Ultrasonography (US) studies carried out on joints of juvenile idiopathic arthritis (JIA) patients in clinical remission demonstrate the presence of subclinical synovitis. The significance of subclinical synovitis and the positive power Doppler (PD) signal on US in JIA in clinical remission is not well understood. The objectives of this study were to assess whether the changes detected by US in patients with JIA in clinical remission can predict disease flare and to evaluate factors associated with flare and joint damage over 30 months of follow-up.
A prospective study was performed with clinical and ultrasound evaluation in 34 joints of JIA patients in clinical remission. Clinical evaluation including physical exam, functional capacity and inflammatory markers was performed at baseline and every six months thereafter, for a total period of 30 months. US evaluation included presence of synovitis, PD signal and erosion at baseline and every 12 months thereafter. Subclinical synovitis was defined when there was synovitis with or without positive PD signal in US joints of patients in clinical remission. Flare was defined as any joint presenting clinical arthritis requiring therapy modification.
We evaluated a total of 35 patients, 28 (80%) girls, 14 (40%) persistent oligoarticular subtype, 12 (34.3%) oligoarticular extended and 9 (25.7%) polyarticular and 26 (74.3%) in remission on medication. Twenty (57.1%) patients flared. The risk of flare was five times higher in patients with positive PD signal and 14 times higher in patients in remission on medication. Regarding the assessment of joints after 6 months and 12 months of US evaluation, 70/3162 (2.2%) joints and 80/2108 (3.8%) joints flared, respectively. Joints with subclinical synovitis with positive PD signal flared more after 6 and 12 months. Twenty five of 2108 (1.2%) joints showed erosion over time. Joints with subclinical synovitis with or without positive PD signal showed more erosion.
Patients in remission on medication with subclinical synovitis with positive PD signal on US have a higher risk of flare, therefore they should be monitored closely during treatment. In the same way, joints with subclinical synovitis with or without positive PD signal should be monitored due to the risk of flare and joint damage.