Response to Xing et al.: post-marketing safety concerns with Lecanemab: a pharmacovigilance study based on the FDA adverse event reporting system database.

A recent paper published a lecanemab analysis with data from the United States Food and Drug Administration (FDA) Adverse Event Reporting System (FAERS) database. While the authors mention the limitations of FAERS, such as "voluntary (underreporting), the inability to establish causality, reporting bias, data quality issues, and the absence of a denominator, which precludes calculating incidence rates", they proceed with generalizations, clinical conclusions, and even treatment recommendations based on the crude disproportionality analysis. Consideration of post-marketing safety reports, including those found in the FAERS database, is an essential component of pharmacovigilance. However, FDA guidance [2, 3] highlights that: (1) "Rates of occurrence cannot be established with reports," (2) "Documenting one or more of these outcomes in a report does not necessarily mean that the suspect product(s) named in the report was the cause of the outcomes," and (3) "Importantly, the FAERS data by themselves are not an indicator of the safety profile of the drug." The FAERS database includes reports from many sources, including reports by companies, as well as from health care professionals and consumers. The reports in the FDA database have significant limitations, including submission of incomplete, inaccurate, untimely, duplicate, relatedness to drug uncertainty, and/or unverified information. Therefore, broader generalizations, clinical conclusions, and treatment recommendations should not be made based solely on FAERS databases analyses.