Prevalence of Juvenile Fibromyalgia Syndrome in Turkish Patients with Juvenile Idiopathic Arthritis: A Multicenter Study.

Objectives: To investigate the diagnostic prevalence of juvenile fibromyalgia syndrome (JFMS) causing widespread pain in patients with a diagnosis of juvenile idiopathic arthritis (JIA).

Methods: Patients with JIA from seven pediatric rheumatology centers in Türkiye were included. 2010 American College of Rheumatology criteria for fibromyalgia was utilized throughout a face-to-face interview. The Pain and Symptom Assessment Tool was used, and data were analyzed using the Widespread Pain Index and the Symptom Severity Scale. Patients were stratified into two groups: Group 1 (JIA with concomitant juvenile fibromyalgia) and Group 2 (JIA without juvenile fibromyalgia).

Results: A total of 313 patients with JIA were included, of whom 21 (6.7%) were found to have concomitant JFMS. In group 1, 71% (15 patients) were female and 29% (6 patients) were male, with a median age at JFMS evaluation of 16 years (range: 12.8-19). Among patients with JFMS, 62% (13 patients) were classified as having spondyloarthropathy (enthesitis-related arthritis or juvenile psoriatic arthritis), 28.5% (6 patients) as having oligoarticular JIA, and 9.5% (2 patients) as having polyarticular JIA. Seventeen patients (81%) were on medication, including five (24%) on biologics. The most common symptoms in the JFMS group were muscle pain and fatigue, followed by headache, nervousness, numbness, dizziness, acne, abdominal pain, and anorexia.

Conclusion: In JIA patients with chronic musculoskeletal pain, fatigue, headache, and irritability lasting more than three months, the possible diagnosis of JFMS should be considered in the clinical evaluation.