What is known about severe and very severe chronic fatigue syndrome? A scoping review


Victoria Strassheim, Rebecca Lambson, Katie L. Hackett and Julia L. Newton


CRESTA Fatigue Clinic, Newcastle upon Tyne Hospitals NHS Foundation Trust; Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne, UK



Chronic fatigue syndrome/myalgic encephalomyelitis (CFS/ME) affects 0.4% of the population. It is characterised by disabling fatigue and a combination of self-reported symptoms which include impairments in concentration, short-term memory, sleep disturbances, post-exertional malaise and musculoskeletal pain. There are four categories of severity in the CFS/ME population: mild; moderate; severe; and very severe which are expanded on elsewhere and adopted by the National Institute for Health and Care Excellence [NICE. Chronic fatigue syndrome/myalgic encephelomyelitis diagnosis and management in adults and children; 2007].


Identify research relating to those severely and very severely affected by CFS/ME.


We searched electronic databases for relevant studies using pre-defined search terms: ‘chronic fatigue syndrome’ and ‘sever$’ which covers ‘severe’ and ‘severely’. Included were English language papers published in full that discretely identified severely and very severely affected CFS/ME populations from the broader CFS/ME population.


Over 2000 papers were reviewed and 21 papers met the selection criteria. The capture produced both adult and paediatric populations with a variety of methodologies. Wide differences in illness characterisation, definition and measurement were found. Case studies reported that in extreme presentations very severe CFS/ME individuals may be confined to bed, requiring reduced light and noise exposure.


This review highlights the limited research focusing on the severely affected CFS/ME population. The heterogeneity of the condition contributes to the lack of consensus concerning definitive diagnostic criteria and functional measures to assess disability. Focused research to understand the disease characteristics of the most severely ill will help to advance our understanding of possible phenotypes associated with distinct severity categories.


Strassheim et al, Fatigue: Biomedicine, Health & Behavior, 2017 June 19; 5(3):167–83


We thank ME Research UK for funding the project that allowed this review.

Comment by ME Research UK

As part of an ongoing programme of research at Newcastle University concentrating on severely affected ME/CFS patients, Victoria Strassheim and colleagues have recently published a review of studies conducted in this important but often-neglected subgroup.

We still understand very little about the origin and outcomes of severe ME/CFS, but the prospects for recovery tend to be worse, patients are predisposed to develop secondary medical conditions, and the cumulative impact of severe illness over many years can be profound. It is therefore astonishing that the most basic scientific work has not been carried out in these people.

In her review, Victoria identified 21 papers published over a 24-year period addressing the severely and very severely affected categories of ME/CFS patients, as defined according to Cox’s description (see below). Here are some of her findings:

  • There has been only limited research into those patients severely affected by ME/CFS.
  • Five different sets of diagnostic criteria were used across these studies (Fukuda being the most common), making it difficult to compare results between them, and difficult to know if the same illness if being sampled in each. Furthermore, sometimes these criteria were combined to give much broader criteria.
  • The main cause of disability in these patients was not clear, and several measures were used to assess disability (including the Karnofsky Performance Scale and CFS Disability Scale).
  • The progress of the disease leading to increasing disability was poorly characterised, and this may be because of the range of symptoms and dysfunctions reported. While individuals can move between each of the four categories, the reasons for these transitions were not clear.

The categories of ME/CFS severity

Mildly affected

Severe symptoms (pain, fatigue and unrefreshing sleep), but can manage them in conjunction with work, although with a significant impact on leisure and social time.

Moderately affected

Unable to work, and restricted in all activities of daily living. Often require daily afternoon sleep.

Severely affected

Can only carry out minimal daily tasks (personal hygiene feeding, etc.). Severe cognitive difficulties, wheelchair dependent, rarely leave home, and have severe prolonged after effects from effort.

Very severely affected

Bedbound for most of the time, and unable to carry out daily tasks independently. Often intolerant to noise and sensitive to light.

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