Chronic fatigue syndrome

Definition/diagnostic criteria Chronic fatigue syndrome (CFS), also known as myalgic encephalomyelitis (ME), is a complex and debilitating condition characterised by severe fatigue, cognitive impairments, and other symptoms that significantly impact a person’s daily life.

There is no diagnostic test for CFS. The diagnosis should be considered if key symptoms have been present for at least 6 weeks and cannot be explained by another illness.

Epidemiology CFS is a relatively common condition in the UK, with an estimated prevalence of 0.2-0.4% in the general population. It affects people of all ages, although it is most commonly diagnosed in individuals aged 20 to 50 years. Women are more frequently affected than men, with a female-to-male ratio of approximately 2:1.

Diagnosis
Clinical features: CFS is a fluctuating medical condition that affects everyone differently

Symptoms, which must have been present for at least 6 weeks in the absence of another underlying illness:

• Severe fatigue: The hallmark symptom of CFS is severe, debilitating fatigue that is not relieved by rest.
• Post-exertional malaise: Patients often experience a worsening of symptoms after physical or mental exertion.
• Unrefreshing sleep: Despite sleeping for an adequate duration, CFS patients wake up feeling unrefreshed.
• Cognitive impairment: Cognitive difficulties, commonly referred to as ‘brain fog’, can include memory problems and difficulty concentrating.

Other common CFS symptoms include:

• Musculoskeletal pain, headaches, sore throat, flu like symptoms, gastrointestinal symptoms, neurological symptoms, orthostatic dysfunction and tender lymph nodes.

GPs should refer patients to a specialist CFS service if the diagnostic criteria are met and symptoms have persisted for 3 months and are not explained by another condition.

Investigations The primary purpose of investigations is to exclude other possible causes of fatigue and confirm the diagnosis of CFS. Investigations should include:

• Full blood count and serum ferritin.
• ESR or CRP.
• Liver function tests.
• Renal function tests.
• Thyroid function.
• Coeliac screen.
• CK, bone biochemistry and myeloma screen.

Use clinical judgement to decide on additional investigations to exclude other diagnoses, for example:

• Vitamin D, vitamin B12 and folate levels.
• Serological tests if there is a history of infection.
• Sleep studies if symptoms of obstructive sleep apnoea.
• 9am cortisol for adrenal insufficiency).

Typically, these investigations will show no significant abnormalities in CFS patients, further supporting the diagnosis.

Treatment The management of CFS is multifaceted and aims to alleviate symptoms and improve the patient’s quality of life. Treatment depends on a patient’s symptom profile and severity of illness.

• NICE guidelines recommend the development of a personalised care and support plan by a CFS specialist service. This may include a combination of symptom management and cognitive-behavioural therapy (CBT).
• Symptom management may include pain relief, sleep management, treatment of orthostatic instability, treatment of depression and anxiety and dietary advice.

Prognosis CFS is a chronic condition with a variable prognosis. Some individuals may recover fully, while others may experience ongoing symptoms for years. Early intervention, appropriate management, and support from healthcare providers can significantly improve the prognosis and the patient’s overall wellbeing.