Review of case definitions for myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS): Eun-Jin Lim July 2020

[Sly Saint]

Abstract
Background

Myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) is a debilitating disease with unknown causes. From the perspectives on the etiology and pathophysiology, ME/CFS has been labeled differently, which influenced changes in case definitions and terminologies. This review sought to feature aspects of the history, developments, and differential symptoms in the case definitions.

Methods
A search was conducted through PubMed published to February 2020 using the following search keywords: case definition AND chronic fatigue syndrome [MeSH Terms]. All reference lists of the included studies were checked. Of the included studies, the number of citations and the visibility in the literatures of the definitions were considered for comparisons of the criteria.

Results
Since the first 'ME' case definition was developed in 1986, 25 case definitions/diagnostic criteria were created based on three conceptual factors (etiology, pathophysiology, and exclusionary disorders). These factors can be categorized into four categories (ME, ME/CFS, CFS, and SEID) and broadly characterized according to primary disorder (ME-viral, CFS-unknown, ME/CFS-inflammatory, SEID-multisystemic), compulsory symptoms (ME and ME/CFS-neuroinflammatory, CFS and SEID-fatigue and/or malaise), and required conditions (ME-infective agent, ME/CFS, CFS, SEID-symptoms associated with fatigue, e.g., duration of illness). ME and ME/CFS widely cover all symptom categories, while CFS mainly covers neurologic and neurocognitive symptoms. Fatigue, cognitive impairment, PEM, sleep disorder, and orthostatic intolerance were the overlapping symptoms of the 4 categories, which were included as SEID criteria.

Conclusions
This study comprehensively described the journey of the development of case definitions and compared the symptom criteria. This review provides broader insights and explanations to understand the complexity of ME/CFS for clinicians and researchers.

https://translational-medicine.biomedcentral.com/articles/10.1186/s12967-020-02455-0

 

[Obermann]

It is an interesting paper, but I think they miss an important point. Epidemic ME was a contagious disease with unknown aetiology, although circumstantial evidence suggests it was caused by a viral infection, possibly an enterovirus. The illness had an alarming tendency to trigger the postviral syndrome that we now call ME/CFS. Note that it was listed in the section “Inflammatory diseases of central nervous system” in ICD-8 (1969).

In the 1980s, focus shifted from the acute phase in the epidemics to the postviral condition. It was acknowledged that a syndrome with similar clinical presentation could be triggered by other infectious agents. The name postviral fatigue syndrome was introduced in ICD-10 (1994), and the illness moved to the section “Other disorders of the nervous system”.

I think it is very difficult to follow the history of ME/CFS, if you don’t make a distinction between the acute phase in epidemic ME on the one hand and the postviral sequel to epidemic ME and other viral agents—that we now call ME/CFS—on the other hand.

 

[chrisb]

Yes. The difficulty arises when some people conclude that it is therefore unnecessary to counter the suggestion that the "post-viral" effects of epidemic ME were hysteria.

The lesson of the RFH was that there was an unidentified and possibly unknown pathogen which, even by McEvedy's data, led to an ongoing illness in approximately 10% of those infected - seven out of seventy odd, rather than the headline figure of one remaining ill for up to a year.

 

[ME/CFS Skeptic]

Looks like a reasonable overview