Abnormal ultrasound findings were common in patients with juvenile idiopathic arthritis (JIA) with clinically inactive disease, but these findings did not predict future symptom flares in up to 2 years of follow-up, according to research results published in The Journal of Rheumatology.
Compared with clinical examination, advanced tools such as ultrasound or magnetic resonance imaging (MRI) offer greater sensitivity for detecting active arthritis in patients with asymptomatic JIA, but the long-term significance of abnormal results is uncertain in the face of normal joint presentations. The investigators sought to determine the prevalence of abnormal ultrasound readings in a cohort of patients with JIA with inactive disease, and to assess the clinical significance and predictive value of these findings in terms of future flares.
Between August 2012 and August 2013, 40 children ≥4 years (median age, 10.7 years; median disease duration, 5.5 years; median inactive duration, 1.0 year) with inactive JIA were enrolled in a 2-year prospective study at a single tertiary center. Rheumatoid factor-negative polyarthritis (38%) and extended oligoarticular JIA (30%) were most common in this cohort.
Baseline and follow-up ultrasound imaging were performed at the knees, wrists, tibiotalar joints, and subtalar joints. Two pediatric musculoskeletal radiologists analyzed the findings. Through 24 months of follow-up, clinical and laboratory data were collected, including disease activity measures. A flare was defined as any joint demonstrating clinical synovitis according to American College of Rheumatology guidelines.
There were 18 individuals (45%) who had abnormal baseline ultrasound findings, including synovial thickening or joint effusion, in at least 1 of 8 joints examined. A total of 289 joints were analyzed, and 24 joints (8%) had at least 1 abnormal finding. Exclusion of power Doppler signals resulted in 14 abnormal findings in 9 patients (23%). Over the course of 24 months of clinical follow-up, 18 patients (45%) flared in 27 joints, predominantly the knee, but these flares were only correlated to abnormal baseline ultrasound signals in 4 total joints.
Despite the high prevalence, abnormal ultrasound results only had 15% sensitivity and 12% positive predictive value when they were evaluated against individual joint flares during follow-up. The predictive power of the second ultrasound, performed on 33 patients, was lower than that at baseline, with 11% sensitivity and 6% positive predictive value. Across all joints, the odds ratio of flares between participants with normal vs abnormal ultrasound results was not significant.
Study limitations included a lack of healthy controls, variable treatment regimens and clinical examination timing across patients, analysis of only 8 commonly affected joints, use of only a single-plane still image, lack of targeted imaging, and no comparison to MRI findings.
The clinical significance of the study findings remains uncertain. The authors recommended that future research involve larger longitudinal trials that comprise extensive data collection with repeated ultrasound evaluations, including the use of multiple views and dynamic assessments.
Zhao Y, Rascoff NE, Iyer RS, et al. Flares of disease in children with clinically inactive juvenile idiopathic arthritis were not correlated with ultrasound findings [published online April 1, 2018]. J Rheumatol. doi:10.3899/jrheum.170681