Multiple sclerosis as an adverse drug reaction: clues from the FDA Adverse Event Reporting System

Background: Possible relationship between drug exposure and multiple sclerosis (MS) development is insufficiently investigated, and further challenged by the incomplete understanding of MS etiopathogenesis. The study aims to investigate whether drug exposure could contribute to MS, by analyzing worldwide spontaneous reporting archives of adverse drug reaction (ADRs). Research design and methods: We retrieved information from the US Food and Drug Administration Adverse Event Reporting System (FAERS) over a 13-year period. Reporting odds ratio (ROR) for MS was calculated for each single substance. Disproportionality signals were considered when at least 10 cases were retrieved with a lower limit of the 95% confidence interval (CI) >1. Results: After a customized data-mining process, 3,226 reports of MS were retrieved. ‘Antineoplastic and immunomodulating drugs’ (33% of total reports) were the most frequently reported, with 10 disproportionality signals, including etanercept (445 cases; ROR: 2.48; 95% Cl: 2.24–2.74), adalimumab (329; 2.05; 1.83–2.30), and infliximab (119; 2.25; 1.87–2.70). We also observed signals for drugs acting on hormone balance, bone density, and central nervous system. Conclusion: Our findings suggest that immunomodulatory drugs increase the risk of MS and point out that some other drug classes should be further investigated for this risk.