Characteristics of Fatigued Persons Associated with Features of Chronic Fatigue Syndrome

Background: Characteristics of persons with chronic fatigue syndrome (CFS) have previously been studied by comparing subjects with CFS to subjects with other conditions or no symptoms of fatigue- In the present study of subjects with idiopalhic chronic fatigue we examined the association between the number and severity of the features of CFS with other characteristics of the subjects.Methods: Data were obtained from a registry of persons over the age of 17 with fatigue for at least six months. All subjects in the registry completed an extensive questionnaire that provided information about fatigue, demographic characteristics, medical conditions, life style, sleeping habits, and psychological characteristics. The characteristics of the subjects were tested for an association with the number of CFS symptoms and the severity of individual CFS symptoms that are considered to be of fundamental importance and may identify more homogeneous subjects with chronic fatigue.Results: The number of CFS symptoms had a bell shaped distribution. This number was strongly associated with the severity of fatigue, the response of fatigue to mental and physical activity, and the following subject characteristics: a greater frequency of sinus and respiratory infections, a higher frequency of migraine headaches, a greater number of somatoform symptoms that were not included as criteria for CFS, and not drinking alcohol. These same subject characteristics were generally associated with at least one of the individual CFS symptoms but more weakly. Psychological complaints only had a statistically significant positive association with one feature of CFS, neurocognitive complaints.Conclusions: Persons with fatigue can be usefully characterized by the extent to which they meet the CFS criteria.