Fink and Schröder challenge the validity of the IoM’s new name and definition of ME/CFS:
Redefining Myalgic Encephalomyelitis/Chronic Fatigue Syndrome
To the Editor: The Institute of Medicine (IOM) proposed a new name (systemic exertion intolerance disease) and diagnostic criteria for myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS).’ The IOM
panel aimed to develop evidence based clinical diagnostic criteria for ME/CFS for use by clinicians, using a consensus-building methodology.”
We agree that more valid diagnostic criteria for ME/CFS are needed and welcome the panel’s effort to improve patient care through better diagnostic tools. However, we do not believe that a new consensus-driven proposal added to the many existing ones will help reach these important aims. The poor acceptance of ME/CFS in the scientific community is due to a lack of convincing evidence that
ME/CFS is a distinct syndrome that can be delimited from other similar syndromes.
Even though the panel’s comprehensive literature review revealed important data indicating the difficult experiences of patients with ME/CFS, the crucial question regarding the nosological status of ME/CFS remains unsolved2 and can be solved only through new scientific studies, not by consensus.
To identify a distinct syndrome, 2 prerequisites need to be proved. First, studies need to show that symptoms cluster (ie, appear together more often than randomly), which can be done using a cluster or factor analysis.1 None of the reported analyses show that the suggested symptoms cluster (postexertion malaise, unrefreshing sleep, cognitive impairment, and orthostatic intolerance).
Second, boundaries or points of rarity between the syndrome and related syndromes need to be identified, which can be achieved with latent class analysis or similar statistical techniques.3 This type of analysis is not reported. Because the suggested symptoms are common in numerous conditions, identifying these boundaries are of paramount importance.
Patients with ME/CFS have multiple symptoms and many fulfill criteria for multiple syndromes.2 4 The new diagnostic proposal does not answer the important question of whether patients who have multisymptomatic ME/CFS have the same illness as patients with few symptoms.
Is ME/CFS a distinct syndrome or part of a spectrum? To answer that question, we need more research that complies with the basic rules on how to establish and validate diagnoses.
Per Fink, PhD. DMSc
Andreas Schroder, MD, PhD
1. Clayton EW. Beyond myalgic encephalomyelitis/chronic fatigue syndrome: an IOM report on redefining an illness JAMA. 2015:313(11) 1101 1102.
2. Wessely S. Nimnuan C. Sharpe M. Functional somatic syndromes: one or mny? Lancet. 1999:354<9182):936-939.
3. Kendell RF. Clinical validity. PsycholMed 1989;19{1) 45-55.
4. Fink P. Schroder A One single diagnosis, bodily distress syndrome,
succeeded to capture 10 diagnostic categories of functional somatic syndromes and somatoform disorders. /Psychosom Res, 2010;68<5) 415
-126.
Ellen Wright Clayton defend the IOM’s process:
In Reply I concur with Drs Fink and Schroder that more research is needed to understand the etiology and refine the diagnosis of systemic exertion intolerance disease. I, however, cannot agree with their conclusion that the IOM Committee’s case definition fails because it was not based on a cluster or factor analysis or latent class analysis or by using similar sta¬tistical techniques.
The Committee examined the existing literature that used these techniques1(pp60-66) and found those studies inadequate for several reasons. The committee also recognized that the framing of salient case definitions frequently relies on a variety of inputs, including expert consensus, input from pa¬tients and stakeholders, and evidence-based review of the lit¬erature that addresses etiology, pathophysiology, and discrimi¬nating clinical characteristics.
The Committee cited 2 examples, the Jones criteria for rheumatic fever and the Diagnostic and Statistical Manual of Mental Disorders, in which case definitions had been made in the absence of clear understanding of etiology.1(p38) In its com¬prehensive literature review, which assessed the quality of available evidence, the Committee focused on identifying symptoms that are found in virtually every patient, with an emphasis on those that have objective findings
on testing in cases of ambiguity. The criteria set forth in the report reflect that analysis. As directed by the statement of task, the criteria and the recommendations also reflect the voices of patients, advocates, and experts inside and outside the Committee who were eloquent in their statements about the seriousness, complexity, and chronicity of this disease, and the misunderstanding and dismissiveness of clinicians and others. I stand by the major contribution of the Committee’s work for these patients.
Ellen Wright Clayton. MD, JD
Read more about the IoM and their report.
Read Dr Lucinda Bateman’s answers to questions about the report
