Diagnostic criteria of rheumatoid arthritis in children. Proposed criteria for controlled clinical studies.

Several different sets of diagnostic criteria of rheumatoid arthritis in children are in practical use. The criteria most widely applied are discussed here, especially with regard to clinical studies. Reasons are presented for the selection of criteria used in the present controlled clinical studies on rheumatic children in Oslo. Three modifications were made in the North-American criteria: 1) disease onset before 16 years of age; 2) persistent arthritis for more than 3 months; 3) biopsy is preferable in monarticular cases, except in patients with chronic iridocyclitis.