Reliability and Availability of the 2017 EULAR-OMERACT Scoring System for Ultrasound Synovitis Assessment: Results From a Training and Reading Exercise.

Objective: To evaluate the availability and reliability of the European League Against Rheumatisms Outcome Measures in Rheumatology Synovitis (EULAR-OMERACT) scoring system among radiologists with different levels of musculoskeletal ultrasound (US) experience in assessing synovitis in patients with rheumatoid arthritis (RA).

Method: The patients with RA were retrospectively recruited from January 2020 to March 2022. Five radiologists with different levels of US experience were recruited for the reader study (R1-5), which included two parts. The participating radiologists first read 120 gray-scale (GS) and 120 Doppler US images twice, before and after a standard training program. In the first part, they semi-quantitatively scored the images from 0 to 3 based on the EULAR-OMERACT scoring system. In the second part, they read and scored 165 paired GS and Doppler images two times in 1 month using the EULAR-OMERACT scoring system. The correlation between the sum of the GSUS and power Doppler US (PDUS) image scores and the clinical scores was assessed.

Result: The intra-rater agreement of the five radiologists was good for the EULAR-OMERACT scoring system, with κ ranging from 0.72 to 0.94 for GSUS and from 0.81 to 0.97 for PDUS. The inter-rater agreement among the experts was good to very good in the EULAR-OMERACT scoring system (κ: 0.76-0.94 for GSUS and 0.80-0.96 for PDUS). The sum of the GSUS and PDUS scores in the EULAR-OMERACT scoring system was moderate to highly positively correlated with the clinical scores (ρ of GSUS: 0.58-0.79, ρ of PDUS: 0.57-0.70 for disease activity score in 28 joints C-reactive protein) after training.

Conclusion: The EULAR-OMERACT scoring system is a reliable method for evaluating synovitis in RA and shows potential for disease assessment and follow-up in patients with RA.