Evaluating case diagnostic criteria for myalgic encephalomyelitis/ chronic fatigue syndrome (ME/CFS): toward an empirical case definition, by Karl E Conroy, Mohammed F Islam, Leonard A Jason in Disability and Rehabilitation, Mar 2, p 1-8 2022 [doi.org/10.1080/09638288.2022.2043462]


Implications for rehabilitation

  • ME/CFS is a chronic illness with no consensus regarding case diagnostic criteria, which creates difficulty for patients seeking assistance and disability benefits.
  • The current study compared three commonly used case definitions for ME/CFS by factor analyzing symptomological data from an international sample of patients.
  • Our results suggest three primary and four secondary symptom domains which differed from all three case definitions.
  • These findings could help reduce barriers to care for those disabled with ME/CFS by guiding the development of an empirically-based case definition.



Myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) is an illness characterized by a variety of symptoms including post-exertional malaise, unrefreshing sleep, and cognitive impairment. A variety of case definitions (e.g., the Canadian Consensus Criteria (CCC), the Myalgic Encephalomyelitis International Consensus Criteria (ME-ICC), and the Institute of Medicine (IOM) criteria) have been used to diagnose patients. However, these case definitions are consensus-based rather than empirical.

Materials and methods

The aim of the current study was to evaluate the validity of the aforementioned case definitions by factor analyzing a large, international sample (N = 2308) of ME/CFS symptom data. We performed primary and secondary exploratory factor analyses on the DePaul Symptom Questionnaire‘s 54-item symptom inventory. These results were compared to the CCC, the ME-ICC, and the IOM criteria.


We identified seven symptom domains, including post-exertional malaise, cognitive dysfunction, and sleep dysfunction. Contrary to many existing case criteria, our analyses did not identify pain as an independent factor.


Although our results implicate a factor solution that best supports the CCC, revisions to the criteria are recommended.

Full paper behind paywall

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