Objective: To evaluate the revised (Edmonton 2001) International League of Associations for Rheumatology (ILAR) classification criteria for Juvenile Idiopathic Arthritis (JIA) in a cohort of Spanish children.
Methods: One hundred twenty-five patients with chronic arthritis categorized according to traditional criteria and to the first revision of ILAR JIA criteria (Durban 1997) were reclassified according to the second JIA criteria revision (Edmonton 2001).
Results: Edmonton criteria allocated 92% of the patients classified by traditional criteria in their corresponding ILAR categories. Most patients with systemic (94%), pauciarticular (91%) and polyarticular (88%) juvenile chronic arthritis as well as those with juvenile spondyloarthropathy (94%) were reclassified in the corresponding ILAR categories. Two children with probable psoriatic arthritis (PsA) were reclassified in the rheumatoid factor-negative (RF-) polyarthritis category, whereas only one of 2 children with definite PsA could be allocated to the ILAR PsA class. Ten patients (8%) constituted the undifferentiated arthritis group, 8 because of psoriasis in a first-degree relative, one because of the presence of RF in a girl with oligoarthritis, and another because of psoriasis in a boy who was HLA-B27-positive. In comparison with the Durban JIA criteria the Edmonton revision decreased the number of patients whose arthritis fulfilled criteria in no category or in 2 or more categories (from 19 to 10), and delineated better the population included in the RF- polyarthritis category.
Conclusion: The Edmonton criteria made the ILAR classification more transparent and easy to apply. Family history of psoriasis was responsible for most allocations to the undifferentiated arthritis category (8/10).