Chronic fatigue syndrome: identifying zebras amongst the horses

Abstract

There are currently no investigative tools or physical signs that can confirm or refute the presence of chronic fatigue syndrome (CFS). As a result, clinicians must decide how long to keep looking for alternative explanations for fatigue before settling on a diagnosis of CFS. Too little investigation risks serious or easily treatable causes of fatigue being overlooked, whilst too many increases the risk of iatrogenic harm and reduces the opportunity for early focused treatment. A paper by Jones et al published this month in BMC Medicine may help clinicians in deciding how to undertake such investigations. Their results suggest that if clinicians look for common psychiatric and medical conditions in those complaining of prolonged fatigue, the rate of detection will be higher than previously estimated. The most common co-morbid condition identified was depression, suggesting a simple mental state examination remains the most productive single investigation in any new person presenting with unexplained fatigue. Currently, most diagnostic criteria advice CFS should not be diagnosed when an active medical or psychiatric condition which may explain the fatigue is identified. We discuss a number of recent prospective studies that have provided valuable insights into the aetiology of chronic fatigue and describe a model for understanding chronic fatigue which may be equally relevant regardless of whether or not an apparent medical cause for fatigue can be identified.See the associated research paper by Jones et al: http://www.biomedcentral.com/1741-7015/7/57 CommentaryMedical students are often told that the sound of approaching hooves is more likely to herald the arrival of horses than zebras. The metaphor reinforces the idea that in medicine common things happen commonly and that clinicians should avoid spending too much time chasing rare or unlikely diagnoses. Fatigue is a very common clinical problem with many possible causes [1,2]. Some causes of fatigue are common 'horses' such as anaemia, viral infections, sleep deprivation, diabetes and depression. However, potential 'zebras' such as malignancy or auto-immune disorders may also present with fatigue. Even with extensive investigations, the underlying aetiology of an individual's fatigue in many cases remains unknown. Over recent decades there has been increasing recognition of a group of individuals with severe, persistent, and unexplained fatigue [3]. Such persistent fatigue has, at times, been seen as an illness of modern life, although there is good evidence to show that chronic fatigue has been a common problem since at least the 19th century, but under different diagnostic labels, such as neurasthenia [4,5]. Some, but by no means all, of these individuals fulfil the current criteria for chronic fatigue syndrome (CFS), which requires that persisting or relapsing fatigue be present for at least 6 months, is not relieved by rest, is not explained by medical or psychiatric condi-

Chronic fatigue syndrome – an update

“…Over the years, the biopsychosocial model integrating many of the proposed hypotheses (psychological predisposing and persisting factors, and psychological or physical precipitating factors) has been gaining popularity. 57 As long as the etiopathogenesis of CFS is not completely understood, therapy should be based on these findings. The primary goal of CBT is to obtain control of the symptoms.…”

“…58 The main goal of pacing therapy, another aspect of many of the current exercise programs, is to achieve adaptation to the perceived illness by planning and pacing the patients' activities according to their available energy in gaining popularity over the biomedical model where the focus is on one physical cause (Figure 1). 57 Certain individuals are more prone to develop CFS, e.g. those with psychiatric disorders, perfectionism, psychosocial problems, childhood stressors, and an overactive lifestyle.…”

“…These two therapies interfere with the maintaining factors of the biopsychosocial model. 57 The primary goal of CBT is to obtain control of the symptoms. 58 Dysfunctional beliefs and thoughts are dealt with and harmful or unhelpful behavior is changed through therapeutic sessions.…”

Perfectionism and Maladaptive Coping Styles in Patients with Chronic Fatigue Syndrome, Irritable Bowel Syndrome and Fibromyalgia/Arthritis and in Healthy Controls

“…Biopsychosocial models of chronic fatigue syndrome (CFS) posit that personality and stress have predisposing and perpetuating roles in the persistent and unexplained fatigue that characterizes this functional somatic syndrome [1]. Studies indicate that many CFS patients are characterized by an achievement-oriented and perfectionistic personality, and that such tendencies coupled with self-criticism drive these individuals to work beyond the point of exhaustion in a way that may initiate or perpetuate chronic fatigue [2].…”

How Should Functional Somatic Syndromes Be Diagnosed?

“…A number of authors have criticised this definition, noting that the idea that symptoms can be divided into those totally explained by physical conditions and those that are 'medically unexplained' is almost certainly false, not reflective of good clinical practice and encourages a dualistic divide between medicine and psychiatry [7]. We and others have previously discussed the dangers of such dualistic approaches with other disorders, such as chronic fatigue [8]. We now have strong evidence for the role of psychological factors as risk and maintaining factors in many cases of 'medically unexplained' fatigue [9][10][11][12].…”