disease using the term myalgic encephalomyelitis and the term benign was dropped due to the seriousness of the disability created by the illness22.
Ramsay’s criteria differentiated the disease into two main groups: symptoms at onset and symptoms in chronic state. He further differentiated the chronic state into three main groups: muscle phenomena, circulatory impairment, and cerebral dysfunction. Interestingly, fatigue was not a cardinal feature of Ramsay’s chronic state ME.
1990 Revised Ramsay Definition. In 1990, Ramsay collaborated with Dr Elizabeth Dowsett, to publish revisions to his definition, which emphasized an initial viral trigger, and also introduced the concept of prolonged recovery time23.
Note, Ramsay’s Definition did not use validated criteria published in a peer review journal.
For details of the criteria of 1986 and 1990 Ramsay Definitions, toggle the panels below.
The first US chronic fatigue syndrome definition, the CDC 1988 Definition, perhaps better known as the Holmes Definition, introduced the term chronic fatigue syndrome in an attempt to better describe the symptom complex previously known as chronic Epstein-Barr virus syndrome.24
Guided by the US Centers for Disease Control and Prevention (CDC), the Holmes working group documented concern regarding the invalidity of Epstein-Barr virus serologic tests and the lack of a causal relationship between Epstein-Barr virus infection and some patients who had been diagnosed with the chronic Epstein-Barr virus syndrome.
The 1988 definition was proposed for research purposes, as a basis for future epidemiologic and clinical studies, with the understanding that it did not necessarily define a single disease but a syndrome – a complex of potentially related symptoms that may have several causes.
According to this case definition, individuals needed to report 6 or more months of persistent or relapsing, debilitating fatigue that does not resolve with bedrest.
Also, participants were required to report at least 8 of 11 minor symptoms (fever or chills, sore throat, lymph node pain, muscle weakness, muscle pain, postexertional malaise, headaches of a new or different type, migratory arthralgia, neuropsychiatric complaints, sleep disturbance, and a sudden onset of symptoms).
Participants were also required to report at least a 50% impairment of daily functioning, as compared to premorbid levels.
The new definition shifted the focus of the disease away from Ramsay’s earlier work and in so doing omitted or under-emphasized many of its cardinal symptoms instead giving undue prominence to chronic fatigue.
Another major concern was that the requirement of eight or more minor symptoms could inadvertently select for individuals with psychiatric problems25.
For details of the CDC 1988 Definition (Holmes) criteria, toggle the panel below.
In 1991, a small group of British psychosocial psychiatrists (Sharpe et al)26 created guidelines to facilitate their research into fatiguing conditions.
The guidelines became known as the Oxford 1991 Definition and included CFS of unknown etiology and a subtype of CFS called post-infectious fatigue syndrome (PIFS), which “either follows an infection or is associated with a current infection.”
However, in reality, this definition shifted the focus of the illness away from the biological entity described in Ramsay’s Definition (1986) and the London Definition (1994) towards a biopsychosocial model.
The presence of mental fatigue is required to fulfill the criteria and symptoms are accepted that may suggest a psychiatric disorder27.
Shortly after publication of the Oxford criteria Anthony David wrote: “British investigators have put forward an alternative, less strict, operational definition which is essentially chronic fatigue in the absence of neurological signs (but) with psychiatric symptoms as common associated features”31.
Less specific criteria, based on the presence or absence of fatigue as the only mandatory symptom, increased the likelihood of patients with primary psychiatric disorders being included in trial cohorts labeled with CFS32,33,34.
For details of the Oxford 1991 Definition criteria, toggle the panel below.
The CDC 1994 Definition for CFS (1994), also known as the Fukuda Definition, was a US Centers for Disease Control and Prevention (CDC) initiative, primarily developed for research studies of CFS in adults. It is currently favored for use research and clinical diagnosis.
The Fukuda Definition requires a person to experience 6 or more months of chronic fatigue of a new or definite onset, that is not substantially alleviated by rest, not the result of ongoing exertion, and results in substantial reductions in occupational, social, and personal activities.
Because the Fukuda criteria only require four symptoms out of a possible eight, critical CFS symptoms such as postexertional malaise, and memory and concentration problems are not required of all patients.
The Fukuda definition is regarded as less specific than the Holmes criteria which selected a group of patients with higher symptomatology and functional impairment35.
Furthermore, these differences do not appear to be influenced by psychiatric variables, as they occurred in the absence of differences in rates of psychiatric comorbidity between the two groups35.
Another criticism is that Fukuda lacks clinical application, that it is characterized by vaguely worded criteria that are lacking operational definitions and guidelines to assist health care professionals in their interpretation and application of the diagnostic tool36.
Several investigations have contrasted the Holmes and Fukuda Definitions. In a study of 2,376 primary care patients, 1.2% of the sample were diagnosed with CFS by using the 1988 case definition (Holmes), compared to 2.6% using the 1994 case definition (Fukuda)37.
Another study of 71 primary care patients with CFS found that participants meeting only the 1994 definition experienced a greater duration of illness than those meeting the 1988 definition38. In contrast, those in the 1988 group reported greater frequency of sore throats, joint pain, tender lymph nodes, headaches, and fever. Finally, the 1988 group was more likely to report a sudden illness onset and a greater reduction in premorbid activity levels than the 1994 group.
For a full list of the CDC 1994 Definition (Fukuda) criteria, toggle the panel below.
The 1994 London Definition, based on Dr Melvin Ramsay’s clinical description of ME, was developed on behalf of M.E. Action, now Action for M.E. (AfME), for research purposes. Although these criteria were an improvement over the Oxford criteria, their legitimacy has been compromised – they have never been published or submitted for peer review, nor have they been consistently defined or validated.
The London Definition places an emphasis on exercise-induced muscle fatigue plus delayed recovery of muscle power after exertion ends, evidence of central nervous involvement and impaired circulation (also known as the diagnostic triad).
Two versions of the London Definition appeared around 1993/94. Version 1 was devised for AFME. A truncated and inaccurate revision39, Version 2, published in the 1994 National Task Force Report40 did not include the exclusion diagnoses and the physical examination findings.
Another subverted form of the London Definition, based on version 1, was used as secondary criteria in the PACE trial, after the application of the fatigue-based Oxford to exclude those with neurological symptoms, contrary to the original purpose of the original version41.
So it should be noted that the only documented application of the London Definition, in the PACE trial, was to filter out serious illness and focus more on fatigue (as a psychological component).
For a full list of each of the London Definition criteria, toggle the panels below.
The Canadian Consensus Criteria (CCC)42 were written in 2003 by ME/CFS professionals for use in clinical practice.
The CCC diverged from Fukuda by de-emphasizing fatigue as the sole major (compulsory) criteria, and elevating the importance of other cardinal symptoms, including post-exertional malaise, pain, sleep disturbances, and cognitive dysfunction.
Jason et al. found that CCC captured many of the cardiopulmonary and neurological abnormalities which were not currently assessed by the Fukuda criteria15.
Furthermore, Jason also found that CCC also selected cases with “less psychiatric co-morbidity, more physical functional impairment, and more fatigue/weakness, neuropsychiatric, and neurological symptoms” and individuals selected by these criteria were significantly different from psychiatric controls with CFS.
2010 Revised Canadian Consensus Definition (CCC). In 2010 the Revised Canadian Consensus Definition43 specified explicit rules for determining whether critical symptoms meet ME/CFS criteria and a questionnaire was developed to assess core symptoms.
It was intended that these developments would lead to increased reliability of the Canadian case definition as well as more frequent use of these criteria by investigators.
For a full list of the 2003 Canadian Consensus Criteria for ME/CFS, toggle the panel below.
The CDC set out to address criticisms that Fukuda lacked standardized reproducible criteria with the publication of the CDC 2005 Empiric Definition44, also known as the Reeves Definition.
The Reeves Definition assesses disability using the Medical Outcomes Survey Short-Form-36 (Ware, Snow, & Kosinski, 2000), assesses symptoms using the Symptom Inventory (Wagner et al., 2005), and assesses fatigue using the Multidimensional Fatigue Inventory (Smets, Garssen, Bonke, & DeHaes, 1995).
An evaluation of the Reeves Definition compared 27 patients with a prior diagnosis of CFS with 37 patients diagnosed with a Major Depressive Disorder. The researchers reported that 38 percent of those with a diagnosis of a Major Depressive Disorder were misclassified as having CFS using the new CDC definition45.
Leonard Jason criticized the diagnostic utility of the definition because it lacked sensitivity and specificity46.
The purpose of rigour had not been achieved, and the Reeves Definition was never broadly implemented.
For a full list of the Empiric Definition, toggle the panel below.
Consistent with the neurological classification of ME in the World Health Organization’s International Classification of Diseases (ICD G93.3), the International Consensus Criteria (ICC-ME) were developed in 2011 by an International Consensus Panel consisting of clinicians, researchers, teaching faculty and an independent patient advocate.
The ICC-ME defines myalgic encephalomyelitis (ME) as an acquired neurological disease with complex global dysfunctions. Pathological dysregulation of the nervous, immune and endocrine systems, with impaired cellular energy metabolism and ion transport are prominent features.
The ICC-ME arose out of the Canadian Consensus Criteria (CCC), with some significant changes:
- The 6-month waiting period before diagnosis is no longer required.
- Less focus on fatigue.
- Redefined ‘post exertional malaise’ and introduced the terminology ‘postexertional neuroimmune exhaustion’ (pene).
For a full list of the ICC-ME criteria, toggle the panel below.
The recently proposed NIH/IOM 2015 Definition2 (SEID) diagnostic criteria developed by the US Institute of Medicine (IOM) at the request of the Department of Health and Human Services (HHS) redefines CFS for clinical application.
The IOM recommended that the name of the disease be changed from ME/CFS to Systemic Exertion Intolerance Disease (SEID).
Also on Shoutout About ME:
The IOM concluded that the term myalgic encephalomyelitis was inappropriate because there was a lack of evidence for encephalomyelitis (brain inflammation) in ME/CFS patients, and myalgia (muscle pain) was not a core symptom of the disease (this point is heavily disputed by researchers and patient groups).
SEID was not intended to replace usage of ME.
According to the IOM, “This name captures a central characteristic of the disease: the fact that exertion of any sort—physical, cognitive, or emotional—can adversely affect patients in many organ systems and in many aspects of their lives. The committee believes systemic exertion intolerance disease appropriately captures the complexity and severity of the illness.”
The new criteria were not evaluated with data sets of patients and controls49. Findings suggest that the new criteria select more patients who have less impairment and fewer symptoms than several other criteria49.
SEID may also categorize many individuals with major depressive disorder, as well as other medical illnesses50.
As a result of omitting these exclusions, SEID increased the prevalence rate for the illness of 0.42 percent as defined by Fukuda, by 2.8 times50.
For a full list of the NIH/IOM 2015 Definition (SEID) criteria for ME/CFS, toggle the panel below.
- Lorusso L, Mikhaylova SV, Capelli E, Ferrari D, Ngonga GK, Ricevuti G (February 2009). Immunological aspects of chronic fatigue syndrome. Autoimmun Rev 8 (4): 287–91. doi:10.1016/j.autrev.2008.08.003. PMID 18801465. [Abstract] ↩
- 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. [Abstract], [Full Report] ↩ ↩ ↩ ↩
- Twisk, FN. Accurate diagnosis of myalgic encephalomyelitis and chronic fatigue syndrome based upon objective test methods for characteristic symptoms. World J Methodol. 2015 June 26; 5(2): 68-87. [Full Text] ↩
- Dowsett EG, Ramsay AM, McCartney RA, Bell EJ. Myalgic encephalomyelitis – a persistent enteroviral infection?. Postgrad Med J. 1990;66:526-530. [PubMed], [Full Text] ↩
- Parish JG. Early outbreaks of ‘epidemic neuromyasthenia’. Postgrad Med J. 1978;54:711-717. [PubMed], [Full Text] ↩
- Acheson ED. The clinical syndrome variously called benign myalgic encephalomyelitis, Iceland disease and epidemic neuromyasthenia. Am J Med. 1959;26:569-595. ↩
- Gilliam AG. Epidemiological study on an epidemic, diagnosed as poliomyelitis, occurring among the personnel of Los Angeles County General Hospital during the summer of 1934. Washington, DC: United States Treasury Department Public Health Service Public Health Bulletin; 1938.pp.1-90. ↩
- Crowley N, Nelson M, Stovin S. Epidemiological aspects of an outbreak of encephalomyelitis at the Royal Free Hospital, London, in the summer of 1955. J Hyg (Lond). 1957;55:102-122. [PubMed] ↩
- Strickland PS, Levine PH, Peterson DL, O’Brien K, Fears T. Neuromyasthenia and chronic fatigue syndrome (CFS) in Northern Nevada/California: a ten-year follow-up of an outbreak. J Chronic Fatigue Syndr. 2001;9:3-14. [DOI] ↩
- International Classification of Diseases, Eighth Revision (ICD-8): I (Code 323): 158. Geneva: Switzerland; 1967. ↩ ↩
- Holmes GP, Kaplan JE, Gantz NM, Komaroff AL, Schonberger LB, Straus SE, Jones JF, Dubois RE, Cunningham-Rundles C, Pahwa S. Chronic fatigue syndrome: a working case definition. Ann Intern Med. 1988;108:387-389.[PubMed] [DOI] ↩
- Fukuda K, Straus SE, Hickie I, Sharpe MC, Dobbins JG, Komaroff A. The chronic fatigue syndrome: a comprehensive approach to its definition and study. International Chronic Fatigue Syndrome Study Group. Ann Intern Med. 1994;121:953-959.[PubMed] [DOI] ↩
- Jason LA, Jessen T, Porter N, Boulton A, Njoku MG, Friedberg F. Examining types of fatigue among individuals with ME/CFS (DSQ 2009; 29). [Full Text] ↩
- Jason LA, Boulton A, Porter NS, Jessen T, Njoku MG, Friedberg F. Classification of myalgic encephalomyelitis/chronic fatigue syndrome by types of fatigue. Behav Med. 2010;36:24-31.[PubMed] [DOI] ↩
- Jason LA, Torres-Harding SR, Carrico AW, Taylor RR. Symptom occurrence in persons with chronic fatigue syndrome. Biol Psychol. 2002;59:15-27.[PubMed] [DOI] ↩ ↩
- Wessely S. Chronic fatigue syndrome. Summary of a report of a joint committee of the Royal Colleges of Physicians, Psychiatrists and General Practitioners. J R Coll Physicians Lond. 1996;30:497-504.[PubMed] ↩
- Lane RJ, Barrett MC, Taylor DJ, Kemp GJ, Lodi R. Heterogeneity in chronic fatigue syndrome: evidence from magnetic resonance spectroscopy of muscle. Neuromuscul Disord. 1998;8:204-209.[PubMed] [DOI] ↩
- Aslakson E, Vollmer-Conna U, Reeves WC, White PD. Replication of an empirical approach to delineate the heterogeneity of chronic unexplained fatigue. Popul Health Metr. 2009;7:17.[PubMed] [Full Text] ↩
- Wilson A, Hickie I, Hadzi-Pavlovic D, Wakefield D, Parker G, Straus SE, Dale J, McCluskey D, Hinds G, Brickman A. What is chronic fatigue syndrome? Heterogeneity within an international multicentre study. Aust N Z J Psychiatry. 2001;35:520-527.[PubMed] [DOI] ↩
- Ramsay AM. Encephalomyelitis in North West London. A disease simulating poliomyelitis and hysteria. Lancet 1957; 2: 1196-1200. ↩
- Ramsay MA. Myalgic encephalomyelitis and postviral fatigue states: The saga of royal free disease. 2nd ed. Gower; London, UK: 1988. [Exerpt] ↩
- Hyde BM, Goldstein JA, Levine P. The clinical and scientific basis of myalgic encephalomyelitis/chronic fatigue syndrome. Nightingale research foundation; Ottawa, ON: 1992. ↩
- Ramsay, A.M. & Dowsett, B. (1992) Myalgic encephalomyelitis, then and now, and epidemiological introduction. In B.M. Hyde, J. Goldstein & P. Levine (Eds.), The clinical and scientific basis of myalgic encephalomyelitis/chronic fatigue syndrome (pp. 81-84). Ottawa: Nightingale Research Foundation. ↩
- Holmes GP, Kaplan JE, Gantz NM, Komaroff AL, Schonberger LB, Straus SE, et al. Chronic Fatigue Syndrome: A Working Case Definition. Ann Intern Med. 1988;108:387-389. doi:10.7326/0003-4819-108-3-387. [PubMed] [Full Text] ↩
- Katon W, Russo J. Chronic fatigue syndrome criteria. A critique of the requirement for multiple physical complaints. Archives of Internal Medicine. 152:1604–1609.doi:10.1300/J092v13n02_01. [PubMed] ↩
- Sharpe MC, Archard LC, Banatvala JE, et al. A report–chronic fatigue syndrome: guidelines for research. Journal of the Royal Society of Medicine. 1991;84(2):118-121. [PubMed], [Full Text] ↩ ↩
- Wyller, VB. The chronic fatigue syndrome–an update. Acta neurologica Scandinavica. Supplementum, 2007, 187: 7–14. doi:10.1111/j.1600-0404.2007.00840.x. PMID 17419822 [PubMed] ↩
- White PD, Goldsmith KA, Johnson AL, Potts L, Walwyn R, DeCesare JC, Baber HL, Burgess M, Clark LV, Cox DL, Bavinton J, Angus BJ, Murphy G, Murphy M, O’Dowd H, Wilks D, McCrone P, Chalder T, Sharpe M; PACE trial management group. Comparison of adaptive pacing therapy, cognitive behaviour therapy, graded exercise therapy, and specialist medical care for chronic fatigue syndrome (PACE): a randomised trial. Lancet. 2011 Mar 5;377(9768):823-36. doi: 10.1016/S0140-6736(11)60096-2. Epub 2011 Feb 18. [PubMed], [Full Text] ↩
- Twisk FN, Maes M. A review on cognitive behavorial therapy (CBT) and graded exercise therapy (GET) in myalgic encephalomyelitis (ME) / chronic fatigue syndrome (CFS): CBT/GET is not only ineffective and not evidence-based, but also potentially harmful for many patients with ME/CFS. Neuro Endocrinol Lett. 2009;30(3):284-99. [PubMed], [Full Text] ↩
- David AS (1991) Postviral syndrome and psychiatry. Br Med Bull. 47: 966–988. ↩
- David AS (1991) Postviral syndrome and psychiatry. Br Med Bull. 47: 966–988. ↩
- Jason LA, Brown A, Clyne E, Bartgis L, Evans M, Brown M. Contrasting Case Definitions for Chronic Fatigue Syndrome, Myalgic Encephalomyelitis/Chronic Fatigue Syndrome and Myalgic Encephalomyelitis. Evaluation & the health professions. 2012;35(3):280-304. doi:10.1177/0163278711424281. [Full Text] ↩
- Carruthers, B. M., van de Sande, M. I., De Meirleir, K. L., Klimas, N. G., Broderick, G., Mitchell, T., Staines, D., Powles, A. C. P., Speight, N., Vallings, R., Bateman, L., Baumgarten-Austrheim, B., Bell, D. S., Carlo-Stella, N., Chia, J., Darragh, A., Jo, D., Lewis, D., Light, A. R., Marshall-Gradisbik, S., Mena, I., Mikovits, J. A., Miwa, K., Murovska, M., Pall, M. L. and Stevens, S. (2011), Myalgic encephalomyelitis: International Consensus Criteria. Journal of Internal Medicine, 270: 327–338. doi: 10.1111/j.1365-2796.2011.02428.x. [PubMed], [Full Text] ↩
- Morris G, Maes M. Case definitions and diagnostic criteria for Myalgic Encephalomyelitis and Chronic fatigue Syndrome: from clinical-consensus to evidence-based case definitions. Neuro Endocrinol Lett. 2013;34(3):185-99. [PubMed], [Full Text] ↩
- Leonard A. Jason, Susan R. Torres-Harding, Renee R. Taylor, Adam W. Carrico, A Comparison of the 1988 and 1994 Diagnostic Criteria for Chronic Fatigue Syndrome. Journal of Clinical Psychology in Medical Settings, 2001. Vol. 8, No. 4, pp 337-343. [Abstract] [Full Text] ↩ ↩
- Jason LA, Richman JA, Rademaker AW, Jordan KM, Plioplys AV, Taylor RR, McCready W, Huang CF, Plioplys S., A community-based study of chronic fatigue syndrome. Arch Intern Med. 1999 Oct 11;159(18):2129-37. [PubMed] ↩
- Wessely S, Chalder T, Hirsch S, Wallace P, Wright D., The prevalence and morbidity of chronic fatigue and chronic fatigue syndrome: a prospective primary care study. Am J Public Health. 1997 Sep;87(9):1449-55. [PubMed] ↩
- Tiersky LA, Weisberg S, Zhang QW et al. Symptom frequency and severity in chronic fatigue syndrome. 2000. Unpublished manuscript. ↩
- Williams, Margaret. Ellen Goudsmit PhD and the “London” criteria : THE FACTS. MEActionUK, 2005. [article] ↩
- EG Dowsett, E Goudsmit, A Macintyre, C Shepherd, et al., London criteria for M.E., Report from The National Task Force on Chronic Fatigue Syndrome (CFS), Post Viral Fatigue Syndrome (PVFS), Myalgic Encephalomyelitis (ME). Westcare, 1994, pp. 96-98. [name-us.org] ↩
- Shepherd, C. London Criteria for M.E. – for website discussion. ME Association, 2011, [Article] ↩
- Carruthers, et al., ME/CFS: Clinical Working Case Definition, Diagnostic and Treatment Protocols, Journal of Chronic Fatigue Syndrome, Volume 11, Number 1 2003. Page 18-126. [Overview], [Full Report] ↩
- Jason, L.A., M. Evans, N. Porter, M. Brown and A. Brown et al., 2010. The Development of a Revised Canadian Myalgic Encephalomyelitis Chronic Fatigue Syndrome Case Definition. Am. J. Biochem. Biotechnol., 6: 120-135. [Abstract], [Full Text] ↩
- Reeves WC, Wagner D, Nisenbaum R, et al. Chronic Fatigue Syndrome – A clinically empirical approach to its definition and study. BMC Medicine. 2005;3:19. doi:10.1186/1741-7015-3-19. [Full Text] ↩
- Jason, Leonard A; Najar, Natasha; Porter, Nicole; Reh, Christy (2009). “Evaluating the Centers for Disease Control’s Empirical Chronic Fatigue Syndrome Case Definition“. Journal of Disability Policy Studies 20 (2): 93–100. doi:10.1177/1044207308325995. [Abstract], [Full Text] ↩
- Jason L., Evans M., Brown A., Brown M., Porter N., Hunnell J., Anderson V. & Lerch A. (2010). Sensitivity and Specificity of the CDC Empirical Chronic Fatigue Syndrome Case Definition. Psychology, 1, 9-16. doi: 10.4236/psych.2010.11002. [Abstract] ↩
- Reeves WC, Jones JF, Maloney E, et al. Prevalence of chronic fatigue syndrome in metropolitan, urban, and rural Georgia. Popul Health Metr 2007;5:5. [Full Text] ↩
- Jason LA, Najar N, Porter N, et al. Evaluating the Centers for Disease Control’s empirical chronic fatigue syndrome case definition. J Disabil Policy Stud 2009;20:93–100. [Abstract], [Full Text] ↩
- Jason, L. Sunnquist, M. Brown, A. McManimen, S. Furst, J. Reflections on the IOM’s systemic exertion intolerance disease. Pol Arch Med Wewn 2015 pii: AOP_15_067 [Abstract], [Full Text] ↩ ↩
- Jason, L.A.; Sunnquist, M.; Kot, B.; Brown, A. Unintended Consequences of not Specifying Exclusionary Illnesses for Systemic Exertion Intolerance Disease. Diagnostics 2015, 5, 272-286. [Abstract], [Full Text] ↩ ↩