Juvenile Fibromyalgia in Patients With Juvenile Idiopathic Arthritis: Utility of the Pain and Symptom Assessment Tool

To evaluate the proportion of children with juvenile idiopathic arthritis (JIA) who met criteria for comorbid juvenile fibromyalgia (FM) using the Pain and Symptom Assessment Tool (PSAT), and to identify clinical and demographic differences among JIA patients with and without juvenile FM.

Patients ages 11-17 years with JIA were recruited from 4 North American pediatric rheumatology centers. Each patient completed the PSAT. Additional clinical and disease activity measures included pain visual analog scale, patient global assessment of disease activity (PtGA) and physician global assessment of disease activity (PhGA), the Functional Disability Inventory (FDI), and the Pain Catastrophizing Scale in children.

Of 129 patients, 11 met criteria for juvenile FM. FDI scores were markedly higher in patients who tested positive for juvenile FM, with a mean of 24.8 compared to 6.9 in patients without juvenile FM (P < 0.001). Pain catastrophizing scores were also significantly higher, by ~14 points, in patients with juvenile FM. There was a significant tendency for patients to give higher disease activity scores than physicians, which was more marked among patients with juvenile FM. In patients with juvenile FM, PtGA scores exceeded PhGA scores by a mean of 3.7, compared to a mean of 0.7 among patients without juvenile FM (P < 0.001).

A minority of JIA patients (8.5%) met criteria for juvenile FM. This group demonstrated markedly more functional impairment. PtGA scores were strikingly higher than PhGA scores among patients with JIA who met juvenile FM criteria, suggesting that providers might consider a more expansive approach to chronic pain and non-musculoskeletal symptom assessment and treatment in JIA patients.