Magnetic resonance imaging-detected inflammation is associated with functional disability in early arthritis-results of a cross-sectional study.

OBJECTIVES: MRI sensitively detects inflammation, but the clinical relevance of MRI-detected inflammation is undetermined in early arthritis. Therefore, the aim of this cross-sectional study was to investigate the association between MRI-detected inflammation of hands and feet and functional disability in early arthritis. METHODS: Five hundred and fourteen early arthritis patients, consecutively included in the Leiden Early Arthritis Clinic, were studied. At baseline a unilateral 1.5 T MRI of the wrist, MCP and MTP joints was performed and functional disability was measured using the HAQ. MRIs were scored for tenosynovitis, synovitis and bone marrow oedema (BME) by two readers. The sum of these types of MRI-detected inflammation yielded the total MRI-inflammation score. Linear and nonlinear regression analyses were performed with HAQ as outcome. RESULTS: The total MRI-inflammation score was associated with the HAQ score (ß = 0.014, P < 0.001), as were tenosynovitis (ß = 0.046, P < 0.001), synovitis (ß = 0.039, P < 0.001) and bone marrow oedema scores (ß = 0.015, P < 0.001) separately. Analysing these three types of MRI-detected inflammation in one multivariable model revealed that only tenosynovitis was independently associated with the HAQ score (ß = 0.039, P < 0.001). Also after correction for age, gender, joint counts, CRP and auto-antibodies, this association remained significant (ß = 0.034, P < 0.001). MRI-detected inflammation at wrists or MCP joints associated significantly with impairments in hand functioning (e.g. difficulties with opening milk cartons or jars). Exploring the relation between MRI-detected inflammation and HAQ scores showed no evidence of a floor effect, suggesting that even low scores of MRI-detected inflammation are functionally relevant. CONCLUSION: MRI-detected inflammation, and tenosynovitis in particular, is associated with functional disability. This demonstrates the functional relevance of MRI-detected inflammation in early arthritis.