Age-Related Time-to-Onset Analysis of Drug-Associated Erythema Multiforme Using the Japanese Adverse Drug Event Report Database.

INTRODUCTION: Erythema multiforme (EM) is a rare immune-mediated skin condition often triggered by infections, drugs, or autoimmune diseases. Age-related differences in drug exposure, comorbidities, and biological factors may affect adverse event reporting patterns; however, age-related patterns in EM onset remain unclear. This study investigated age-related patterns in reported time-to-onset of EM. METHODS: The observation period was defined as 1-180 days from the initiation of drug administration. Kendall's tau-b rank correlation analysis was used to evaluate the association between ordered age categories and reported time to onset. The Kaplan-Meier method with a log-rank test was used to compare EM onset profiles between two age groups (<60 and ≥60 years). RESULTS: A positive association was observed between age category and reported time-to-onset (Kendall's tau-b = 0.188, p < 0.001). The median time-to-onset was 10.0 days in both men and women, although the Kaplan-Meier curves differed significantly by sex (log-rank p = 0.012). The median time-to-onset was 8.0 (3.0-13.0) days for those aged <60 years and 12.0 (7.0-24.5) days for those aged ≥60 years (log-rank p < 0.001). CONCLUSIONS: Older age was associated with longer reported time-to-onset of EM, suggesting age-related differences in reported EM onset patterns in a spontaneous reporting database.