RELATIONSHIP OF RHEUMATOID FACTOR TO AGE OF ONSET IN JUVENILE RHEUMATOID ARTHRITIS

In a prospective study of 110 children with juvenile rheumatoid arthritis, the incidence of rheumatoid factor was shown to be clearly related to age at onset. Only 3.8 per cent of children with onset before 4 years of age had positive tests by the latex fixation method, compared to 25.6 per cent with onset from 4 to 12 years of age and 77.8 per cent with onset between 12 and 16 years of age. These differences were confirmed by the SSC method, and the differences were statistically highly significant. Copyright © 1969 American College of Rheumatology