Background: Anxiety about illness leading to restriction of activity and physical deconditioning has been hypothesized to contribute to the chronicity of fatigue. Pathological symptom attributions, personality traits, and depression have all been hypothesized to contribute to illness worry.
Methods: We compared 45 chronic fatigue syndrome (CFS) and 40 multiple sclerosis (MS) outpatients using a battery of psychometric instruments comprising the 12-item Illness Worry scale, the Symptom Interpretation Questionnaire (SIQ), the NEO Five-Factor Inventory (NEO-FFI), and a modified version of the SCL-90R Depression scale.
Results: There was no difference between the two diagnostic groups on neuroticism, depressive symptoms, as well as the three scales of the SIQ. On the illness worry index, the CFS group had significantly higher scores than the MS group. This difference was due to items tapping vulnerability to illness and the perception that others are not taking their illness seriously. Somatic attributional style, neuroticism, depressive symptoms, and age were all significant predictors of illness worry in both CFS and MS patients.
Conclusions: Somatic attributions, neuroticism, and depression all contribute to illness worry in chronic illness. However, these factors do not account for the higher levels of illness worry in CFS as opposed to MS, which may be due to other specific cognitive and social interactional processes.