Evaluating case diagnostic criteria for myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS): toward an empirical case definition

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

Automated summary

This study evaluated the validity of different case definitions for ME/CFS and identified several symptom domains. Revision of the existing criteria is recommended.