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FRI0521 Reliability of An Omeract Rheumatoid Arthritis Tenosynovitis Scoring System for Wrist and Hand

Background Tenosynovitis in the hand occurs frequently and early in rheumatoid arthritis (RA) and sensitive outcome measures are important to assess and monitor the inflammatory activity. Magnetic resonance imaging (MRI) can visualize tenosynovitis and a semiquantitative scoring system for tenosynovitis in the hand has previously been suggested1. However, it did not include the metacarpophalangeal (MCP) flexor tendons. Furthermore, each increment of the scale covered a broad interval of tenosynovitis severity, potentially improving reliability but with a risk of reducing sensitivity to change over time. Objectives To assess the intra- and inter-reader agreement of a proposed OMERACT tenosynovitis scoring system in the wrist and MCP flexor tendons in the hands of RA patients. Methods Axial T1-weighted pre- and post-contrast fat-suppressed MR image sets (0.8mm slice thickness) of the hand of 43 patients receiving rituximab were obtained at baseline and after 3 (n=5), 6 (n=8), 9 (n=15) or 12 (n=15) months. The images were read and scored twice on separate days with intermediate re-randomization and re-anonymization by 4 readers blinded to patient data but not to chronology. The tendons of 6 extensor and 3 flexor tendon compartments of the wrist and 4 flexor tendon compartments of the 2nd to 5th MCP joints were assessed. Tenosynovitis was defined as peritendinous effusion (PE) or post-contrast enhanced tenosynovial proliferation (ETP) on 3 consecutive slices. Pathologies were measured perpendicularly to the tendon at the thickest point of the effused or enhanced tenosynovium. Tenosynovitis was scored as follows: 0: no PE or ETP, 1: >0 but <1.5mm PE or ETP, 2: ≥1.5 but <3mm PE or ETP, 3: ≥3mm PE or ETP. Change in tenosynovitis over time was assessed using descriptive statistics and the Wilcoxon signed-rank test. Intra- and inter-reader agreement was calculated using single measure and average measure intra-class correlation coefficients (ICC), percentage of exact and close agreement (PEA and PCA) and the smallest detectable change (SDC). Results The mean (SD) change in tenosynovitis score between baseline and follow-up was -1.38 (2.84) for wrist, -0.94 (1.85) for MCP flexor tendons and -2.31 (4.63) for total score (all p<0.01). Intra- and inter-reader ICC for status scores were very good in all readers for all parameters (except baseline scores in the MCP region in 1 reader). Intra-reader ICC for change scores were good to very good in all readers for all parameters, and inter-reader ICC for status and change scores were very good in all readers for all parameters. Intra-reader PEA for status and change scores was above 57% and PCA was above 95% for all parameters. Inter-reader PEA was above 40% and PCA was above 81% for all parameters. Intra-reader SDC was below 3.0 for all parameters, except for total score in 1 reader (3.04). Inter-reader SDC was below 2.0 for all parameters (table 1). Conclusions The proposed OMERACT tenosynovitis scoring system showed high intra- and inter-reader agreement for wrist and MCP tendons and is a reliable tool for MRI-assessment of tenosynovitis in the RA hand, underpinning its likely responsiveness in subsequent randomized controlled trials. References Haavardsholm et al. Ann Rheum Dis 2007;66(9):1216–20 Disclosure of Interest None declared