Background Rituximab is a a chimeric anti-CD20 monoclonal antibody approved to reduce the signs and symptoms of moderately to severely active rheumatoid arthritis (RA) in patients with inadequate response to first line TNF inhibitors. Debating evidence regard the efficacy of rituximab on rheumatoid factor (RF) and anti-CCP antibodies dynamics in patients with active RA.

Objectives The aim of the study was to investigate possible correlations between the levels of serum RF and anti-CCP antibodies and disease activity in patients with established RA, assessed in a dual manner – using validated DAS28 with four variables and a simplified twelve-joint Power Doppler ultrasonographic assessment of joint inflammation after 24 weeks (first course)

Methods The study group consisted of 34 patients with established active RA (DAS28 >5.1) who failed at least one TNF inhibitor. All patients underwent standard clinical and biological evaluation, including RF and anti-CCP antibodies, with disease activity evaluation through DAS28 with four variables and using a twelve-joint simplified Power Doppler ultrasonographic assessment. PDUS was performed by the same rheumatologist, unaware of the clinical and laboratory findings, 24 synovial sites from 12 joints being investigated using a MyLab25 Gold scanner (Esaote, Italy), with a multifrequency linear array transducer (10-18MHz). Synovial fluid, synovial proliferation and power Doppler signal (hipervascularity) were scored semiquantitatively on a scale 0-3 in all sites prior to the rituximab infusion and after 24 weeks, before receiving a subsequent course

Results Patients studied had a high disease activity score expressed through a mean DAS 28 of 5.6 (± 1.6 SD), as well as increased mean values of RF and anti-CCP antibodies. 94.11% of patients were RF positive and 91.17% anti-CCP positive. After 24 weeks of treatment we observed a good response in 64.70% of patients according to EULAR and a moderate response in 35.29% of patients as well as a mean decrease from baseline in DAS28 significantly correlating with decrease in both RF (p<0.0001) and anti-CCP (p<0.001) titers. Significant decrease of RF (p=0.0001) and anti-CCP (p=0.001) antibodies was correlated with the decrease of the PDUS scores (for effusion, synovial hypertrophy, PD signal) after 24 weeks from the first course

Conclusions The study revealed the significant correlation between the decrease of the disease activity measured thorough DAS28 and PDUS scores for effusion, synovial proliferation and hipervascularity and the parallel decrease of the RF and anti-CCP titers after a first course of rituximab therapy in active rheumatoid arthritis

Disclosure of Interest None Declared