Comparative Safety Profiles of Baricitinib and Tofacitinib in the Treatment of Adult Alopecia Areata: A Pharmacovigilance Study Based on the FAERS Database

Lingsong Kong¹Xu Liu²Yanhuan Feng^3*

• ¹Department of Operation and Logistics Management, West China Tianfu Hospital, Sichuan University, Chengdu, Sichuan 610041, P. R. China., ChengDu, China
• ²Department of Dermatology, West China Hospital, Sichuan University, Chengdu, People’s Republic of China, ChengDu, China
• ³Department of Nephrology, Institute of Kidney Diseases, West China Hospital of Sichuan University, Chengdu 610041, China, ChengDu, China

Objective: To provide a comparative overview of the post-marketing safety patterns of baricitinib and tofacitinib used for the treatment of adult alopecia areata (AA) by analyzing spontaneous reports from the FDA Adverse Event Reporting System (FAERS). Given the different regulatory approval statuses and real-world usage contexts of the two drugs, this study aims to identify potential safety signals rather than to estimate incidence or establish causal associations. Methods: FAERS data from 2004Q1 to 2024Q1 were retrieved and systematically cleaned using FDA-recommended deduplication procedures. Reports involving baricitinib or tofacitinib with adult AA as the indication were included. Adverse events were standardized using MedDRA (v27.0). Disproportionality analyses were conducted using ROR, PRR, BCPNN, and MGPS. Subgroup analyses were performed by age, gender, and report severity. Statistical comparisons of categorical variables were conducted using χ² or Fisher's exact tests where appropriate. As FAERS lacks drug-exposure denominators, the results reflect reporting disproportionality rather than comparative risk. Results: A total of 550 baricitinib reports (941 events) and 648 tofacitinib reports (1927 events) were identified. The proportion of reports classified as serious was higher for baricitinib than for tofacitinib (P<0.05), although this may be influenced by differences in approval status, reporting patterns, and market duration. For baricitinib, disproportionality signals were mainly observed in infections, general disorders, and laboratory investigations. For tofacitinib, signals were primarily related to injury, poisoning, and medication-related issues, consistent with its off-label use for AA. Subgroup analyses suggested variations in signal patterns across gender and age groups. No causal relationships can be inferred from these findings. Conclusion: Baricitinib and tofacitinib exhibit distinct post-marketing safety signal patterns when used in adult AA, likely influenced by their different regulatory indications and real-world utilization contexts. These pharmacovigilance results should be interpreted as hypothesis-generating and may help guide clinical vigilance and future analytical studies. Prospective research with controlled exposure data is needed to validate the safety signals identified in FAERS.