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"Criterion
variance is likely to occur when explicit criteria do not exist
for diagnostic categories. For example the US case
definition of CFS treats two central symptoms, post-exertional
malaise and cognitive impairment, as optional rather than required
criteria."
-Jason, Taylor, Song, Kennedy, Johnson-
"Do not for one minute believe that
CFS is simply another name for Myalgic Encephalomyelitis (M.E.).
It is not. Though CFS is based upon a typical M.E. epidemic,
in my opinion it has always been a confused and distorted view of
reality.
The invention of Chronic Fatigue Syndrome has to be one of the
most curious cases of inventive American imperialism that one
could imagine."
-Dr. Byron Hyde -
The first CFS definition
(Holmes, CDC USA, 1988) was invented during an outbreak of what
can only be described as distinct ME in Nevada at Lake Tahoe in
the mid-1980s. (See
note on Dr. Hyde's page.) Various sources will say that the the renaming of ME was either deliberate for political and insurance purposes,
or just a bungle of bureaucracy, or perhaps both. Either
way, it ignited an ongoing controversy that has lasted to the
present, bogging down research and delaying discovery of effective
treatments while patients linger - debilitated, declining and dying
fairly young (see
Mortality) after years of chronic illness. Two Australian CFS definitions appeared shortly
after the US definition (Lloyd et al, 1988,
1990), and another came out of Great Britain (Oxford, 1991).
(See sidebar for links to summaries of
these and other definitions.)
All of these definitions
focused on fatigue, and did/do not exclude psychiatric illness as
a cause of the fatigue.
The Centers for Disease Control
revised the 1988 CFS definition in 1994 (Fukuda,
1994). It is currently in use for research
and clinical diagnosis in the US and most countries abroad. That
these definitions were prepared by government bureaucrats, rather
than by physicians who had collectively seen, studied and treated
thousands of patients with the illness, is testimony to their validity (or lack thereof).
Dr. Nancy Klimas from the University of Miami School of Medicine
and long-time researcher into immune abnormalities in ME and CFS,
commented on the revised 1994 definition: "...the resulting
guidelines are rife with ambiguity. Symptoms are counted
either as present or absent, without regard to severity or
frequency." (See below 4
research articles that study the flaws in this definition.)
A major
complaint researchers and patients have with this definition is
that it is broad and unspecific, and focuses on a single
symptom--fatigue. There are many diseases that can cause
debilitating fatigue, including psychological illnesses, that may not be covered by the CDC's list of
exclusionary diseases in this definition. Thus, a patient
diagnosed with CFS may have some other underlying condition that
doctors failed to detect. Dr. Byron Hyde makes this very
clear in
The Complexities of Diagnosis, while Dr. E.G. Dowsett states
in
A Rose By Any Other Name
that the CDC definitions "elevated tonsillitis, glandular
enlargement and fatigue to unreal importance while overlooking the
characteristic encephalitic features of the genuine disease."
From the
CDC website on chronic fatigue syndrome:
Chronic
fatigue syndrome, or CFS, is a debilitating and complex disorder
characterized by profound fatigue that is not improved by bed rest
and that may be worsened by physical or mental activity. Persons
with CFS most often function at a substantially lower level of
activity than they were capable of before the onset of illness. In
addition to these key defining characteristics, patients report
various nonspecific symptoms, including weakness, muscle pain,
impaired memory and/or mental concentration, insomnia, and post-exertional
fatigue lasting more than 24 hours. In some cases, CFS can persist
for years. The cause or causes of CFS have not been identified and
no specific diagnostic tests are available. Moreover, since many
illnesses have incapacitating fatigue as a symptom, care must be
taken to exclude other known and often treatable conditions before
a diagnosis of CFS is made.
Definition of CFS
A great deal of debate has surrounded the issue of how best to
define CFS. In an effort to resolve these issues, an international
panel of CFS research experts convened in 1994 to draft a
definition of CFS that would be useful both to researchers
studying the illness and to clinicians diagnosing it. In essence,
in order to receive a diagnosis of chronic fatigue syndrome, a
patient must satisfy two criteria:
-
Have
severe chronic fatigue of six months or longer duration with
other known medical conditions excluded by clinical diagnosis;
and
-
Concurrently have four or more of the following symptoms:
substantial impairment in short-term memory or concentration;
sore throat; tender lymph nodes; muscle pain; multi-joint pain
without swelling or redness; headaches of a new type, pattern or
severity; unrefreshing sleep; and post-exertional malaise
lasting more than 24 hours.
The symptoms
must have persisted or recurred during six or more consecutive
months of illness and must not have predated the fatigue.
[Click here for the complete CDC [Fukuda, 1994] CFS Case Definition.]
Four studies from two separate research
groups demonstrate the need to revise or replace this definition:
 Chronic
fatigue syndrome: The need for subtypes.
Jason, L.A., Corradi, K., Torres-Harding, S., Taylor, R.R., &
King, C. (2005). Neuropsychology Review, 15, 29-58. "The
current U.S. case definition for CFS (Fukuda et al., 1994) is
characterized by vaguely worded criteria that lack operations
definition and guidelines to assist health care professional in
their interpretation and application of the diagnostic too. (Jason
et al., 1999d). The Canadian case definition [includes]
these critical symptoms and use of such types of case definitions
might aid in the selection of more homogeneous samples. Based on
the research reviewed in this section, we would encourage
researchers to compare and contrast categories of patients meeting
the Canadian Case definition and the Fukuda et al. (1994)
criteria. In addition, the provision of standardized measures for
assessment and scoring guidelines should reduce clinicians’
difficulty with the criteria and their need to modify the criteria
in clinical practice. In effect, the use of standardized measures
should reduce criterion variance and improve diagnostic
reliability (King and Jason, 2004)."
(Abstract and summary only)
Comparing
the Fukuda et al. criteria and the Canadian case definition for
chronic fatigue syndrome.
Jason, L.A., Torres-Harding, S.R., Jurgens, A., & Helgerson, J.
(2004). Journal of Chronic
Fatigue Syndrome, 12, 37-52. "...those individuals in
this study meeting the Canadian criteria appear to have more
symptoms, more physical functional impairment, and less
psychopathology than those in the CF-psychiatric group. In
addition, the Canadian criteria identifies patients with more
fatigue/weakness, neurological and neuropsychiatric symptoms than
the Fukuda CFS criteria does."
The
specificity of the CDC-1994 criteria for chronic fatigue syndrome:
comparison of health status in three groups of patients who fulfil
the criteria. (Abstract) Kennedy G, Abbot NC, Spence V,
Underwood C, Belch JJF Institution: Vascular Diseases Research
Unit, Department of Medicine, University of Dundee. "Aim:
The Centers for Disease Control (CDC)-1994 definition of chronic
fatigue syndrome (CFS) is very broad, and there have been
suggestions that it lacks specificity. Conclusions: Differences in
simple, easily performed clinical outcome measurements can be
observed between groups of patients, all of whom fulfill the
CDC-1994 criteria for CFS. It is likely that their response to
treatment may also vary. The specificity of the CFS case
definition should be improved to define more homogeneous groups of
patients for the purposes of treatment and research."
Politics,
science, and the emergence of a new disease: The case of Chronic
Fatigue Syndrome. (Abstract)
Jason, L.A., Richman, J.A., Friedberg, F., Wagner, L., Taylor, R.,
& Jordan, K.M. (1997). American
Psychologist, 52, 973-983. "Many physicians minimized the
seriousness of this disorder and also interpreted the syndrome as
being equivalent to a psychiatric disorder. These attitudes had
negative consequences for the treatment of CFS."
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