To investigate whether prolonged methotrexate (MTX) treatment after induction of remission influences the subsequent duration of remission in patients with juvenile idiopathic arthritis (JIA), and to analyse the usefulness of myeloid related proteins 8 and 14 (MRP8/MRP14) as predictive markers for the stability of remission at the time when MTX is withdrawn.
Twenty five patients with oligoarticular and polyarticular JIA who received MTX to induce remission were followed up. MTX treatment was stopped after a mean of 3.8 months (group 1) or 12.6 months (group 2) after remission was documented. Differences in the number of relapses between these groups were looked for. Additionally, MRP8/MRP14 were analysed by ELISA in 22 patients.
No difference was found in the number of relapses between patients with prolonged or early discontinued MTX treatment. Patients who were in stable remission had significantly lower MRP levels when MTX was discontinued than patients with relapses. With a cut off point for MRP8/MRP14 at 250 ng/ml, sensitivity and specificity were 100% and 70%, respectively.
Longer duration of MTX treatment after induction of remission does not generally improve the status of remission in patients with JIA. Residual synovial inflammation seems to influence the rate of relapses after discontinuation of MTX treatment. MRP8/MRP14 indicate residual activity even in the absence of other laboratory or clinical signs of continuing inflammation. Normal serum concentrations of MRP8/MRP14 in clinical inactive arthritis may help to identify patients in whom MTX can be safely withdrawn after remission is achieved.