To assess the intra- and interreader reliability and the sensitivity to change of the Outcome Measures in Rheumatology Clinical Trials (OMERACT) Rheumatoid Arthritis Magnetic Resonance Imaging Score (RAMRIS) system on digital images of the wrist joints of patients with early or established rheumatoid arthritis (RA).
Ten sets of baseline and 1-year followup MR images of the wrists of patients with progressive changes on conventional hand radiographs were scored independently by 4 readers on 2 consecutive days, preceded by reader training and calibration. The MR images were acquired and scored according to the recommendations from the OMERACT MRI group. The intra- and interreader agreement (evaluated by intraclass correlation coefficients [ICCs]) and the sensitivity to change (evaluated by the smallest detectable difference [SDD]) were determined for scores of synovitis, erosion, and bone marrow edema status and for change scores.
Intrareader ICCs were generally very high, both for status scores (median baseline and followup 0.89 and 0.90 for synovitis, 0.91 and 0.90 for erosion, and 0.90 and 0.98 for edema) and for change scores (median 0.80 for synovitis, 0.96 for erosion, and 0.97 for edema). The SDDs were generally low, suggesting a high potential to detect changes. Interreader single-measure ICCs were high for status scores (mean baseline and followup 0.69 and 0.78 for synovitis, 0.83 and 0.73 for erosion, and 0.79 and 0.95 for edema) and for change scores (mean 0.74 for synovitis, 0.67 for erosion, and 0.95 for edema). The average-measure ICCs were > or =0.94 for all components of both the status scores and change scores.
The RAMRIS showed very good intrareader reliability, good interreader reliability, and a high level of sensitivity to change. The results suggest that the RAMRIS may be a suitable system for use in monitoring joint inflammation and destruction in RA.