Background Ultrasonography (US) is a sensitive method for synovitis detection in clinical practice but interobserver variation in both acquisition and image intepretation is still a key concern . Various semiquantitative synovitis scoring methods have been proposed in the past for B-mode and PDUS. Recently, the OMERACT US Task Force also proposed the EULAR-OMERACT PDUS composite scoring which had moderate to excellent reliability . However, this has not been tested formally outside of the steering group.
Objectives The objective was to evaluate if a collegiate small group consensus would improve US synovitis assessment and scoring in patients with rheumatoid arthritis, in both still images and in image acquisition.
Methods Eight rheumatologists from Singapore participated in a 1 day consensus meeting in November 2012, divided into (i) still-image interpretation and consensus followed by (ii) image acquisition and interpretation, according to definitions and synovitis scoring rules endorsed by OMERACT and TUI (Targeted Ultrasound Initiative). Interobserver reliability of semiquantitative scoring in B-mode, Power Doppler (PDUS) and EULAR-OMERACT PDUS composite score was assessed by intraclass correlation co-efficient (ICC). Agreement at the joint region level was calculated using prevalence-adjusted-biased-adjusted-kappa (PABAK).
Results For B-mode still images, ICC was good at 0.75 (95%CI 0.66-0.82) while for PDUS images this was excellent; ICC=0.88 (95%CI 0.83-0.92). During image acquisition and interpretation, B-mode scoring showed ICC=0.75 (95%CI 0.66-0.84) while for PDUS the ICC was lower at 0.59 (95%CI 0.48-0.72). The ICC for EULAR-OMERACT PDUS composite synovitis scoring was good at 0.77 (95%CI 0.68-0.85). At the joint level, agreement varied with PABAK being excellent in the small joints of the hands but poor to fair in the wrists, elbows, ankles and MTP, and no agreement at the knees (PABAK range -0.34 to 0.85).
Conclusions A consensus meeting between colleagues was useful in improving interobserver variation in synovitis scoring by ultrasonography, but agreement in non-hand joints is still a problem, requiring further standardisation.
Cheung PP, Dougados M, Gossec L. Reliability of ultrasonography to detect synovitis in rheumatoid arthritis: a systematic literature review of 35 studies (1415 patients). Arthritis Care Res (Hoboken) 2010; 62:323-34.
Naredo E, Wakefield R, Iagnocco A, et al. The OMERACT Ultrasound Task Force - Perspectives. J Rheumatol 2011;38:2063-7.
Disclosure of Interest None Declared