The major purpose of this study was to compare the frequency of the occurrence of DSM-III diagnoses in patients with primary fibromyalgia syndrome, patients with rheumatoid arthritis, and subjects without pain.
Thirty-five patients with primary fibromyalgia, 33 patients with rheumatoid arthritis, and 31 nonpatients without pain were blindly assessed for psychiatric diagnoses with the Psychiatric Diagnostic Interview.
Data from this interview revealed no group differences in terms of lifetime history of any psychiatric disorders, including major depression, somatization disorder, or anxiety-based disorders. Analysis of the auxiliary symptoms of depression on the Psychiatric Diagnostic Interview revealed that the patients with fibromyalgia did not report a higher frequency of vegetative signs of depression. However, analysis of the somatization scale revealed an interaction between medical and psychiatric diagnoses: patients with primary fibromyalgia syndrome and a psychiatric history endorsed significantly more somatic symptoms than did patients with rheumatoid arthritis or subjects without pain, and fibromyalgia patients without a psychiatric history were no more likely to endorse somatic symptoms than were arthritis patients or subjects without pain.
The Psychiatric Diagnostic Interview data failed to discriminate in any major way between primary fibromyalgia syndrome (a disorder with no known organic etiology) and rheumatoid arthritis (a disorder with a known organic etiology). Therefore, these data do not support a psychopathology model as a primary explanation of the symptoms of primary fibromyalgia syndrome.