Baricitinib, a JAK1/JAK2 inhibitor, is already used to treat rheumatoid arthritis and other immune diseases. Clinical trials have demonstrated its effectiveness, but long-term use may lead to adverse drug reactions (ADRs) such as infections, thrombosis, and liver dysfunction. Real-world safety studies of baricitinib are limited. This study aims to evaluate the safety of baricitinib using the FDA Adverse Event Reporting System (FAERS) database.

This study adopted baricitinib-related report data from the FAERS database for the period from the third quarter of 2017 to the fourth quarter of 2023. Data cleaning and screening were conducted using the OpenVigil 2.1 platform, excluding duplicate and irrelevant reports. Signal detection was performed using four statistical methods, including Reporting Odds Ratio (ROR) and Proportional Reporting Ratio (PRR)(hereinafter referred to as ROR and PRR), to analyze the potential risks of baricitinib-related ADRs. Descriptive statistical analyses were also conducted.

From 2017 to 2023, a total of 47 776 724 adverse event reports related to baricitinib were received, and after data cleaning, 9 592 793 reports were included in the final analysis. Among these reports, female patients accounted for 61.4%, and most reports originated from the United States (45.4%). The main adverse reactions included pulmonary embolism, deep vein thrombosis, herpes zoster, and mitral valve perforation, with some signals (e.g., interstitial lung disease, ischemic stroke) not mentioned in the drug package insert. Baricitinib-related ADRs primarily involved infections, respiratory, nervous, and cardiovascular systems.

Through the latest database, this study reflects the real-world safety data of baricitinib over a longer time period. The research found that the main adverse reactions of baricitinib include infections, pulmonary embolism, and herpes zoster, and for the first time identified previously unreported risk signals, such as interstitial pneumonia and atrial fibrillation. This study provides updated evidence for both the academic community and clinical practice, offering guidance for patient management in future clinical applications. In clinical practice, special attention should be paid to the safety of elderly patients and high-risk groups to ensure rational use.