Evaluation of ILAR classification criteria for juvenile idiopathic arthritis in Spanish children

Objective. To evaluate the proposed International League of Associations fo r Rheumatology (ILAR) classification criteria for juvenile idiopathic arthr itis in a cohort of Spanish children. Methods. One hundred twenty-five patients with chronic arthritis were categ orized according to one of the traditional classifications and the proposed ILAR classification system after at least 6 months of disease. The traditi onal classifications included the European League Against Rheumatism (EULAR ) criteria for pauciarticular, polyarticular rheumatoid factor (RF) negativ e, and systemic juvenile chronic arthritis (JCA), as well as for RF+ polyar thritis; the Vancouver criteria for juvenile psoriatic arthritis (JPsA), an d the European Spondylarthropathy Study Group (ESSG) preliminary criteria f or juvenile spondyloarthropathy (JSpA). Results. The ILAR criteria classified 106/125 patients (84.8%). All patient s with systemic and polyarticular JCA, RF+ polyarthritis, and definite juve nile psoriatic arthritis were reclassified in the corresponding ILAR catego ry. In contrast, only 80% of pauciarticular JCA and 47% of JSpA patients co uld be allocated to the ILAR oligoarthritis (47/59 patients, 35 persistent and 12 extended) and enthesitis related arthritis (ErA, 8/17 patients) cate gories. Two children with probable PsA were reclassified in the RF- polyart hritis category. Nineteen patients (15.2%) were allocated to the ILAR "othe r arthritis" group, 13/19 because they did not fulfill criteria for any of the other categories ( 12 due to family history of psoriasis and one becaus e of family history of HLA-B27 associated disease). The remaining 6 patient s met criteria for 2 categories, RF- polyarthritis and either ErA (n = 5) o r PsA (n = 1). No differences other than family history of psoriasis were f ound in any of the variables studied between pauciarticular JCA patients cl assified in the oligoarthritis (n = 47) and those in the "other arthritis" (n = 11) ILAR categories. Conclusion. The proposed ILAR criteria allocated 84.8% of the patients clas sified by traditional criteria. Family history of psoriasis (n = 12) and po lyarticular onset of disease in patients with ErA (n = 5) were responsible for most of the exclusions from other ILAR categories.