Antiperinuclear factor in the diagnosis of juvenile rheumatoid arthritis.

The antiperinuclear factor (APF) was estimated by immunofluorescent microscopy in the sera of 32 children and adolescents with juvenile rheumatoid arthritis (JRA) in comparison to a group of 16 children and adolescents with other rheumatologic disorders and a group of 20 age-matched healthy subjects. The APF was detected in 17 children with JRA (53%), in only one patient in the group of other rheumatologic disorders (6%), and in 2 healthy children (10%). Accordingly, APF had a sensitivity of 53%, a specificity of 92%, and a diagnostic efficiency of 74% in our series. APF was found to have a higher diagnostic gain in rheumatoid factor (RF) seronegative cases than did the RF in APF negative cases, meaning a higher sensitivity of APF as compared to the RF. The APF seropositivity was neither altered by the use of corticosteroids nor influenced by the age, gender, duration of illness, or number of joints affected. Three out of 5 patients with JRA had the APF detected in their synovial fluid; they were running rather a severe course of illness. The use of the APF could be an aid in the diagnosis of JRA.