Site-specific articular responses to b/tsDMARDs in rheumatoid arthritis: a longitudinal observational study from the...

Whether treatment response differs across affected joints in rheumatoid arthritis (RA) remains unclear. We sought to determine whether responses to tumour necrosis factor inhibitors (TNFi) and other biologic/targeted synthetic disease-modifying antirheumatic drugs (b/tsDMARDs) vary across individual joints in a large cohort of patients with RA.

Patients with RA from the Swiss Clinical Quality Management in Rheumatic Diseases registry with ≥1 swollen joint at treatment initiation of a b/tsDMARD (abatacept, interleukin-6 receptor inhibitor (IL-6Ri), Janus kinase inhibitor (JAKi), rituximab and TNFi) were included. Time to resolution of swollen joints was evaluated over a 2-year follow-up using mixed effects models accounting for interval-censored data. The analyses compared the speed of improvement of individual joints within the 28-joint count to that of the wrist. The primary analysis focused on bio-naïve patients initiating TNFi treatment, while secondary analyses included all b/tsDMARD classes, irrespective of treatment line.

A TNFi was initiated in 598 patients with ≥1 swollen joint, while 1942 patients with ≥1 swollen joint started a b/tsDMARD (abatacept: 242, IL-6Ri: 317, JAKi: 333, rituximab: 176, TNFi: 874). Compared with the wrist, all joints demonstrated higher rates of resolution, except for the second and third metacarpophalangeal (MCP2/3) joints and, in some analyses, the knee. This pattern of joint-specific response was consistent across all b/tsDMARDs.

The wrist, MCP2 and MCP3 joints resolve more slowly than other joints following treatment with b/tsDMARDs, indicating that a longer evaluation period of treatment response and/or bridging intra-articular steroid injections may be required when these joints are affected.