[Change of diagnosis and diagnostic category in patients with juvenile idiopathic arthritis within 7 years of follow-up].

Introduction: At least 50% of pediatric patients with Juvenile Idiopathic Arthritis (JIA) will require continued fo llow-up in adult rheumatology. The present International League of Associations for Rheumatology (ILAR) classification, currently under revision, differs from its classification of inflammatory arthritis in adults. Category changes have been reported in 10.8% of patients during follow-up.

Objective: To analyze JIA patients in follow-up for at least 7 years to detect diagnosis changes during transition to adult care, identifying factors of poor functional prognosis.

Patients And Method: Retrospective study based on medical records of JIA patients seen at the pediatric polyclinic of the Puerto Montt Hospital between 2005 and 2017, who were monitored for at least 7 years. Descriptive analysis was performed according to clinical variables: diagnostic category, evolution before diagnosis, clinical and serological activity, and evolution before starting drug therapy.

Results: We evaluated 18 pa tients, corresponding to 3 patients with persistent oligoarticular arthritis (OA), 1 with extended OA, 4 with polyarticular arthritis (PA) rheumatoid factor (RF) negative, 4 with PA RF positive, 5 with syste mic JIA, and 1 with psoriatic arthritis, all have had follow-up more than 7 years. 11 out of 18 patients transitioned to adult care. Three out of 11 patients changed diagnosis to Rheumatoid Arthritis (RA) plus another autoimmune disease such as Sjögren's Syndrome + Systemic Lupus Erythematosus, Immune thrombocytopenia, or unclassified autoimmune disease, and 5 out of 11 children changed ILAR category from OA to Juvenile Rheumatoid Arthritis, extended OA to PA RF negative, and 3 from Systemic arthritis to PA RF negative. Age of onset, polyarticular forms, delay in diagnosis, and the start of therapy were associated with sequelae and persistent inflammation.

Conclusions: Eight of the eleven JIA patients who transitioned to adult care changed their diagnosis or presented other autoimmune diseases. Some factors of poor prognosis must improve.