Ultrasound-detected joint inflammation and B cell count: related variables for rituximab-treated RA patients?

This cross-sectional observational study aimed to explore the relationship between B cell count and ultrasound (US)-detected synovitis, in patients with rheumatoid arthritis treated with rituximab. Thirty-seven consecutive RA patients treated with RTX were recruited for the study. The patients underwent clinical [i.e., Disease Activity Score 28 joints (DAS28)], laboratory, and US assessment of 12 joints. Each joint was semiquantitatively (0–3) scored on B-mode and power Doppler mode. The scores were summed, and a global index was created for BM (BMS) and PD scores (PDI) synovitis. BM subclinical synovitis was evident in all patients, with PD synovial signal detected in 16 patients (43.2 %). No correlation was found between DAS28 and US scores. B cells were detected in 27 (72.9 %) patients, but there was no association in the mean B cell count and disease activity as measured by DAS28 (DAS28 2.6 = 49.45, p = 0.52) and PDI score (PDI 1 = 35.44, p = 0.54). There was no correlation between the B cell count and DAS28, BMS, and PDI ( r = 0.020, p = 0.907; r = −0.151, p = 0.371; r = −0.099, p = 0.558, respectively). In RTX-treated RA patients, no relationship could be established between US-detected synovitis and peripheral blood B cell count.