Synovitis Common in Ultrasounds of RA Patients in "Remission"

June 25, 2014

Residual synovitis is often seen on ultrasounds of rheumatoid arthritis patients. It may hint at relapse.

Nguyen H, Ruyssen-Witrand A, Gandjbakhch F, et al., Prevalence of ultrasound-detected residual synovitis and risk of relapse and structural progression in rheumatoid arthritis patients in clinical remission: a systematic review and meta-analysis. Rheumatology (2014) doi: 10.1093/rheumatology/keu217 (First published online: June 13, 2014)

Many rheumatoid arthritis (RA) patients who meet the criteria for clinical remission actually show residual joint inflammation on ultrasound, judging from a new meta-analysis. The researchers from France contend that this is a harbinger of structural progression.

They note that, while ultrasound or MRI can directly visualize synovitis and bone damage, in contrast to European League Against Rheumatism (EULAR) guidelines, there’s no consensus in the US about the preferred mode of joint imaging for RA patients in remission.

Their systematic review of English- and French-language studies conducted between 2001 and 2012 among 1,618 patients, most of them in remission, found a 44% prevalence of synovial hypertrophy or joint effusion  on power Doppler (PD) ultrasound. The prevalence was over 80% with gray-scale ultrasound, but Doppler produces better results.

The researchers say the prevalence is comparable no matter which remission criteria are used or how many joints are assessed. The prevalence is greater among patients with long-standing RA, where synovial tissue can become chronically thickened and less reversible, the authors note.

Only three studies directly assessed the association between the number of joints with ultrasound-detected synovitis and later progression, and all three found it to be significant.

The first meta-analysis of the impact of ultrasound-detected synovitis on the risk of relapse and structural progression, this study finds that use of power Doppler produces the most significant association. The odds ratio for patients with positive Doppler results was 3.2 for relapse and 9.13 for structural progression over a 2-year period. 

Interestingly, the prevalence of synovitis in the joints of the dominant hand is comparable to that seen in several other joints, including the knees and ankles, leading the authors to speculate that ultrasound of the hand alone might prove a useful screening tool for progression.