CDC empiric definition for CFS from 2005


Author: Kasper Ezelius, M.Sc., Örebro, Sweden, Northern Europe,

Date: September 28, 2009





CDC empiric definition 2005 - Protest against CDC using it 1

CDC empiric CFS definition 2005 - Flaws in scientific approach. 2

Suggestions for future Research. 3

References 4

Earlier documents of the same matter 4


CDC empiric definition 2005 - Protest against CDC using it

Knowing that the petition against the CDC uses the CFS-Reeves-2005 definition has been available since April 15, 2009, I am surprised that only around 1.700 have signed so far. The response from the international ME-community is lame. I would have expected around 17.000-170.000 instead of the few 1.700 signatures, knowing the worldwide number of people with ME. The petition text is simple "CDC CFS research should not involve the empirical definition (2005)", and I think nobody with ME could ever object to that. I wonder where all the US inhabitants with ME are? Why do so few sign? They should be very large in number - around a million.

I think the petition is important, and will be like a "burial stone" for lost research into ME. A historical document how CDC changed its course, and how the whole world cried out loud. A remainder for future generations of ME patients, to know that their predecessors really did protest against the "burial" of CDC sponsored biomedical research into ME. I hope the petition will stay on the web for ever in order to be a monument over lost voices, and lost hope for patients worldwide hoping for a cure from their prison of invalidity in their life-time.

Sign at the bottom of the page of the petition, then push the buttom "Sing petition". You are then taken to a new page with a text at the top that the signature was sucessfully registrered. On the same page you are urged to donate money to the site, but you can simply ignore that. Your signature will be registred anyhow.

Only sign once!

Sign Tom Kindlons petition "CDC CFS research should not involve the empirical definition (2005)" here:


CDC empiric CFS definition 2005 - Flaws in scientific approach

I have thought about how I would like to describe the flaws of the Reeves methodology, with statistics, math and reasoning, but I do not have the energy, but I will make a short summary below.

I would have thought that the scientific way to go, would be to create distributions in a multidimensional space of ME people in one set and the general population (healthy and sick, except ME) in the other set. Then I would have tried to create the largest distance for the points the multidimensional set of ME-people to the points in the set of the general population, in order to try to separate the two sets by a multidimensional plane. The location of the plane should be adjusted for the highest sensitivity and specificity.

I would have included physiological parameters and biomedical markers in a large amount in the multidimensional analysis, because ME is a physiological disease. I would also have tried to include more signs instead of only having symptoms.

Although, I am not sure I would ever have used the multidimensional approach for defining ME. Finally, it is what we put in the set of ME patients (for the multidimensional study) that defines the disease. Therefore, one can simply use the original definition for ME to define what is ME. Why go cross the river to get water?

I would have required post-exertional malaise to be present in a ME/CFS-definition. Post-exertional malaise should be present as a symptom, but also measured by objective test. The research is more and more showing a clear picture that post-exertional malaise lasting for 1-3 days, or more, is measurable by brain scans of blood flow, blood parameters (oxidative stress, ion channels, adrenergic receptors and immune molecules), and oxygen uptake for repeated exercise test. I think that a patient without post-exertional malaise, has a different pathophysiology and should be excluded from the ME-set. I also think that mental fog, that usually increases with upright posture, is a hallmark symptom.

What Reeves has done is to summarize a multidimensional space into ONE variable. This one-dimensional space is in simplified terms the sum of psychological and subjective symptoms. This means that an indefinite number of combinations of symptoms may score enough to be positive for CFS-Reeves-2005 (more appropriately labelled as "Reeves Illness Melange"), so one can expect that a multitude of symptom clusters exist in the mix of CFS-Reeves-2005. No clear picture of symptoms can be distinguished. It is such a big insult to scientific and logical thinking, that I can not believe that one of the worlds largest and most important agency, CDC, can be the part of it.

If a change of the CFS definition is made, it shall never be made over one night. One should use the new criteria in parallel with the old criteria during several years in order to keep comparability with research made with the old definition, and in order to validate the new definition. At this time the Canada-definition [1] is the most interesting candidate of replacing CFS-Fukuda in ME/CFS research. CFS-Fukuda does not require mandatory ME/CFS symptoms as for example post-exertional malaise lasting 1-3 days or more, it does not require mental fog. CFS-Fukuda is perceived as very vague by ME/CFS patients, while CFS-Canada-2003, is perceived as a very good description of their condition and something they can relate to.

Note: I would have spared the extensive multidimensional approach to try to find clusters and sub-groups within the ME-cohort.


Suggestions for future Research

I hope the scientific world will continue to study abnormalities in ME patients during post-exertional malaise. Many tests have been in the normal range, while one studied ME patients in in a state of rest, but when one studies what happens after exertion one really begins to discover that there are indeed abnormalities. The abonormalities are discovered in the dynamic response to exertion. I think this is the way to go. Scientists are discovering things that never has crossed their mind to test for several years. Biomedical and physiological findings are consistent with the patients reports of feeling awful after exertion. This direction of research should be continued and be extended into new areas of physiological and biomedical tests.

Because of the hijacking of the term CFS by Reeves and CDC, by replacing the already vague definition of CFS-Fukuda with the pot-pourri of CFS-Reeves, I think it is important for the scientitsts that use CFS-Fukuda to describe what kind of definition that has been used in the title of the scientific articles, otherwise things will start to be mixed up. I have no really good suggestion in how to do that. Maybe by referring to "CFS - Fukuda definition" in the title, while "chronic fatigue syndrome according to the Fukuda definition" will very long. If the Canadian definition is used one can maybe refer to "ME/CFS-Canada-2003" or "patients with ME/CFS according to the Canadian definition from 2003" in the title. The general reader will never understand that different definitions have been used unless it is clearly stated, and they will assume that all articles with "chronic fatigue syndrome" studies the same kind of patients, and this can make huge harm to the progress in scientific research into ME.

Hopefully more and more scientists will start to Use CFS-Fukuda and ME/CFS-Canada-2003 in paralell. The international biomedical research fund of "ME-föreningen" in Sweden requires so, and I hope more charities and research funds will start to do the same.




[1] Carruthers BM, Jain AK, De Meirleir KL, et al.

Myalgic encephalomyelitis/chronic fatigue syndrome: clinical working case definition, diagnostic and treatment protocols.

Journal of Chronic Fatigue Syndrome 2003;11:7–36.


[2] 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.


[3] Reeves WC, et al.

Chronic fatigue syndrome--a clinically empirical approach to its definition and study.

BMC Med. 2005 Dec 15;3:19.


Earlier documents of the same matter

In chronologic order


Use the Canadian criteria 2003 for CFS in the USA.

Kasper Ezelius. June 22, 2008:



Letter to the President and Congress of the United States of America, U.S. Department of Health and Human Services, U.S. National Institutes of Health, and U.S. Centers for Disease Control.



Resolution in order to make cohorts less heterogeneous.

Kasper Ezelius. 1st of September 2008:


Research into CFS (Chronic Fatigue Syndrome) and ME (Myalgic Encephalomyelitis) has been blurred through many decades due to heterogeneous patient populations (cohorts). One problem is that researchers, as well as clinicians, have different interpretations of what is CFS. Some researchers/clinicians would (incorrectly) not set a CDC CFS diagnosis if post-exertional malaise is not present, although the CDC CFS definition does not require post-exertional malaise.



How to categorize ME and CFS.

Kasper Ezelius. 23 October 2008:


This document is a brief sketch for further discussion on how to proceed with taxonomy in research related to Myalgic Encephalomyelitis (ME) and Chronic Fatigue Syndrome (CFS).



CFS is no longer CFS, and it was never ME.

Kasper Ezelius. 5 December 2008:


The Centres for Disease Control and Prevention in the USA has adopted a more including criterion for chronic fatigue syndrome which is important to be aware of when reading scientific papers. It is important to know that the new criteria is so much "loosened up" that it encompasses 2,5% of the general population instead of around 0,4% as with the earlier criteria. How to stratify and group patients in future research is proposed. The use of disjoint sets of patients is encouraged.






Copyright: ©Kasper Ezelius 2009

The text may be cited in whole or in part, if the author and title are mentioned, as well as a link to the original document.