Validation of the Pediatric Arthritis Ultrasound Scoring System for the Elbow, Wrist, and Finger Joints in Children with Juvenile Idiopathic Arthritis

Objective We aimed to validate the Pediatric Arthritis Ultrasound Scoring System (PAUSS) for upper extremity joints in children with juvenile idiopathic arthritis (JIA). Methods Children with JIA were evaluated for elbow, wrist, or finger arthritis by clinical examination (CE) and musculoskeletal ultrasound (MSUS) with images scored according to the joint‐specific PAUSS. A subset of children received contrast‐enhanced magnetic resonance imaging (ceMRI) of the affected joint(s). The performance of the PAUSS as a measure of arthritis activity was compared to CE and ceMRI, using ceMRI as reference standard. Results Seventy‐five children contributed 44 elbows, 55 wrists and 106 fingers for MSUS and 15 elbows, 16 wrists and 40 fingers for ceMRI. B‐mode PAUSS scores for the finger joints demonstrated moderate correlations with CE findings of arthritis while the PAUSS‐elbow noted a strong correlation. PAUSS scores for all joints showed a sensitivity of 75‐94% in detecting synovitis when compared to ceMRI and good to excellent diagnostic accuracy for elbow and finger arthritis. The addition of MSUS to CE markedly improved the sensitivity of CE to 92‐100%. The PAUSS and ceMRI scores for assessment of disease severity had strong correlation for each specific joint (r=0.65‐0.84, p≤0.005). Conclusion There is moderate to high sensitivity and diagnostic accuracy of the PAUSS in detecting synovitis in elbow, wrist, and finger joints, as well as a strong correlation of the PAUSS severity scores with the ceMRI severity scores, providing strong support that the PAUSS enhances the clinical assessment of disease activity in children with JIA.