Safety of baricitinib in Japanese patients with rheumatoid arthritis in clinical use: 3-year data of all-case postmarketing surveillance study

Objectives To assess safety of baricitinib in Japanese patients with rheumatoid arthritis (RA) in real-world clinical practice.Methods This all-case postmarketing surveillance study included patients initiating baricitinib for RA from September 2017 to April 2019. Treatment duration was recorded. Safety data were collected for up to 3 years from initiation (up to 4 weeks postdiscontinuation in discontinuing patients).Results Safety analyses included 4720 patients; 2580 (54.7%) were >= 65 years old. Baricitinib persistence rate was 45.4% (3-year Kaplan-Meier analysis); the most common discontinuation reason was insufficient effectiveness (n = 1005, 21.3%). Serious adverse events occurred in 600 patients [incidence rate (IR) 10.42/100 patient-years (PY); 95% confidence interval, 9.76-11.09]. There were 39 deaths [IR 0.43 (0.30-0.57)/100 PY]. Adverse events of special interest IRs per 100 PY were herpes zoster 4.68 (4.22-5.14), serious infection 3.05 (2.68-3.41), malignancy 1.09 (0.87-1.30), major adverse cardiovascular events 0.35 (0.23-0.48), and venous thromboembolism 0.25 (0.15-0.36). IRs did not increase with prolonged exposure.Conclusions No new safety concerns were identified during this 3-year postmarketing surveillance study of baricitinib in Japanese patients with RA. Patients and clinicians should be cognizant of herpes zoster and other serious infection risks during baricitinib treatment, especially in the first 6 months.