Validity of the rheumatoid arthritis MRI score applied to the forefeet using the OMERACT filter: a systematic literature review

OBJECTIVE: MRI depicts inflammation and structural damage in rheumatoid arthritis (RA). The validity of MRI-scoring of wrist-joints and metacarpophalangeal-joints according to the RA MRI score(RAMRIS) has been demonstrated. The Outcomes in Rheumatology Clinical Trials (OMERACT) RAMRIS Working Group recently called for validation of the RAMRIS of the metatarsophalangeal (MTP)-joints. Therefore, a systematic literature review was performed to test if the RAMRIS applied to the MTP-joints meets the OMERACT Filter of Truth, Discrimination and Feasibility. METHODS: Medical literature databases up to January 2018 were systematically reviewed for studies reporting on RAMRIS applied to MRI of the MTP-joints in RA. To be included, an article had to contain at least one MRI-feature (synovitis, bone marrow oedema (BME), tenosynovitis, erosion, joint space narrowing (JSN)) and one item from the OMERACT Filter: Truth (face, content and construct validity), Discrimination (test-retest reliability, ability to discriminate in trials, longitudinal construct validity and thresholds of meaning) and Feasibility. RESULTS: Of the 749 retrieved studies, 13 were included, of which 9 provided data on construct validity, 4 on discrimination (3 on reliability, 2 on longitudinal construct validity and 1 on ability to discriminate in trials) and none on feasibility. Construct validity was suggested for BME and erosions, but lacking for synovitis, tenosynovitis and JSN. Data for discrimination remain to be developed for all outcomes. CONCLUSION: According to the OMERACT Filter, the validity of the RAMRIS of the forefeet is insufficient in different aspects. A research agenda was determined.