High frequency ultrasonography of the hand versus anti-RA33 evaluation in early rheumatoid arthritis - a pilot study

Accurate diagnosis and early treatment in rheumatoid arthritis (RA) can lead to a good outcome and a correct management of the disease. We aimed toinvestigate the prognostic value of anti-RA33 antibodies, by evaluating the relationship with ultrasonographic (US) findings in patients with early RA. We performed a prospective study which included 29 patients, diagnosed with early RA according to the ACR/EULAR 2010 criteria and 21 sex and age-matched control subjects. All patients underwent clinical and biological assessment, followed by US examination in grayscale (GS) and power Doppler (PD) at baseline and after 12 months [from the second to the fifth metacarpophalangeal (MCP) and proximal interphalangeal (PIP) joints and wrists (RCC), in dorsal aspect]. The second and fifth MCP joints were scanned also in lateral aspects. The initial GS evaluation revealed the presence of synovitis in all 29 patients; PD found at least one joint with a PD grade higher than 1 in 23 patients, higher than 2 in 20 patients, and grade 3 in 6 patients; at 12 months, we revealed the presence of GSUS synovitis in 25 patients and PDUS examination found active synovitis in 12 subjects. In those patients, the anti-RA33 titre was significantly lower compared to those without PDUS active synovitis (p=0.031), with a moderately negative correlation (r=-0.519, p=0.0039). The current study shows that anti-RA33 antibodies might constitute an additional tool for diagnosing early RA patients and can help identify patients with mild disease and a low level of activesynovitis.