Persistent Elevation of Fibrin D-Dimer Predicts Longterm Outcome in Systemic Juvenile Idiopathic Arthritis

Objective. We previously demonstrated that levels of fibrin d-dimer correlate with disease activity and response to therapies in systemic juvenile idiopathic arthritis (sJIA). We hypothesized that persistence of D-dieter elevation in the patterns previously described, but over a longer followup period, would signal poor outcome. Methods. We studied 31 children identified from 2 centers. Subjects were assigned a risk category based on their first obtained D-dieter concentration. Risk categories were based on results of our initial study, where normalization of D-dieter in patients no longer taking immunosuppressive therapy predicted good short-term outcome, and persistent D-dieter elevation while taking immunosuppressives predicted bad outcome (radiographic abnormalities, joint replacement surgery, or poor functional class) or a severe systemic manifestation. Outcome was determined at the last followup visit, a minimum of 2 years after measurement of the initial d-dimer level. Results. The 31 children were a mean 16.4 years old at an average of 8.8 years after their initial diagnosis. Ten children had a severe outcome during this period; all 10 had a study baseline risk category of "high." Of the 14 subjects who had a high risk category at study baseline, none had a mild outcome. Conclusion. Our study indicated that a paradigm of risk of severe disease based upon persistent elevation of fibrin d-dimer on first measurements (greater than a mean of 29 months in our initial study and at least 24 months in the additional subjects) is promising to predict poor longer-term outcome in sJIA. A larger prospective study is warranted to substantiate the preliminary data and assess the relative comparative value to other biomarkers and clinical endpoints. (First Release Dec 1 2008; J Rheumatol 2009;36:422-6; doi:10.3899/jrheum.070600)