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

Objective: To assess safety of baricitinib in Japanese patients with rheumatoid arthritis in real-world clinical practice.

Methods: This all-case post-marketing surveillance study included patients initiating baricitinib for rheumatoid arthritis from September 2017 to April 2019. Treatment duration was recorded. Safety data were collected for up to 3 years from baricitinib initiation (up to 4 weeks post discontinuation 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 10.42/100 patient-years; 95% confidence interval, 9.76-11.09). There were 39 deaths (incidence rate 0.43 [0.30-0.57]/100 patient-years). Incidence rate per 100 patient-years for adverse events of special interest 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). Incidence rates did not increase with prolonged exposure.

Conclusions: No new safety concerns were identified during this 3 year post-marketing surveillance study of baricitinib in Japanese patients with rheumatoid arthritis. Patients and clinicians should be cognizant of herpes zoster and other serious infection risks during baricitinib treatment, especially in the first 6 months.