Abstract
Background: The diagnosis of myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) is complex and largely based on self-reported symptom profiles. The field lacks consensus for a singular case definition and heterogeneous samples make comparability across studies difficult. Purpose: The present study sought to validate a comprehensive self-report measure of ME/CFS symptomatology to aid in clinical and research assessment. Methods: Exploratory factor analysis (EFA) was used to establish the underlying factor structure of the DePaul Symptom Questionnaire (DSQ) using a well-characterized sample of individuals (92.6% met the Fukuda et al. criteria and/or the Clinical Canadian Criteria) and this structure was then tested on a less stringently recruited sample of individuals utilizing a confirmatory factor analysis (CFA). Convergent and discriminant validity of the DSQ were also examined utilizing alternative measures of symptomatology and functioning. Results: A three-factor solution was found using EFA (Neuroendocrine, Autonomic, and Immune Symptoms; Neurological/Cognitive Dysfunction; Post-Exertional Malaise) and the fit of this factor structure was adequate for the second sample. The DSQ was found to have good convergent and discriminant validity. Conclusions: The DSQ is a valid tool for assessing ME/CFS symptoms. There may be two core ME/CFS symptom clusters: post-exertional malaise and cognitive dysfunction.
Acknowledgments
The authors appreciate the CFIDS Association of America, which approved the use of de-identified Solve CFS BioBank registry data in this analysis.
Funding
Funding was provided by National Institute of Allergy and Infectious Diseases [Grant numbers AI 49720 and AI 055735].
Additional information
Notes on contributors
Abigail A. Brown
Abigail A. Brown, M.A., is an advanced graduate student in Clinical-Community Psychology at DePaul University.
Leonard A. Jason
Leonard A. Jason, Ph.D., is a Professor of Psychology and Director of the Center for Community Research at DePaul University.