VALORE PREDITTIVO DELL’ECOGRAFIA MUSCOLOSCHELETRICA NEI PAZIENTI AFFETTI DA ARTRITE IDIOPATICA GIOVANILE IN REMISSIONE CLINICA

Background: the accurate assessment of remission status in JIA patients is of utmost relevance to taper medications and prevent side effects from their long-term administration. In RA patients in clinical remission (CR), musculoskeletal ultrasound (MSUS) allows to detect persistent joint inflammation (subclinical synovitis), which predicts disease flare and structural damage progression. Although subclinical synovitis has been reported in a substantial proportion of JIA patients with inactive disease, its prognostic value is still being defined. Objectives: 1) to investigate the prevalence of MSUS-detected subclinical synovitis in JIA patients in CR; 2) to establish which and how many joints should be scanned to reliably assess remission; 3) to evaluate the persistence of subclinical synovitis over the time; 4) to investigate whether subclinical synovitis entails a risk of disease flare and whether it should affect the therapeutic strategy. Methods: 135 consecutive JIA patients who met the Wallace criteria for CR were included in this 3-years prospective study. All patients underwent MSUS assessment of 56 joints at study entry and at 6 months follow-up visit. Joints were scanned for synovial hyperplasia, joint effusion and Power Doppler (PD) signal by two independent ultrasonographers. Patients were followed clinically for 3 years. A flare of synovitis was defined as a recurrence of clinically active arthritis. The association between clinical and MSUS variables with flare, was evaluated by adjusted logistic regression models. Results: 135 patients (78.5% F; median age 11.3 y; median disease duration 5.7 y; median CR duration 1.4 y) were included. Fifty-seven/135 (42.2%) patients had persistent oligoarthiritis; 41/135 (30.4%) extended oligoarthiritis; 32/135 (23.7%) polyarthiritis; 5/135 (3.7%) systemic arthritis. Seventy-eight/135 (57.7%) patients were in CR on medication. Subclinical synovitis was detected in 32/135 (23.7%) patients and in 53/7560 (0.7%) joints. Subclinical tenosynovitis was present in 20/135 (14.8%) patients. Subclinical synovitis was found more frequently in the ankle and wrist joints. 58.6% of patients showed persistent subclinical synovitis at 6 month follow up MSUS examination. During the 3-year follow up 45/135 (33.3%) patients experienced a disease flare (median survival time 2.2 y). PD positivity in tendons was the stronger independent risk factor of flare on multivariable regression analysis (HR: 4.8; P=0.04). Other predictors of flare were the JIA subtype (oligo-extended form: HR: 2.3; P=0.031) and the status of CR on medication (HR: 3.7; P=0.002). Conclusion: our results confirm that MSUS is more sensitive than clinical evaluation in the assessment of persistent synovial inflammation in JIA patients. Subclinical tenosynovitis was the best predictor of disease flare. To date, the role of tenosynovitis in the diagnosis and prognosis of JIA has been poorly investigated. Our results further support the role of MSUS, especially of the wrist and the ankle, in monitoring JIA patients in clinical remission and to predict disease flare. References: De Lucia O, et al. Baseline ultrasound examination as possible predictor of relapse in patients affected by juvenile idiopathic arthritis (JIA). Ann Rheum Dis. 2018 Oct;77(10):1426-1431. Filippou G, et al. The predictive role of ultrasound-detected tenosynovitis and joint synovitis for flare in patients with rheumatoid arthritis in stable remission. Results of an Italian multicentre study of the Italian Society for Rheumatology Group for Ultrasound: the STARTER study. Ann Rheum Dis 2018;77:1283-9.