The Fukuda Definition was developed by the CDC in 1994 primarily for research studies of CFS in adults, but has also been used clinically.
Note, the definition does not acknowledge Myalgic Encephalomyelitis (ME) as defined by WHO.
The Fukuda Definition is widely criticised by ME/CFS researchers, clinicians and patient groups because it focuses primarily on fatigue and downplays the importance of other core symptoms of ME/CFS. (See Criticisms of Fukuda below)
Fukuda is the less specific than the ICC and CCC definitions.
Keiji Fukuda, M.D., M.P.H., Stephen E. Straus, M.D., Ian Hickie, M.D., F.R.A.N.Z.C.P., Michael C. Sharpe, M.R.C.P., M.R.C. Psych., James G. Dobbins, Ph.D., Anthony L. Komaroff, M.D., F.A.C.P. and the International Chronic Fatigue Syndrome Study Group
- CDC case definition (1994)
- International definition (1994)
- 1994 Case Definition
A case of the chronic fatigue syndrome is defined by the presence of the following:
- Clinically evaluated, unexplained, persistent or relapsing chronic fatigue that is of new or definite onset [has not been lifelong]; is not the result of ongoing exertion; is not substantially alleviated by rest; and results in substantial reduction in previous levels of occupational, educational, social, or personal activities, and
- The concurrent occurrence of four or more of the following symptoms, all of which must have persisted or recurred during 6 or more consecutive months of illness and must not have predated the fatigue.
- 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
- Multijoint pain without joint swelling or redness
- Headaches of a new type, pattern, or severity
- Unrefreshing sleep
- Postexertional malaise lasting more than 24 hours.
A case of idiopathic chronic fatigue is defined as clinically evaluated, unexplained chronic fatigue that fails to meet criteria for the chronic fatigue syndrome.
Conditions that Exclude a Diagnosis of CFS
- Any active medical condition that may explain the presence of chronic fatigue, such as untreated hypothyroidism, sleep apnea, and narcolepsy, and iatrogenic conditions such as side effects of medication.
- Any previously diagnosed medical condition whose resolution has not been documented beyond reasonable clinical doubt and whose continued activity may explain the chronic fatiguing illness. Such conditions may include previously treated malignancies and unresolved cases of hepatitis B or C virus infection.
- Any past or current diagnosis of a major depressive disorder with psychotic or melancholic features; bipolar affective disorders; schizophrenia of any subtype; delusional disorders of any subtype; dementias of any subtype; anorexia nervosa; or bulimia nervosa.
- Alcohol or other substance abuse within 2 years before the onset of the chronic fatigue and at any time afterward.
Severe obesity [32, 33] as defined by a body mass index (body mass index = weight in kilograms/[height in meters]2) ≥ 45.
Conditions that do not Exclude a Diagnosis of CFS
- Any condition defined primarily by symptoms that cannot be confirmed by diagnostic laboratory tests, including fibromyalgia, anxiety disorders, somatoform disorders, nonpsychotic or nonmelancholic depression, neurasthenia, and multiple chemical sensitivity disorder.
- Any condition under specific treatment sufficient to alleviate all symptoms related to that condition and for which the adequacy of treatment has been documented. Such conditions include hypothyroidism for which the adequacy of replacement hormone has been verified by normal thyroid-stimulating hormone levels or asthma in which the adequacy of treatment has been determined by pulmonary function and other testing.
- Any condition, such as Lyme disease or syphilis, that was treated with definitive therapy before development of chronic symptomatic sequelae.
- Any isolated and unexplained physical examination finding or laboratory or imaging test abnormality that is insufficient to strongly suggest the existence of an exclusionary condition. Such conditions include an elevated antinuclear antibody titer that is inadequate to strongly support a diagnosis of a discrete connective tissue disorder without other laboratory or clinical evidence.
- Any unexplained physical examination finding or laboratory or imaging test abnormality that strongly suggests the presence of an exclusionary condition must be resolved before further classification.
Criticisms of Fukuda
One of the main criticisms of Fukuda is that it waters down the disease entity ME as defined by WHO to what is basically ‘fatigue’. As a result, Fukuda devalues the seriousness of other non-fatigue symptoms and of the illness.
In the Fukuda definition fatigue is the only compulsory symptom, with four other symptoms being required out of a list of eight: impaired short term memory or concentration; sore throat; tender cervical or axilliary (armpit) lymph nodes; muscle pain; multi-joint pain without arthritis; headaches of a new type, pattern, or severity; unrefreshing sleep; post-exertional malaise lasting more than 24 hours.
Using the Fukuda definition it is possible for someone to be diagnosed with CFS without experiencing, for example, post-exertional malaise, unrefreshing sleep or cognitive problems. The result is that the Fukuda definition tends to select people with a wide range of “fatiguing illnesses”, including depressive disorders and not only people with ME/CFS.
This has had long-lasting ramifications for patient selections for research purposes and allocation of funding.
- Fukuda K, Straus SE, Hickie I, Sharpe MC, Dobbins JG, Komaroff A. (1994) The chronic fatigue syndrome – a comprehensive approach to its definition and study. (Fukuda definition) Annals of Internal Medicine 1994, 121:953-959. [PubMed]
- Fukuda K, Straus SE, Hickie I, Sharpe MC, Dobbins JG, Komaroff A. (1994) The chronic fatigue syndrome – a comprehensive approach to its definition and study. (Fukuda definition) Annals of Internal Medicine 1994, 121:953-959. [Full text]