Tag: clinical definition

Case definitions and diagnostic criteria for Myalgic Encephalomyelitis and Chronic fatigue Syndrome: from clinical-consensus to evidence-based case definitions

Abstract:

The symptom spectrum of Myalgic Encephalomyelitis (ME) was first detailed in 1959 and later operationalised into a diagnostic protocol (Melvin Ramsey). In 1988 the Holmes case definition coined the term chronic fatigue syndrome (CFS). Fukuda’s Centers for Disease Control and Prevention criteria are very heterogeneous and comprise patients with milder symptoms than the Holmes case definition. The CDC Empirical Criteria for CFS lack sensitivity and/or specificity. Other CFS definitions, e.g. the Oxford criteria, delineate people with idiopathic fatigue. Some authors make the clinical CFS diagnosis when slightly increased self-rated fatigue scores are present. In 2011, Carruthers’ International Consensus Criteria attempted to restore the focus on selecting people who suffer from ME.

Cognitive bias in criteria construction, patient selection, data collection and interpretation has led to the current state of epistemological chaos with ME, CFS, CFS/ME and ME/CFS, and CF being used interchangeably. Moreover, none of the above mentioned classifications meet statistically based criteria for validation. Diagnostic criteria should be based on statistical methods rather than consensus declarations. Ongoing discussions about which case definition to employ miss the point that the criteria did not pass appropriate external validation.

In 2012, Maes et al. performed pattern recognition methods and concluded that CFS patients (according to Fukuda’s criteria) should be divided into those with CFS or ME, on the basis that people with ME display a worsening of their illness following increases in physical or cognitive activity. Both ME and CFS are complex disorders that share neuro-immune disturbances, which are more severe in ME than in CFS. This paper expands on that strategy and details a range of objective tests, which confirm that a person with ME or CFS has a neuro-immune disease.

By means of pattern recognition methods future research should refine the Maes’ case definitions for ME and CFS by including well-scaled symptoms, staging characteristics and neuro-immune biomarkers, including immune-inflammatory assays, bioenergetic markers and brain imaging.

 

Source: Morris G, Maes M. Case definitions and diagnostic criteria for Myalgic Encephalomyelitis and Chronic fatigue Syndrome: from clinical-consensus to evidence-based case definitions. Neuro Endocrinol Lett. 2013;34(3):185-99. https://www.ncbi.nlm.nih.gov/pubmed/23685416

 

Comment:

Ellen M Goudsmit

2014 Mar 01 2:10 p.m.
Dr. Melvin Ramsay began writing about the illness now known as ME after the outbreak in north London in 1955. I looked in his book (1988) for a paper written by him in 1959 and found none. The best known article from 1959 was written by the late Dr. Acheson, who gave ME its name in a leader in the Lancet (1956). Dr Ramsay offered a diagnostic protocol but not until the 1980s.

I agree with Morris and Maes that the core symptom of ME is an exacerbation of symptoms following minimal exertion (supported by Paul et al who referred to CFS but actually selected patients with ME, pers. comm.). It should also be noted that none of the existing criteria for ME and CFS have been found to have the required specificity and sensitivity. And that includes the 2011 version.
The abstract indicates a lack of attention to detail. This undermines the understanding of the issues and shows a lack of respect, not only for the researchers but also for the patients, 99% of whom would know how to spell the name of arguably one of the most knowledgeable experts in this field. This failure to check for accuracy is a major cause for confusion in the literature on ME and CFS. And what happened to peer review? Any peer would have noticed the problem with the first sentence.
People really interested in ME and CFS may like to purchase an excellent publication by Shepherd and Chaudhuri summarising the knowledge to date. It’s available from the ME Association in the UK. An authoritative and accurate review (2013).
Leading article. A new clinical entity? Lancet, 1956, 1, 789-790.
Paul, L et al. Demonstration of delayed recovery from fatiguing exercise in chronic fatigue syndrome. European Journal of Neurology, 1999, 6, 63-69.
Ramsay, AM. Myalgic encephalomyelitis and postviral fatigue states. Second Ed. Gower Medical Publ. 1988. now available from the MEA Association, UK.

 

Can the chronic fatigue syndrome be defined by distinct clinical features?

Abstract:

To determine whether patients diagnosed as having chronic fatigue syndrome (CFS) constitute a clinically homogeneous class, multivariate statistical analyses were used to derive symptom patterns and potential patient subclasses in 565 patients. The notion that patients currently diagnosed as having CFS constitute a single homogeneous class was rejected.

An alternative set of clinical subgroups was derived. The validity of these subgroups was assessed by sociodemographic, psychiatric, immunological and illness behaviour variables. A two-class statistical solution was considered most coherent, with patients from the smaller class (27% of the sample) having clinical characteristics suggestive of somatoform disorders. The larger class (73% of sample) presented a more limited combination of fatigue and neuropsychological symptoms, and only moderate disability but remained heterogeneous clinically. The two patient groups differed with regard to duration of illness, spontaneous recovery, severity of current psychological morbidity, utilization of medical services and CD8 T cell subset counts. The distribution of symptoms among patients was not unimodal, supporting the notion that differences between the proposed subclasses were not due simply to differences in symptom severity.

This study demonstrated clinical heterogeneity among patients currently diagnosed as CFS, suggesting aetiological heterogeneity. In the absence of discriminative clinical features, current consensus criteria do not necessarily reduce the heterogeneity of patients recruited to CFS research studies.

 

Source: Hickie I, Lloyd A, Hadzi-Pavlovic D, Parker G, Bird K, Wakefield D. Can the chronic fatigue syndrome be defined by distinct clinical features? Psychol Med. 1995 Sep;25(5):925-35. http://www.ncbi.nlm.nih.gov/pubmed/8588011

 

Chronic Fatigue Syndrome

Abstract:

Despite its new name, chronic fatigue syndrome is not a new disease. This chapter reviews current definitions, emphasizing that chronic fatigue syndrome is a diagnosis of exclusion. The author also discusses viral infections that are associated with CFS, including Epstein-Barr virus, cytomegalovirus, herpesvirus type 6, enteroviruses, and retroviruses.

 

Source: Glover DM. Chronic Fatigue Syndrome. Adolesc Med. 1995 Feb;6(1):101-114. http://www.ncbi.nlm.nih.gov/pubmed/10358305

 

Chronic fatigue syndrome. …and study them separately

Comment on: Chronic fatigue syndrome: prevalence and outcome. [BMJ. 1994]

 

Editor,-The struggle over myalgic encephalomyelitis and the chronic fatigue syndrome is not, as S M Lawrie and A J Pelosi suggest, whether they are physical or mental illnesses. Both sides in this debate accept that most illnesses combine organic and psychological factors. The struggle is about methodology and definition and, in particular, how different methodologies and definitions inevitably lead to different findings on the degree to which depression is a perpetuating agent in these conditions.

One side favours studying the chronic fatigue syndrome as a single entity, arguing that there is insufficient knowledge at present to differentiate between different chronic fatigue syndromes. This side prefers Sharpe et al’s broad definition of the syndrome, which includes depressive illness, anxiety disorders, and the hyperventilation syndrome.2 Unsurprisingly, studies that use these criteria find higher levels of depression ) or “psychosocial disorders”-yet another woolly term).

The other side argues that there is sufficient knowledge to distinguish specific chronic fatigue syndromes, particularly the much studied myalgic encephalomyelitis, and that it must be better science in these cases to study such syndromes in their own right. Furthermore, it argues that the study groups used in research based on broadbrush criteria will have been so aetiologically heterogeneous as to invalidate the findings. This side, which includes the national patient organisations, equates myalgic encephalomyelitis with Holmes et als tighter definition of the chronic fatigue syndrome, which focuses more on organic symptoms and, again unsurprisingly, finds lower levels of depression similar to those found in patients with cancer and multiple sclerosis-that is, the levels that might be predicted in any chronic illness.3

You can read the rest of this comment here: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2540172/pdf/bmj00440-0054a.pdf

 

Source: Anderson N. Chronic fatigue syndrome. …and study them separately. BMJ. 1994 May 14;308(6939):1298. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2540172/

 

Epidemic neuromyasthenia and chronic fatigue syndrome: epidemiological importance of a cluster definition

Abstract:

Outbreaks of illness variously identified by a number of terms, including epidemic neuromyasthenia, myalgic encephalomyelitis, Iceland disease, and atypical poliomyelitis, have been reported from many countries during the past 45 years.

Since the first well-described outbreak occurring in 1934, > 60 outbreaks have been reported, but few of these have been described in considerable detail. These outbreaks are usually cited in historical reports of chronic fatigue syndrome (CFS) since each of these outbreaks appears to contain a number of cases meeting the current case definition of CFS.

There has been inadequate attention given to the fact that epidemic neuromyasthenia and related clusters characterized by various complaints, including fatigue, do not have an accepted epidemiological or clinical definition, and only rarely have descriptions of these clusters included a specific case definition. When such case definitions have been applied, the occurrence of cases meeting the current case definition for CFS appears to be both variable and infrequent.

This report utilizes examples of several well-documented outbreaks to emphasize specific aspects that should be considered in the investigation of future clusters.

 

Source: Levine PH. Epidemic neuromyasthenia and chronic fatigue syndrome: epidemiological importance of a cluster definition. Clin Infect Dis. 1994 Jan;18 Suppl 1:S16-20. http://www.ncbi.nlm.nih.gov/pubmed/8148446