Denmark, and Iceland. The cases were collected during one and a half years, beginning 1 July 1997. Method-Clinical variables (including those constituting the EULAR and ILAR criteria) and laboratory findings were registered longitudinally for each patient by paediatricians experienced in paediatric rheumatology. A database was constructed specifically for this purpose. In this study clinical findings and laboratory data from the first 6 months (for certain variables also for the first 12 months) were considered. Results-322 patients qualified for classification according to the ILAR criteria. Of those 322 patients, 291 had a disease duration of >3 months and were classified according to the EULAR criteria. Thus, 31/322 (10%) children were diagnosed only according to the ILAR criteria. 15% of the patients did not fulfil ILAR criteria for any of the categories and 6% fulfilled criteria for more than one category. As an example of the eVect of diVerent classification systems in our study, 160/ 322 were classified as oligoarticular by ILAR criteria and 184/291 by EULAR criteria. Conclusion-The qualifications for the ILAR criteria are diVerent from those of the EULAR criteria, which makes simple comparison neither possible nor scientifically relevant. One possibility is to study the construct validity of the respective criteria to give us a better idea of the classification and its consequences.
Juvenile spondyloarthropathies:checking criteria for diagnosis and classification at the start and after 6 months of disease
