LAUSR

OBJECTIVES Juvenile idiopathic arthritis (JIA) is characterised by a chronic disease course. Once patients achieve a state of inactive disease, there are no established biomarkers to predict the further course of inflammation for these patients. Therefore, the purpose of this study was to quantify serum biomarkers during quiescent disease to evaluate their use in identifying JIA-patients at risk for future disease flare. METHODS Patients with non-systemic JIA reaching inactive disease status were divided into 2 groups: 92 patients with future active disease after a median period of 6 months (range 3-9) and 80 patients with persistent inactive disease for the following period (median 11 months, range 7-16) according to the juvenile arthritis disease activity score (JADAS). Clinical parameters and serum levels of various biomarkers were measured in the state of inactive disease using immunoassays in both groups and were analysed for their potential to predict the further course of disease. RESULTS Soluble interleukin-2 receptor (sIL-2R) serum levels were significantly higher in patients with future active disease (p= 0.021), which especially applied to patients with rheumatoid factor (RF)-negative polyarticular and extended oligoarticular JIA (p< 0.001). Higher sIL-2R serum levels during inactive disease were associated with a greater number of active joints at future active disease. CONCLUSION Patients without clinical signs of disease activity already presented with increased sIL-2R serum levels several months before disease relapses, whereas conventional inflammation parameters were not elevated. Determination of sIL-2R serum levels during inactive disease may facilitate identifying patients with subclinical disease activity at risk for future active disease.