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Steven Reid Guy's, Kings, and St Thomas's
School of Medicine and Institute of Psychiatry, London SE5 8AZ
Correspondence to: S
Reid steve.reid{at}kcl.ac.uk
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
Prevention1 and from Oxford2 Beneficial: Exercise Cognitive behavioural therapy Unknown effectiveness: Corticosteroids Antidepressants Dietary supplements Oral nicotinamide adenine dinucleotide (NADH) Unlikely to be beneficial: Immunotherapy Likely to be ineffective or harmful: Prolonged rest
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Background
Top
Background
Methods
References
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.
Interventions

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This review is one of 87 chapters
from the second issue of Clinical
Evidence www.evidence.org
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 health8; the Karnofsky scale, a modified questionnaire originally developed for the rating of quality of life in people undergoing chemotherapy for malignancy9; the Beck depression inventory10; the sickness impact profile, a measure of the influence of symptoms on social and physical functioning11; and self reported severity of symptoms and levels of activity.
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Summary points
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Methods |
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Clinical Evidence search and appraisal January 1999. All randomised controlled trials (RCTs) meeting Clinical Evidence criteria were reviewed. We found that the evidence on which to base clinical decisions was slender. Even where good evidence exists, there are likely to be large gaps in provision of services and expertise (for example, for cognitive behavioural therapies). Hence, for many practitioners it will be necessary to use clinical judgment linked with expertise derived from related areas, such as the management of chronic pain.
Question: What are the effects of treatments?
Option: Antidepressants
We found limited data from RCTs, providing insufficient evidence to support the use of antidepressants in people with chronic fatigue syndrome. However, research evidence suggests that antidepressants may be useful in treating associated depression, insomnia, or myalgia.
Benefits
We found no systematic reviews. Versus placebo:
We found three RCTs. One that compared fluoxetine with placebo in 96 people found no significant benefit on outcomes used (the Beck
depression inventory and the sickness impact profile).12 Another allocated 136 people to four groups: exercise plus
fluoxetine; exercise plus placebo; appointments to review activity
diary with physiotherapist plus fluoxetine, and appointments to review
activity diary with physiotherapist plus placebo. It found no
significant difference in outcome (level of fatigue), although there
was a trend indicating some benefit and there were modest improvements in measures of depression.13 The first study used shorter
treatment and studied people with a long duration of illness, which may explain the differing results. A third trial compared the monoamine oxidase inhibitor phenelzine versus placebo in 24 people with chronic
fatigue syndrome, using a modified Karnofsky scale and other outcome
measures.14 This also found a non-significant trend toward
improvement. Versus each other: We found one RCT comparing
sertraline with clomipramine in people with chronic fatigue syndrome,
but the lack of a placebo group makes it hard to draw useful
conclusions.15
Harms
Up to 15% of participants withdrew from active treatment because
of adverse drug effects.12-15
Comment
To date, clinical trials have taken place in specialist clinics,
which may actively select for people whose condition is more
resistant to treatment.
Benefits
We found no systematic review. Versus placebo: We
found three placebo controlled RCTs in people with chronic fatigue
syndrome. One, a crossover RCT of fludrocortisone in 20 people,
measured outcomes as change in symptom severity on a visual analogue
scale, and functional status (using the SF-36).16 It found
no significant difference between active treatment and placebo, though
the number of participants may have been too small to detect a
difference. The two other trials evaluated hydrocortisone. One compared
hydrocortisone 25-35 mg daily with placebo in 65 people and found a
greater improvement in a self rated scale of "wellness" in the
treatment group. However, other self rating scales did not show
significant benefit.17 The other study used a lower dose
of hydrocortisone (5 or 10 mg daily) in 32 people and found short term
improvement in fatigue. Nine people (28%) taking hydrocortisone improved, as measured by a self report fatigue scale, compared with
three (9%) taking placebo. The benefit rapidly attenuated when
treatment was stopped.18
Harms
The study using the higher doses of hydrocortisone found that 12 people (40%) receiving active treatment experienced adrenal
suppression.17 Minor adverse effects were reported in up
to 10% of people in the other studies.
16 18
Comment
The trials used different reasons for their choice of active
treatment. The use of fludrocortisone, a mineralocorticoid, was based
on the hypothesis that chronic fatigue syndrome is associated with
neurally mediated hypotension.19 The use of hydrocortisone in the other trials was based on evidence of underactivity of the
hypothalamic-pituitary-adrenocortical axis in some people with the
syndrome.20
Benefits
We found no systematic review. We found two RCTs. The first
compared aerobic exercise with flexibility training (control
intervention) in 66 people.21 The programmes involved individual weekly sessions over 12 weeks, with the exercise group building up their level of activity to 30 minutes exercise a day with a
maximum energy expenditure of 60% of maximum oxygen consumption (VO2 max). With the self rated clinical global
impression scales used as an outcome measure, 55% of the aerobic
exercise group reported feeling much better or very much better
compared with 27% of the flexibility training group (P=0.05).
Significantly better outcomes were also reported as measured by
physical fatigue and levels of physical functioning on the SF-36. The
flexibility training group crossed over to aerobic exercise at the end
of the trial, and significant improvements from baseline were found.
Harms
Adverse effects of exercise were not reported in either trial, and
we found no evidence that exercise is harmful in people with chronic
fatigue syndrome. However, experience suggests that exacerbation of
symptoms may result from overambitious or overhasty attempts at
exercise. These can be reduced by cautious setting of targets and
providing information about the cause of possible symptoms after exertion.
Comment
None.
Benefits
We found no systematic reviews or RCTs.
Harms
We found no direct evidence of harmful effects of rest in people
with chronic fatigue syndrome. However, we found observational evidence
suggesting that prolonged inactivity may perpetuate or worsen fatigue
and its associated symptoms in both healthy volunteers22
and in people recovering from viral illness.23
Comment
None.
Benefits
We found no systematic review. Magnesium: We
found one RCT comparing intramuscular injections of magnesium with
placebo in people with chronic fatigue syndrome over a six week
period.24 This trial found important benefits with
magnesium: 12/15 of the treatment group improved compared with 3/17 of
the placebo group. Evening primrose oil: We found two RCTs comparing evening primrose oil with placebo in people with a diagnosis of postviral fatigue syndrome or chronic fatigue syndrome, only one of
which found significant benefit. One RCT compared evening primrose oil
(4 g orally per day) with placebo in 63 people with a diagnosis of
postviral fatigue syndrome.25 At three months, 85% of the
people receiving active treatment had improved compared with 17% on
placebo. However, a further three month trial found no significant
difference between evening primrose oil (4 g orally per day) and
placebo in 50 people with chronic fatigue syndrome (using the
Oxford diagnostic criteria).26
Harms
These trials reported no adverse effects.
Comment
Subsequent studies have failed to find a deficiency of magnesium
in people with chronic fatigue syndrome.27-29 The difference in outcome for the studies of evening primrose oil may be
partly explained by participant selection; the second study used
currently accepted diagnostic criteria.26 Also, whereas the first study used liquid paraffin as a placebo,25 the
second study used sunflower oil, which is better tolerated and less
likely to affect the placebo response adversely.26
Benefits
We found no systematic review. IgG: We found four RCTs
comparing IgG with placebo. In the first, 30 patients were given either
intravenous IgG (1 g/kg) or albumin (placebo) every 30 days.30 After six months no differences were found in
measures of fatigue or physical and social functioning. A similar study
randomised 49 patients to three infusions of either intravenous IgG (2 g/kg) or placebo (a maltose solution).31 Treatment was
given monthly. Ten of the 23 immunoglobulin recipients improved in
terms of a physician rated assessment of symptoms and disability,
compared with three of 26 placebo recipients. The studies differed in
that the second study used twice the dose of IgG, did not require that
participants fulfilled the operational criteria for chronic fatigue
syndrome, and made no assessments of them during the study, waiting
until three months after completion.31 A subsequent
attempt by the same group to replicate the results was
unsuccessful.32 A further trial compared IgG (1 g/kg)
with placebo in 71 adolescents (age 11-18 years).33 Three
infusions were given one month apart. There was a significant
difference between the active treatment and control groups in mean
functional outcome determined by taking the mean of clinician ratings
from four areas of the participants' activities. However, both groups showed significant improvements from baseline, continuing to the six
month post-treatment assessment. Other immunotherapies: We
found one RCT comparing interferon alfa with placebo
(n=30).34 In this study, improvement was found only on
subgroup analysis. Other RCTs have found no significant advantage over
controls from dialysable leucocyte extract (in a factorial design with
cognitive behavioural therapy)35 or
terfenadine.36
Harms
Considerable adverse effects (gastrointestinal complaints,
headaches, arthralgia, and worsening fatigue) were reported with IgG in
up to 82% of trial participants.30 Adverse effects were
also notable with alpha interferon, and two of 13 participants on
active treatment developed neutropenia.34
Comment
None.
Benefits
We found one systematic review, updated in August 1998, which identified 13 RCTs of cognitive behavioural therapy in people
with chronic fatigue syndrome.37 Three trials met the
reviewers' inclusion criteria (all participants fulfilled diagnostic
criteria for chronic fatigue syndrome, use of adequate randomisation,
and use of controls).
35 38 39
The earliest study in 90 people used the Australian diagnostic criteria and evaluated cognitive
behavioural therapy and immunotherapy, using a factorial
design.35 The comparison group received standard medical
care. Cognitive behavioural therapy was given every two weeks for six
sessions lasting 30-60 minutes each. Treatment involved encouraging
participants to exercise at home and feel less helpless. There was no
significant difference in outcomes between cognitive behavioural
therapy and standard care when the Karnofsky scale and symptom report
on a visual analogue scale were used. The second study used the Oxford
diagnostic criteria and compared cognitive behavioural therapy with
normal general practice care in 60 people attending a secondary care
centre.38 The active treatment consisted of a cognitive
behavioural assessment, followed by 16 weekly sessions of behavioural
experiments, problem solving activity, and re-evaluation of thoughts
and beliefs inhibiting return to normal functioning. At 12 months, on
the Karnofsky scale, 73% of those receiving cognitive behavioural
therapy were improved compared with 27% receiving standard care. The
relative benefit increase was 175% (95% confidence interval 54% to
432%), with two people needing to be treated with cognitive
behavioural therapy for one patient to achieve normal functioning (NNT
2; 2 to 5). This study was replicated in the third study in 60 people
attending a different secondary care centre.39 The
cognitive behavioural therapy was given in 13 weekly sessions, and the
control patients received relaxation therapy. Outcome was assessed by
using the medical outcomes survey short form. A good outcome was found
in 63% of those treated with cognitive behavioural therapy compared
with 17% receiving relaxation therapy. The relative benefit increase
was 270% (137% to 531%) with a NNT of 2 (1 to 7). In both the second
and third studies, improvement continued over 6-12 months' follow
up.
38 39
Harms
No harmful effects were reported.
Comment
The disappointing results of the Australian study may have
been because the therapy was less intense and no attempts at cognitive
reappraisal were offered, and because routine care was itself
reasonably effective.35 The conflict between the differing
illness models for the two active treatments being evaluated, cognitive
behavioural therapy and immunotherapy, may also have had an impact on
effectiveness. The Australian diagnostic criteria are no longer widely
used. The other two studies took place in centres with highly skilled
cognitive behavioural therapists.
38 39
The
generalisability of their positive results to settings outside specialist centres remains uncertain. A large Dutch RCT (G Bleijenberg, personal communication) and a British RCT based in primary care (L
Ridsdale et al, personal communication) are due to report shortly.
Benefits
We found no systematic review. We found one RCT using a crossover
design, which compared nicotinamide adenine dinucleotide (NADH) 10 mg a day and placebo over four weeks.40 Of the 33 people
with chronic fatigue syndrome who completed the study, 26 were included
in the analysis. On a symptom rating scale, 8/26 receiving the study
drug attained a 10% improvement, compared with 2/26 receiving placebo.
Harms
Minor adverse effects (loss of appetite, dyspepsia, flatulence)
were reported with the study drug but did not lead to stopping treatment.
Comment
The rationale for this treatment is that NADH facilitates
generation of ATP, which may be depleted in chronic fatigure
syndrome.40 The authors plan to conduct a further
study using greater numbers.
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Acknowledgments |
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We thank Clinical Evidence musclosketal disorders advisers: Troels Mork Hansen, Herlev, Denmark, and John Stothard, Middlesbrough, UK.
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Footnotes |
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Competing interests: None declared.
Clinical Evidence is published by BMJ Publishing Group and American College of Physicians-American Society of Internal Medicine. The first issue is available now, and Clinical Evidence will be updated and expanded every six months. Individual subscription rate, issues 2 and 3, £55/$115; institution rate £132/$211. For more information including how to subscribe, please visit the Clinical Evidence website at www.evidence.org
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