A study of erosive phenotypes in lupus arthritis using magnetic resonance imaging and anti-citrullinated protein antibody, anti-RA33 and RF autoantibody status

Objectives. The aims of this study were to investigate the extent of MRI-determined joint disease (erosion and synovitis) in SLE and to link this to autoantibody profiles known to be relevant to SLE, including ACPA, RF and anti-RA33 antibodies. Methods. Contrast-enhanced MRI of the hand and wrist was performed in 34 symptomatic SLE patients and in 15 RA patients with similar disease duration. Images were scored by two observers using the OMERACT rheumatoid arthritis MRI scoring (RAMRIS) system. Findings were correlated with clinical examination and autoantibody status. Results. Erosions were present at the wrist in 93% of SLE patients and at the MCP joints in 61% of SLE patients. Despite the high prevalence of MRI-determined erosion, only 8.8% of SLE patients were ACPA positive, although these patients had a higher burden of erosive disease. There was no positive correlation with anti-RA33 titres and erosion scores in the SLE patients, but there was a negative correlation with anti-RA33 titres and total bone oedema scores in the SLE patients. Ninety-three per cent of SLE patients had at least grade 1 synovitis at one or more MCP joints, and wrist joint synovitis was present in all the SLE patients. Conclusion. An MRI-determined joint erosive phenotype is common in SLE, even in ACPA-negative cases. The conventional radiographic observation that anti-RA33 is not positively associated with erosion in patients with RA was also found to be the case in SLE patients.