Background The Outcome Measures in Rheumatology Clinical Trials (OMERACT) scores are the most mature quantitation system for RA on digital images of the wrist and finger joints. However, the reliability of the OMERACT scoring system has low intra-reader validation. Several direct measuring techniques of synovial volume have been reported with good reproducibility, although a few reports demonstrated the responsibilities of changes of these measures to the treatments.
Objectives To compare responsibilities of the changes of OMERACT scores and MRI-derived synovial volume to the changes of disease activity score (DAS28-CRP).
Methods MRI data of the dominant affected wrist and finger joints were obtained from 40 joints of 8 RA patients who were treated with biologic agents at the baseline and one year after the treatment. DAS28-CRP was also assessed at baseline and 1 year. Wrist and 2nd to 5th metacarpophalangeal joints were scored using OMERACT scoring system and synovial volumes were measured at the same areas. Correlation of the changes of OMERACT score and synovial volume with the changes of DAS28-CRP were analyzed by Pearson correlation test.
Results At baseline, all patients had clinically active RA with mean DAS28-CRP score 3.75 ± 0.75. At 1 year DAS28-CRP was significantly reduced to 1.92 ± 0.54. OMERACT score and synovial volume were reduced from 48.0 to 41.3, and from 15.4 to 8.8 (milliliter), respectively. In each joint, synovial volume had good correlation (r=0.88) with OMERACT synovitis score. The changes of OMERACT synovitis score(r=0.28), OMERACT total (sum of synovitis, erosion and bone oedema) score(r=0.43) and synovial volume (r=0.30) showed positive correlations with the changes of DAS28-CRP.
Conclusions MRI synovial volume showed better correlation with clinical response to the treatment by biologic agents than OMERACT synovitis score. On the other hand, OMERACT total score showed better correlation with DAS28-CRP than synovial volume, probably due to the involvement of scores for bone erosion and bone oedema.
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Disclosure of Interest None Declared