PAIN PERCEPTION AND PAIN COPING MECHANISMS IN CHILDREN AND ADOLESCENTS WITH JUVENILE FIBROMYALGIA AND POLYARTICULAR JUVENILE IDIOPATHIC ARTHRITIS.

Objective: To measure and compare musculoskeletal pain in patients with juvenile fibromyalgia (JFM) and polyarticular juvenile idiopathic arthritis (JIA), and to evaluate and compare pain perception and pain coping mechanisms in these patients.

Methods: In this cross sectional study, we evaluated 150 children and adolescents, and their respective parents, from 3 different groups: JFM, polyarticular JIA, and healthy controls. Pain intensity and pain coping mechanisms were measured using specific questionnaires. Pain perception was evaluated according to three illustrations simulating situations that might cause pain: a shot, a bicycle fall, and social isolation. The patients' parents also filled out the questionnaires and provided a pain score that matched their child's perception of pain for each illustration.

Results: The highest pain scores, the lowest pain coping strategy scores, the highest pain perception scores for all three illustrations, and the worse health related to quality of life indicators were observed in the JFM group, when compared to the JIA and control groups. The same pattern was observed with their parents.

Conclusions: Patients with JIA and JFM behave differently in relation to pain perception and the development pain coping mechanisms. Pain should be evaluated from different perspectives for an individualized and efficient treatment of patients.