Assessment of synovitis to predict bone erosions in rheumatoid arthritis

Although rheumatoid arthritis (RA) is traditionally considered as the prototype of destructive arthritis, the course of the disease varies considerably, with some patients experiencing more rapid progression of joint damage and disability than others. Given the increasing availability of treatment targets and options, timely recognition of individual's outcomes could allow therapeutic allocation according to personalized benefit-risk profiles. Research efforts are thus increasingly focused at discovering predictive markers that could identify patients with aggressive, rapidly progressive disease and poor prognosis. As joint destruction in RA is the result of the cumulative burden of inflammation, variables reflecting the severity of synovitis and its persistence over time might refine our ability to build early prognostic algorithms. The goal of this article is to review the clinical implications of the assessment of synovitis in relation to radiographic outcomes. Traditional and novel assessment tools will be discussed, including clinical measures, imaging techniques and tissue biomarkers. Achievements in the field of synovial tissue analysis and peripheral blood biomarkers of synovitis represent only the first steps of ongoing progress, which still need to be integrated into the phenotypic heterogeneity of RA