Tom Kindlon 0

CDC CFS research should not involve the empirical definition (2005)

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(See below for extra commentary and information on the campaign. Apologies about the spacing)


Petition Text:

We call on the Centers for Disease Control and Prevention (CDC) to stop using the "empirical" definition[1] (also known as the Reeves 2005 definition) to define Chronic Fatigue Syndrome (CFS) patients in CFS research.

The CDC claim it is simply a way of operationalizing the Fukuda (1994) definition[2]. However the prevalence rates suggest otherwise: the "empirical" definition gives a prevalence rate of 2.54% of the adult population[3] compared to 0.235% (95% confidence interval, 0.142%-0.327%) and 0.422% (95% confidence interval, 0.29%-0.56%) when the Fukuda definition was used in previous population studies in the US[4,5].

The definition lacks specificity. For example, one research study[6] found that 38% of those with a diagnosis of a Major Depressive Disorder were misclassified as having CFS using the empirical/Reeves definition.


[1] Reeves WC, Wagner D, Nisenbaum R, Jones JF, Gurbaxani B, Solomon L, Papanicolaou DA, Unger ER, Vernon SD, Heim C. Chronic fatigue syndrome--a clinically empirical approach to its definition and study. BMC Med. 2005 Dec 15;3:19. Link:

[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. Ann Int Med 1994, 121:953-959.

[3] Reeves WC, Jones JF, Maloney E, Heim C, Hoaglin DC, Boneva RS, Morrissey M, Devlin R. Prevalence of chronic fatigue syndrome in metropolitan, urban, and rural Georgia. Popul Health Metr. 2007 Jun 8;5:5.

[4] Reyes M, Nisenbaum R, Hoaglin DC, Unger ER, Emmons C, Randall B, Stewart JA, Abbey S, Jones JF, Gantz N, Minden S, Reeves WC: Prevalence and incidence of chronic fatigue syndrome in Wichita, Kansas. Arch Int Med 2003, 163:1530-1536.

[5] 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.

[6] Jason, LA, Najar N, Porter N, Reh C. Evaluating the Centers for Disease Control's empirical chronic fatigue syndrome case definition. Journal of Disability Policy Studies 2008, doi:10.1177/1044207308325995. Further reading: Problems with the New CDC CFS Prevalence Estimates Leonard Jason, Ph.D., DePaul University i.e.

***Check blog for updates on the campaign (through August 2010) ***

Brief comment from Tom Kindlon (aka "rationale"):

I have Chronic Fatigue Syndrome (CFS) for over 20 years. I want a lot of research progress in my lifetime and believe the empirical definition* (Reeves et al., 2005)decreases the chances that this will occur: abnormalities that would show up using a more strictly defined definition won't show up using the empirical/Reeves definition; and abnormalities that might show up in the broad group covered by the empirical/Reeves definition are not necessarily representative of CFS patients.

Similarly treatments that might work on a more strictly defined group of patients might not show up using the very broad empirical/Reeves definition and treatments that might appear to work overall on the group defined using the empirical/Reeves definition might not be suitable for people who satisfy a stricter definition.

This messes up the CFS literature even further.

* It has also been called the Reeves definition (2005)



This petition was set up on April 15, 2009. The short-term goal was to mention it in submissions in April/May 2009 on the CDC's CFSplans. It wasenvisaged it would remain as long as the CDC continued to use the definition.


August 2010:


Ideally,a minimum of 2500 signatures on the petition before the fall 2010 Chronic Fatigue Syndrome Advisory Committee (CFSAC) committee meeting. The date for the meeting has not yet been posted. It is normally in October, but may be in September this year.

-- Technical note: I am not sure why some people have grey boxes in the comments section. [(Update June 18, 2009) One person (thanks Greg) contacted support and was told that quotation marks (he is not sure if that is both single and double i.e. ' and ") can cause problems so it may be best to leave these out]. The problem does not seem to be related to whether people donate to or not.

If your comment isn't visible, feel free to contact me at, giving the current number of your signature, and I'll be happy to delete your signature and for you to try again to sign and write a comment.


Tom Kindlon, a patient with Chronic Fatigue Syndrome (CFS) for over 20 years. I have done a lot of voluntary work in the area for over a decade. Recently I had 11 letters on CFS published in peer-reviewed medical journals [Archives of Physical Medicine and Rehabilitation, British Medical Journal (x2), Brain, Bulletin of the IACFS/ME, Journal of Rehabilitation Medicine (with Dr. EM Goudsmit), Pain Medicine, Psychological Medicine, Psychosomatic Medicine, Psychotherapy and Psychosomatics and the Lancet]. (The letter published in June 2010 edition of Psychosomatic Medicine lists many of my concerns - reference: Kindlon T. Criteria Used To Define Chronic Fatigue Syndrome Questioned. Psychosom Med 2010 72: 506-507). I also had a full paper published in the peer-reviewed journal, Bulletin of the IACFS/ME.


The paper defining the empirical/Reeves definition can be read at:


Some comments on the paper have been posted at:  


An article by Leonard Jason PhD on the issue can be read at:  i.e.


Jason, LA, Najar N, Porter N, Reh C. Evaluating the Centers for Disease Control's empirical chronic fatigue syndrome case definition. Journal of Disability Policy Studies 2008, doi:10.1177/1044207308325995.


Jason LA, Evans M, Brown A, Porter N, Hunnell J, Anderson V, Lerch A. Sensitivity and Specificity of the CDC Empirical Chronic Fatigue Syndrome Case Definition. Psychology, 2010, 1: 9-16, doi:10.4236/psych.2010.11002.

Full free text:


"Defining CFS: The Debate Goes On" - article by the CAA explaining Dr Jason's study in layman's terms. It also includes some other comments on the criteria.


"How Science Can Stigmatize: The Case of Chronic Fatigue Syndrome" by Leonard A. Jason, PhD and Judith A. Richman, PhD Empiric criteria (Reeves, 2005) and CFS: what do we know about the percentage of CFS (empirc) patients who would satisfy the Fukuda definition from random number population studies in the US:


Recording of CAA webinar (April 14, 2010) by Leonard Jason    , "Defining CFS: Diagnostic Criteria and Case Definitions" (includes discussion of empiric criteria): or   Program slides:


Measuring substantial reductions in functioning in patients with chronic fatigue syndrome.

Jason L, Brown M, Evans M, Anderson V, Lerch A, Brown A, Hunnell J, Porter N.
Disabil Rehabil. 2010 Jul 9. [Epub ahead of print] 


Amongst other things, this study using the empiric(al) definition shows that one can satisfy the definition even when one scores 100 out of 100 on the physical functioning subscale of the SF-36:

Switzer WM, Jia H, Hohn O, Zheng H, Tang S, Shankar A, Bannert N, Simmons G, Hendry RM, Falkenberg VR, Reeves WC, Heneine W.

Absence of evidence of xenotropic murine leukemia virus-related virus infection in persons with chronic fatigue syndrome and healthy controls in the United States.

Retrovirology. 2010 Jul 1;7:57. By Kasper Ezelius M.Sc. This includes some links to other definitions, Kasper's take on the issues and a list of some papers that have involved using the empirical definition (this list is not up-to-date; virtually all the papers from the CDC 2-day Wichita study and also from the Georgia cohort have used the empirical definition to define CFS)



Dr. Mary Schweitzer's piece, "CFS Research on CFS: Open Deception" 


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