The beneficial effect of baricitinib on ultrasound-detected synovial inflammation and bone damage in rheumatoid arthritis: Preliminarily data from single center-based observational study for 24 weeks

Baricitinib is a Janus kinase (JAK) inhibitor that selectively blocks against JAK1 and JAK2 signaling. This study aimed to determine the effect of baricitinib on disease activity based on musculoskeletal ultrasound in patients with rheumatoid arthritis (RA). A total of 20 patients with RA receiving baricitinib for 24 weeks were assessed. Ultrasound scores of gray scale and power Doppler synovitis, joint effusion, and bone erosion in each patient were assessed between baseline and 24 weeks for 27 affected joints. Disease activity in RA was evaluated using the disease activity score for 28-joint count with erythrocyte sediment rate (DAS28-ESR), simplified disease activity index (SDAI), and clinical disease activity index (CDAI). Treatment with baricitinib for 12 weeks and 24 weeks significantly decreased disease activity composites such as DAS28-ESR, SDAI, and CDAI (P < .001 for all). Treatment with baricitinib for 24 weeks improved ultrasound-detected gray-scale and power Doppler synovitis and joint effusion compared to baseline (P = .002, P = .030, and P = .002, respectively). Bone erosion scores were not different between baseline and 24 weeks (P = .317). There were no differences in ultrasound abnormalities for improvement based on DAS28-ESR. Changes in power Doppler score were significantly associated with changes in DAS28-ESR (β = 0.590, P = .044), but not SDAI and CDAI. This study demonstrates that baricitinib treatment has a favorable effect on ultrasound-detected abnormalities including synovitis and bone erosion in patients with RA.