One Year Follow Up of MRI Evaluation Of RA Patients In Low Disease Activity: Ramris Evaluation And Predictive Factors of Structural Progression

F. Gandjbakhch1, V. Foltz1, A. Mallet2, P. Bourgeois1, B. Fautrel1 1Department of Rheumatology; 2Department of Statistics, GH Pitie Salpetriere - APHP, Paris, France

Background: Remission in Rheumatoid Arthritis (RA) is nowadays achievable. Magnetic Resonance Imaging (MRI) has been validated in RA patients with active disease, but has to be evaluated in RA patients in low disease activity (LDA) or remission.

Objectives: To evaluate MRI validity in RA patients in LDA by 1) determining the sources of variability of the RAMRIS scores and 2) searching the predictive factors of MRI structural progression in such patients.

Methods: 85 RA patients (based on 1987 ACR criteria) in low disease activity (DAS 44 <2.4) or in remission (DAS 44 <1.6) were evaluated at baseline, 6 months and 12 months by clinico-biological and MRI evaluation. MRI (Cscan ESAOTE 0.2 T) of the dominant hand were performed and analyzed by 2 independent rheumatologists, blindly from clinical and biological data, according to the RAMRIS score and the MRI OMERACT group recommendations. One of the observers realized a second reading of the baseline MRI images, blindly from previous results. MRI validity was assessed by evaluating inter-rater and intra-rater reliabilities and analyzing agreement on Bland and Altman plots. A mixed model analysis allowed to determine estimations of baseline RAMRIS erosion, oedema and synovitis scores and to analyze sources of variability of the MRI examination. Structural progression was determined by the estimation of the difference of the RAMRISerosion score between baseline and one year. The smallest detectable difference (SDD) enabled to determine patients with structural progression. Predictive factors of structural progression were investigated by stepwise logistic regression.

Results: Patients characteristics were 85% female, mean aged 50 years, with mean disease duration 35 months, 63% were rheumatoid factor positive and 64% antiCCP antibodies positive, mean DAS 44 was 1.5. Inter-rater and intra-rater reliabilities were good to excellent (table), agreements on Bland and Altman plots were satisfactory and MRI structural progression could be detected after one year follow-up. There was no significant difference in the MRI findings between the LDA and remission groups. Presence of bone marrow oedema (BMO) at baseline appeared as a predictive factor of RAMRIS erosion change (OR=1.248 [1.091-1.429], p=0.0013, AUC=0.78). MRI wrist evaluation appeared more interesting than MCP evaluation with good inter-rater and intra-rater reliabilities, high frequencies of MRI abnormalities and presence of bone marrow oedema

Conclusion: Even in LDA/remission state, MRI evaluation appeared as a reliable imaging technique, enable to detect structural progression. Presence of BMO at baseline appeared as a predictive factor of structural progression. MRI examination of patients in LDA/remission should focus on wrists.

Disclosure of Interest: None declared

Citation: Ann Rheum Dis 2010;69(Suppl3):309

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