Pain mystery score beliefs: a comparison of fibromyalgia and rheumatoid arthritis.

Objectives. To compare the mysteriousness scores of the Pain Beliefs and Perceptions Inventory in fibromyalgia. Methods. Two cohorts of patients, one with fibromyalgia (FM) and one with rheumatoid arthritis (RA), completed the Mystery Scale component of the Pain Beliefs and Perceptions Inventory to determine whether subjects in the two diagnostic groups had significantly different scores on the Mystery Scale. Results. A total of 126 subjects (64 FM, 62 RA) completed all questionnaires. The FM group had a greater percentage of female subjects, more severe pain, more severe anxiety, more severe depression, and a higher perceived injustice score. When the RA and FM group scores for the Mystery Scale were adjusted for age, sex, pain severity, HADS scores, and perceived injustice scores, the FM group still had a higher Mystery Scale score. Discussion. Fibromyalgia is associated with a higher level of perception of mysteriousness in the Pain Beliefs and Perceptions Inventory than is seen with rheumatoid arthritis. This difference appears to be independent of levels of pain, depression, anxiety, and perceived injustice. This sense of mysteriousness may reflect a lack of understanding of pain in fibromyalgia as previously reported and may be an area to be addressed in therapy.