The importance of a research case definition

Dolphin

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Fatigue: Biomedicine, Health & Behavior


Commentaries

The importance of a research case definition

Leonard A. Jason, Pamela A. Fox & Kristen D. Gleason
Pages 1-7 | Received 01 Aug 2017, Accepted 04 Oct 2017, Published
online: 12 Oct 2017


http://dx.doi.org/10.1080/21641846.2018.1389336





ABSTRACT

All scientific activities with diseases rely on the selection of reliable and valid case definitions in order to accurately estimate prevalence rates, to identify biological markers, and to understand the outcomes of treatment trials.

The failure to develop a consensus on which research case definition to use for defining Myalgic Encephalomyelitis (ME) and chronic fatigue syndrome (CFS) has had negative consequences for the scientific and patient community.

If case definition criteria inappropriately select patients with symptoms due to primary affective disorders, other fatiguing medical conditions, burnout, or over-committed lifestyle issues, the scientific consequences are serious.

For example, a case definition that is too broad would include individuals with other illnesses and conditions, complicating the tasks of estimating prevalence rates or identifying effective treatment programs.

A consensus on a research case definition and its operationalization and assessment would enable investigators to select more homogenous samples that could expedite the identification of valid biological markers, and consequently reduce misperceptions regarding the role of psychogenic versus biomedical factors.

Our editorial reviews the implications of previous research and clinical case definitions in CFS and ME domains.

KEYWORDS: Case definitions, myalgic encephalomyelitis, chronic fatigue
syndrome, diagnositic criteria
 

Pyrrhus

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Excerpt:

Jason et al 2017 said:
If case definitions are too broad, individuals with other illnesses or conditions may be inappropriately brought into such studies. As with the PACE [1] trial, this complicates the interpretation of outcomes [2], but this also has serious consequences for other scientific activities such as estimating prevalence rates and identifying biological markers.
[...]
There are certainly many case definitions for describing and diagnosing ME and CFS. However, few are suitable for identifying a homogeneous research population. For example, the Oxford case definition [3] only requires six months of chronic fatigue for a diagnosis of CFS, a standard that is too broad for use as a research case definition. The Fukuda et al. [4] criteria also lacks specificity in that it does not require post-exertional malaise, which has been shown to be a key distinguishing symptom of the illness [5].

It is not just the US that is experiencing difficulties in developing a consensus on a research case definition, as the ME/CFS Epidemiology and Genomics Alliance (MEGA) [6] study in the UK is proposing to use the NICE criteria, which only requires fatigue plus one other symptom. Using any such imprecise case definition can have substantial effects on a scientific field.
 

Pyrrhus

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And here are some research papers that looks at brain differences between ME-ICC and CFS-Fukuda patient cohorts:

Diffusion tensor imaging reveals neuronal microstructural changes in ME/CFS (Thapaliya et al., 2021)
https://forums.phoenixrising.me/thr...agnostic-criteria-thapaliya-et-al-2021.85111/

Volumetric differences in hippocampal subfields and associations with clinical measures in ME/CFS (Thapaliya et al., 2022)
https://forums.phoenixrising.me/thr...easures-in-me-cfs-thapaliya-et-al-2022.87423/