Abstract
Methods: 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.
Results: 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.
Conclusion: 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concentrations of MRP8/MRP14 in clinical inactive arthritis may help to identify patients in whom MTX can be safely withdrawn after remission is achieved.
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Figure 1 .
Duration of remission. A survival analysis showed that patients after early discontinuation of MTX (group 1) had neither earlier flare ups nor more relapses than patients with late discontinuation (group 2). Point 0 indicates the time when MTX was withdrawn. Ticks in the graphs for both groups indicate censored data for patients with subsequent follow up of <36 months. A log rank analysis confirmed that the difference between both groups was not significant (p = 0.35).
Figure 2 .
Serum levels of MRP8/MRP14. (A) MRP8/MRP14 concentrations were analysed in 22 patients with oligoarticular and polyarticular JIA before and after the start of MTX treatment. There was a significant difference between serum concentrations in active disease before starting treatment with MTX and in inactive disease after successful treatment, respectively. Box plots show median, mean (bold line), 25th and 75th centiles. Error bars indicate 5th and 95th centiles (**p<0.001). (B) MRP8/MRP14 concentrations were analysed in serum from patients in remission, obtained at the time when MTX treatment was stopped. Two groups of patients were compared according to their outcome within one year after withdrawal of MTX. Serum levels were significantly higher in patients who had a relapse within the following year than in patients who stayed in stable remission. Data points show individual MRP8/MRP14 serum concentrations. The dashed line indicates a cut off point at 250 ng/ml with a sensitivity to detect risk for a relapse of 100%, while specificity was 70% (**p<0.01).