Evidence of disordered symptom appraisal in fibromyalgia: increased rates of reported comorbidity and comorbidity severity.

OBJECTIVE Using a large series of unselected consecutive patients, to investigate whether patients with fibromyalgia differ from those with rheumatoid arthritis (RA) or osteoarthritis (OA) in the number of reported comorbid conditions and in their perceived importance, and thereby to investigate differences in symptom appraisal and somatization. METHOD In a clinical care setting, 1,298 patients with fibromyalgia and 2,396 with RA or OA participating in longitudinal data bank research as part of their routine medical care completed questionnaires concerning the presence or absence of 23 comorbid conditions, and then rated the current importance of each condition to them. Additional information concerning psychological factors and disease severity was also obtained. RESULTS In analyses adjusted for age and sex, patients with fibromyalgia reported more conditions (4.5 vs. 3.1) than those with RA or OA. In 17 of 23 conditions, the condition was more commonly reported in fibromyalgia than in RA or OA. In 20 of the 23 conditions, the importance attached to the conditions by fibromyalgia patients exceeded that of the importance attributed by RA/OA patients. After adjustment for anxiety, statistical differences between the groups for importance was lost for 6 conditions. CONCLUSIONS Fibromyalgia patients report more medical conditions and report that they are more important to them than do patients with RA or OA. These differences extend to conditions that might be expected to cause symptoms, as well as to those that are usually symptom free. These data suggest that, on average, patients with fibromyalgia appraise medical symptoms and their importance differently from patients with other rheumatic conditions.