ABNORMAL ILLNESS BEHAVIOR IN CHRONIC FATIGUE SYNDROME AND MULTIPLE-SCLEROSIS

Objective-To investigate the presence of abnormal illness behaviour in patients with a diagnosis of chronic fatigue syndrome. Design-A cross sectional descriptive study using the illness behaviour questionnaire to compare illness behaviour scores and illness behaviour profiles of patients with chronic fatigue syndrome and patients with multiple scl erosis. Setting-A multidisciplinary fatigue clinic and a teaching hosp ital neurology outpatient clinic. Subjects-98 patients satisfying the Oxford criteria for chronic fatigue syndrome and 78 patients with a di agnosis of multiple sclerosis. Main outcome measure-Responses to the 6 2 item illness behaviour questionnaire.Results-90 (92%) patients in th e chronic fatigue syndrome group and 70 (90%) in the multiple sclerosi s group completed the illness behaviour questionnaire. Both groups had significantly high scores on the general hypochondriasis and disease conviction subscales and significantly low scores on the psychological versus somatic concern subscale, as measured in relation to normative data. There were, however, no significant differences in the subscale scores between the two groups and the two groups had identical illnes s behaviour profiles. Conclusion-Scores on the illness behaviour quest ionnaire cannot be taken as evidence that chronic fatigue syndrome is a variety of abnormal illness behaviour, because the same profile occu rs in multiple sclerosis. Neither can they be taken as evidence that c hronic fatigue and multiple sclerosis share an aetiology. More needs t o be known about the origins of illness beliefs in chronic fatigue syn drome, especially as they are important in determining outcome.