Comparison of the effects of baricitinib and tocilizumab on disease activity in patients with rheumatoid arthritis: a propensity score matching analysis

Objective This study aimed to compare the effects of baricitinib, a Janus kinase inhibitor, and tocilizumab, a monoclonal anti-interleukin-6 receptor antibody, on disease activity in patients with rheumatoid arthritis (RA), and to investigate the influence of inflammation on improvement in patient global assessment (PGA) of disease activity. Methods This study was performed based on data from a multicenter registry, and included 284 and 113 patients treated with tocilizumab and baricitinib, respectively, who were observed for longer than 24 weeks. Propensity score matching was performed to address potential treatment-selection bias. To assess the influence of inflammation on PGA, patients were divided into two groups based on whether or not they achieved improvement in C-reactive protein (CRP, an objective marker of inflammation) at 24 weeks. Results A total of 48 matched pairs of patients were identified. Compared to treatment with tocilizumab, baricitinib showed a similar improvement in tender and swollen joint count and serum CRP levels, and a significantly greater improvement in PGA at 24 weeks. As a result, the baricitinib group had a significantly higher proportion of patients who achieved Boolean remission at 24 weeks. In subgroups of patients who did not achieve 50% or 70% CRP improvement, significant decreases from baseline to 24 weeks were observed in PGA in patients treated with baricitinib, but not in those treated with tocilizumab. Conclusion Compared to tocilizumab, baricitinib significantly improved PGA despite similar effects on inflammation in patients with RA. Moreover, the influence of inflammation on PGA improvement differed between baricitinib and tocilizumab. Key-points • Baricitinib and tocilizumab had similar effects on inflammation in RA patients. • Baricitinib improved patient global assessment (PGA) more than tocilizumab. • Baricitinib had a higher Boolean remission rate than tocilizumab at 24 weeks. • Influence of inflammation on PGA improvement differed between the two drugs.