Toward an Empirical Case Definition of CFS

Abstract

The current case definition of chronic fatigue syndrome (CFS) was developed by consensus rather than empirical methods. From a practice point of view, if the case definition is not empirically-based, it is possible that some individuals with this illness might not be diagnosed, and others who do not have the disorder might be diagnosed. In the present study, 114 individuals with CFS were provided a theoretically driven questionnaire that featured neuropsychiatric, vascular, inflammatory, muscle/joint, infectious, and other symptoms. When symptoms using this classification were factor analyzed, a more interpretable factor structure was identified than when using symptoms from traditional case definition criteria. Factor scores from the new classification system were cluster analyzed, and four types of patient groups were identified. The field of CFS studies needs to be grounded in empirical methods for determining a case definition versus more consensus-based efforts. Such efforts will ultimately help social service providers better diagnose and provide services to those with this chronic illness.

Key Words:

• CFS
• factor analysis
• cluster analysis
• nosology