Definition: Chronic fatigue syndrome is characterised by severe, disabling fatigue and other symptoms, including musculoskeletal pain, sleep disturbance, impaired concentration, and headaches. Two widely used definitions of chronic fatigue syndrome (from the US Centers for Disease Control and Prevention 1 and from Oxford 2—see table) were developed as operational criteria for research. There are two important differences between these definitions. The British criteria insist on the presence of mental fatigue; the American criteria include a requirement for several physical symptoms, reflecting the belief that chronic fatigue syndrome has an underlying immunological or infective pathology.
Incidence/prevalence: Community and primary care based studies have reported the prevalence of chronic fatigue syndrome to be 0.2-2.6%, depending on the criteria used.3 4 Systematic population surveys have found similar rates of the syndrome in people of different socioeconomic status, and in all ethnic groups.4 5 Female sex is the only demographic risk factor (relative risk 1.3 to 1.7 depending on diagnostic criteria used).6
Aetiology: The cause of chronic fatigue syndrome is poorly understood.
Prognosis: Studies of prognosis in chronic fatigue syndrome have focused on people attending specialist clinics, who are likely to have had the condition for longer and to have a poorer outlook. Children with the syndrome seem to have a notably better outcome: 54-94% of children show definite improvement (after up to six years’ follow up); 20-50% of adults show some improvement in the medium term and only 6% return to premorbid levels of functioning.7 Despite the considerable burden of morbidity associated with chronic fatigue syndrome, there is no evidence of increased mortality. Outcome is influenced by the presence of psychiatric disorders and beliefs about causation and treatment.7
Aims: To reduce levels of fatigue and associated symptoms; to increase levels of activity; to improve quality of life.
Outcomes: Severity of symptoms; effects on physical function and quality of life measured in several different ways by: the medical outcomes survey short form general health survey (SF-36), a rating scale measuring limitation of physical functioning caused by ill health 8; the Karnofsky scale, a modified questionnaire originally developed for the rating of quality of life in people undergoing chemotherapy for malignancy 9; the Beck depression inventory 10; the sickness impact profile, a measure of the influence of symptoms on social and physical functioning 11; and self reported severity of symptoms and levels of activity.
You can read the rest of this article here: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1117488/
Source: Reid S, Chalder T, Cleare A, Hotopf M, Wessely S. Chronic fatigue syndrome. BMJ : British Medical Journal. 2000;320(7230):292-296. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1117488/ (Full article)