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Research Articles

Examining case definition criteria for chronic fatigue syndrome and myalgic encephalomyelitis

, , , , , & show all
Pages 40-56
Received 29 Jun 2013
Accepted 26 Oct 2013
Published online: 11 Dec 2013
 

Background: Considerable controversy has transpired regarding the core features of myalgic encephalomyelitis (ME) and chronic fatigue syndrome (CFS). Current case definitions differ in the number and types of symptoms required. This ambiguity impedes the search for biological markers and effective treatments. Purpose: This study sought to empirically operationalize symptom criteria and identify which symptoms best characterize the illness. Methods: Patients (n = 236) and controls (n = 86) completed the DePaul Symptom Questionnaire, rating the frequency and severity of 54 symptoms. Responses were compared to determine the threshold of frequency/severity ratings that best distinguished patients from controls. A Classification and Regression Tree (CART) algorithm was used to identify the combination of symptoms that most accurately classified patients and controls. Results: A third of controls met the symptom criteria of a common CFS case definition when just symptom presence was required; however, when frequency/severity requirements were raised, only 5% met the criteria. Employing these higher frequency/severity requirements, the CART algorithm identified three symptoms that accurately classified 95.4% of participants as patient or control: fatigue/extreme tiredness, inability to focus on multiple things simultaneously, and experiencing a dead/heavy feeling after starting to exercise. Conclusions: Minimum frequency/severity thresholds should be specified in symptom criteria to reduce the likelihood of misclassification. Future research should continue to seek empirical support of the core symptoms of ME and CFS to further progress the search for biological markers and treatments.

Acknowledgments

The authors appreciate the CFIDS Association of America, which approved the use of de-identified SolveCFS BioBank registry data in this analysis.

Funding

Funding was provided by NIAID [Grant numbers AI 49720 and AI 055735].

Additional information

Notes on contributors

Leonard A. Jason

Leonard A. Jason is a Professor of Psychology and Director of the Center for Community Research at DePaul University.

Madison Sunnquist

Madison Sunnquist is a Research Assistant at the Center for Community Research at DePaul University.

Abigail Brown

Abigail Brown is an advanced graduate student in the clinical-community psychology program at DePaul University.

Meredyth Evans

Meredyth Evans is an advanced graduate student in the clinical-community program at DePaul University.

Suzanne D. Vernon

Suzanne D. Vernon is the Scientific Director of the CFIDS Association of America.

Jacob D. Furst

Jacob D. Furst is an Associate Professor in the College of Computing and Digital Media (CDM) at DePaul University.

Valerie Simonis

Valerie Simonis is a graduate student in the College of Computing and Digital Media (CDM) at DePaul University.

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