# Comparative safety profiles of baricitinib and tofacitinib in the treatment of adult alopecia areata: a pharmacovigilance study based on the FAERS database

## TL;DR

This study compares the safety of baricitinib and tofacitinib for treating adult alopecia areata using FDA adverse event reports, finding distinct safety patterns influenced by drug approval and usage.

## Contribution

The study identifies drug-specific safety signals in real-world alopecia areata treatment using FAERS data, highlighting differences in adverse event reporting.

## Key findings

- Baricitinib reports showed higher proportions of serious adverse events compared to tofacitinib.
- Baricitinib was associated with signals in infections and laboratory investigations, while tofacitinib showed signals in injury and medication-related issues.
- Safety signals varied by age and gender subgroups for both drugs.

## Abstract

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.

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.

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.

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.