The Oxford Definition It's Baaack

I asked CDC's Unger via email why is CDC using the antiquated Oxford* definition in its partnership with HRSA (Health Resources and Services Administration), along with Fukuda** and Canadian Consensus Criteria*** in its continuing education courses? The Oxford definition requires only fatigue, unlike the other definitions of ME, which require immune, neurologic and autonomic symptoms.

I also asked Unger:

• For most CFS-literate physicians and patients, using all three definitions is a problem. That’s because the Oxford definition requires only fatigue as a symptom. In contrast, Fukuda requires fatigue and four other symptoms.* According to most CFS-literate physicians, the Canadian Consensus Criteria (CCC) is the most accurate and thorough of these three definitions, and requires the following: fatigue, post-exertional malaise and/or fatigue, sleep dysfunction, and pain; two or more neurological/cognitive manifestations and one or more symptoms from two of the categories of autonomic, neuroendocrine and immune manifestations.**

Given the significant differences in definitions, does CDC believe using all three definitions is problematic?  Why or why not?

• By focusing on fatigue, the Oxford definition neglects other important symptoms embraced by CCC, as well as other symptoms in the original Fukuda definition. Fatigue is characteristic of many illnesses, from cancer and heart disease to depression.  Thus, with the Oxford definition, CFS morphs into a vague disease—it’s only vague by the Oxford definition, not by CCC.  Using the Oxford definition makes it more difficult for doctors to distinguish pathological fatigue of CFS from ordinary fatigue and from illnesses that have fatigue as a symptom—and that’s most illnesses. For all these reasons, Oxford is, in the view of most patients and CFS-literate physicians, a woefully inadequate and inaccurate definition.  Does CDC understand the problems with the Oxford definition?

• Does CDC want there to be confusion about the disease?  

• If CDC doesn’t want there to be confusion, why does it use all three vastly different definitions in the HRSA CME courses?

• Over and over again, CDC states in meetings and in its medical articles that CFS is a poorly understood disease. Other researchers and clinicians look to CDC for guidance. Does CDC understand that by using all three of these vastly different definitions, CDC is causing the disease to be poorly understood?

• The CCC definition describes the illness that most patients and CFS-literate physicians understand to be CFS. Given that using multiple definitions results in confusion and heterogeneous populations, why not make this critical change and use only CCC? Please explain why CDC won’t do this.

CDC’s Response
Through its press office, CDC—I assume it was Unger, since I directed my questions to her—replied:

CDC has developed several CFS CME courses, including Diagnosis and Management of Chronic Fatigue Syndrome (see http://www.cdc.gov/cfs/education/diagnosis/index.html) which was prepared in collaboration with other CFS subject matter experts, including non-CDC clinicians in private practice and academic settings. Among other things, this CDC CME course provides information about multiple CFS case definitions, such as those mentioned in your query. CDC uses the 1994 case definition, but recognizes there are additional case definitions that can be useful. CDC is committed to providing accurate, evidence-based CFS information that is relevant to various audiences, including CFS patients, clinicians who treat CFS patients, researchers, and others.
 
I believe this information addresses the questions you asked.  You may wish to contact HRSA directly about questions regarding CME courses produced by that agency.
 
Thank you for your interest in CDC’s CFS research program.

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*Oxford definition
fatigue as the main symptom; definite onset and not lifelong; fatigue is severe, disabling and affects physical and mental function; fatigue should persist for 6 months or more and be present 50% of the time; other symptoms, especially myalgia, sleep and mood disturbance may be present.

**Fukuda definition:
Patients must have four of the following:

Self-reported impairment in short term memory or concentration severe enough to cause substantial reduction in previous levels of occupational, educational, social, or personal activities; sore throat; tender cervical or axillary lymph nodes; muscle pain; multi-joint pain without swelling or redness; headaches of a new type, pattern or severity; unrefreshing sleep; post-exertional malaise (PEM) lasting more than 24 hours.


*** Canadian Consensus Criteria:
Neurological/Cognitive Manifestations: Two or more of the following: confusion, impairment of concentration and short-term memory consolidation, disorientation, difficulty within formation processing, categorizing and word retrieval, and perceptual and sensory disturbances—e.g., spatial instability and disorientation and inability to focus vision. Ataxia, muscle weakness and fasciculations are common. There may be overload phenomena: cognitive, sensory—e.g., photophobia and hypersensitivity to noise—and/or emotional overload, which may lead to crash periods and/or anxiety.

One or more symptoms from two of the categories of autonomic, neuroendocrine and immune manifestations:

Autonomic Manifestations: orthostatic intolerance neurally mediated hypotension (NMH), postural orthostatic tachycardia syndrome (POTS), delayed postural hypotension; light-headedness; extreme pallor; nausea and irritable bowel syndrome; urinary frequency and bladder dysfunction; palpitations with or without cardiac arrhythmias; exertional dyspnea.

Neuroendocrine Manifestations:  loss of thermostatic stability—subnormal body temperature and marked diurnal fluctuation, sweating episodes, recurrent feelings of feverishness and cold extremities; intolerance of extremes of heat and cold; marked weight change—anorexia or abnormal appetite; loss of adaptability and worsening of symptoms with stress.

Immune Manifestations: tender lymph nodes, recurrent sore throat, recurrent flu-like symptoms, general malaise, new sensitivities to food, medications and/or chemicals.