Objective: To determine the frequency of subclinical synovitis on musculoskeletal ultrasonography (MSUS) in juvenile idiopathic arthritis (JIA) and correlate patient- and provider-reported outcome measures with MSUS synovitis.
Method: JIA patients with an active joint count (AJC) of >4 underwent a 42-joint MSUS performed at baseline and 3 months. B-mode and power Doppler images were obtained and scored (range 0-3) for each of the 42 joints. Outcomes evaluated included physician global assessment of disease activity (PhGA), patient global assessment of disease activity (PtGA), patient pain, Childhood Health Assessment Questionnaire (C-HAQ), and AJC. Subclinical synovitis was defined as synovitis detected by MSUS only. Generalized estimation equations were used to test the relationship between clinical arthritis (positive/negative) and subclinical synovitis (positive/negative). Spearman's correlation coefficients (rs ) were calculated to determine the association between MSUS synovitis and patient- and physician-reported outcomes.
Results: In 30 patients, subclinical synovitis was detected in 30% of joints. Clinical arthritis of the fingers, wrists, and knee joints was significantly associated with MSUS synovitis in these joints. PtGA and the C-HAQ had a moderate (rs = 0.44, P = 0.014) to weak (rs = 0.37, P = 0.045) correlation with MSUS synovitis. There was a statistically significant strong correlation between MSUS synovitis and PhGA (rs = 0.61, P = 0.001), but a weak correlation with AJC (rs = 0.37, P = 0.048) at the follow-up visit.
Conclusion: Subclinical synovitis was commonly observed in this cohort of JIA patients. The fair-to-moderate correlation of MSUS synovitis with patient- and provider-reported outcomes suggests that MSUS assesses a different, possibly more objective, domain not determined by traditional JIA outcome measurements.
© 2022 The Authors. Arthritis Care & Research published by Wiley Periodicals LLC on behalf of American College of Rheumatology.