Toward an understanding of the long-term outcome of juvenile idiopathic arthritis.

Over the past four decades, a number of studies have evaluated the long-term outcome of juvenile idiopathic arthritis (JIA) and some of them have also attempted to identify early prognostic factors. This editorial addresses, by reviewing the surveys that have analyzed the outcome of JIA in term of clinical remission, physical disability, and radiographic damage, the clinical questions that are most relevant in this area of study. Altogether, the available data indicate that JIA is not a benign disease because a considerable number of patients still enter adulthood with persistently active disease and a significant proportion of them may develop severe physical disability. Among the different onset forms, the long-term outcome is best in persistent oligoarthritis and worst in RF-positive polyarthritis; the outcome of systemic arthritis is widely variable, perhaps reflecting the heterogeneity of this JIA subtype. The comparison of earlier studies with those published in the last decade shows a decline in the frequency of patients with severe physical disability over the years; however, the proportion of patients who enter adulthood with active disease does not seem to be diminished. Although there is considerable data on prognostic factors in JIA, prediction of long-term outcome early after disease presentation is still difficult because comparisons among studies are hindered for a variety of reasons. Thus, while a considerable body of data is accumulating, the definition of the long-term outcome of JIA remains imperfect. To increase the comparability of future analyses and to obtain generalizable information on the prognosis of JIA and its prediction, a great deal of effort should be directed toward standardizing the study design and the measurement of predictors and outcomes.