Fatigue

Causes of fatigue

The physiological and psychological mechanisms underlying subjective fatigue are poorly understood. Fatigue may rather be usefully regarded as a final common pathway for a variety of causal factors. These can be split into predisposing, precipitating, and perpetuating factors.

Predisposing factorsinclude being female and a history of either fatigue or depression.

Precipitating factorsinclude acute physical stresses such as infection with Epstein-Barr virus, psychological stresses such as bereavement, and social stresses such as work problems.

Perpetuating factorsinclude physical inactivity, emotional disorders, ongoing psychological or social stresses, and abnormalities of sleep. These factors should be sought as part of the clinical assessment.

Other physiological factors such as immunological abnormalities and slightly low cortisol concentration are of research interest but not clinical value.

Assessment and formulation

History—The nature of the fatigue is an important clue to diagnosis, and it is therefore important to clarify patients' complaints. Fatigue described as loss of interest and enjoyment (anhedonia) points to depression. Prominent sleepiness suggests a sleep disorder. The history should also cover

• Systematic inquiry for diseases often associated with fatigue

• Symptoms of depression anxiety and sleep disorder

• Patients' own understanding of their illness and how they cope with it

• Current social stresses.

Examination—Both a physical and mental state examination must be performed in every case, to seek medical and psychiatric diagnoses associated with fatigue.

Routine investigations—If there are no specific indications for special investigations, a standard set of screening tests is adequate.

Special investigations—Immunological and virological tests are generally unhelpful as routine investigations. Sleep studies can be useful in excluding other diagnoses, especially obstructive sleep apnoea and narcolepsy.

Psychological assessment—It is important to inquire fully about patients' understanding of their illness (questions may include “What do you think is wrong with you?” and “What do you think the cause is?”). Patients may be worried that the fatigue is a symptom of a severe, as yet undiagnosed, disease or that activity will cause a long term worsening of their condition.

Formulation—A formulation that distinguishes predisposing, precipitating, and multiple perpetuating factors is valuable in providing an explanation to patients and for targeting intervention.

General management

Persistent fatigue requires active management, preferably before it has become chronic. When a specific disease cause of fatigue can be identified this should be treated. If no disease diagnosis can be made, or if medical treatment of disease fails to relieve the fatigue, a broader biopsychosocial management strategy is required. A discussion with the patient about fatigue and its treatment can be supplemented with written material (see below).

Patients should be told that they are suffering from a common and treatable condition that the doctor takes seriously and for which behavioural treatment can be helpful. While patients may be concerned about possible disease and the need for medical investigation and treatment, it can be explained that no disease has been found, and hence there is no disease based treatment, but that with help there is a great deal that the patients can do themselves.

Identifying unhelpful beliefs—Potentially unhelpful beliefs should be discussed. If a patient has a simple aetiological model (such as “It is all due to a virus”) an alternative approach based on a biopsychosocial formulation can be outlined. This has the advantage of highlighting potential perpetuating factors, as these may be regarded as obstacles to recovery. Doctor and patient can then work together to overcome these. It is rarely productive to argue over the best name for the illness; instead, the emphasis should be on agreeing a positive and open minded approach to rehabilitation.

Patients should be encouraged to gradually increase their activity. (“Mrs Bradbury's establishment for the recovery of ladies nervously affected,” from On insanity by William B Neville London 1836)

Managing activity and avoidance—Gradual increases in activity can be advised unless there is a clear contraindication. It is critical, however, to distinguish between carefully graded increases carried out in collaboration with patients and “forced” exercise. It is also important to explain that erratic variation between overactivity on “good” days and subsequent collapse does not help long term recovery and that “stabilising” activity is a prerequisite to graded increases.

Efficacy of cognitive behaviour therapy for treating chronic fatigue syndrome

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Depression and anxiety—If there is evidence of depression a trial of an antidepressant drug is worth while. Patients with fatigue are often sensitive to the side effects of antidepressants. However, if they are given adequate information about what to expect when treatment begins, with small doses, most patients can tolerate them. Randomised trials have shown psychological therapies such as cognitive behaviour therapy to be equally effective for mild to moderate depression.

Managing occupational and social stresses—Patients who remain in work may be overstressed by it. Those who have left work may be inactive and demoralised and may not wish to return to the same job. These situations require a problem solving approach to consider how to manage work demands, achieve a return to work, or to plan an alternative career.

Referral for specialist management

Most patients with fatigue are managed in primary care, but certain groups may require referral to specialist care:

• Children with chronic fatigue

• Patients in whom the general practitioner suspects occult disease

• Patients with severe psychiatric illness

• Patients requiring specialist management of sleep disorders

• Patients unresponsive to management in primary care.

Referral may be to a physician or psychiatrist as is deemed most appropriate. Psychologists may be able to offer cognitive behaviour therapy. Where available, joint medical and psychiatric clinics are ideally suited to the assessment of chronic fatigue and related problems. It is essential there is close liaison between primary and specialist care to ensure a clear, consistent, and encouraging approach by all concerned.

Conclusion

Fatigue is a ubiquitous symptom that is important to patients and has a major impact on their quality of life. It remains poorly understood and has hitherto probably been not been given adequate attention by doctors. Early and active management of fatigue in primary care may prevent progression to chronicity. Patients who have developed a chronic fatigue syndrome can benefit from specific treatments. Paying more attention to the symptom of fatigue may help to avoid the distress and poor outcome that is associated with patients feeling that their problems are neither accepted nor understood. It may also reduce the numbers who turn to a variety of unproved, and even harmful, alternative approaches.