The Ontology of Adverse Events in 2025

The Ontology of Adverse Events (OAE) was launched in 2011 to define, standardize and integrate various adverse events (AEs) arising after medical interventions. The terminological framework of OAE has undergone consistent expansion since its inception, driven by its successful implementation in numerous AE investigations. In this paper, we document substantial ontological extensions addressing patient anatomic regions and clinical manifestations, encompassing symptoms, physical signs, and pathological processes. Current statistical analysis reveals that OAE has 10,829 formally defined terms with unique identifiers. Compared to the 3,088 ontology terms included in the last OAE publication in 2014, 7,741 new terms have been added to OAE, which represents significant progress of the ontology in clinical granularity and domain coverage. The OAE framework enables structured representation of critical determinants influencing clinical outcomes, including but not limited to administration routes, dosage parameters, and demographic variables such as patient age. Through its standardized semantic architecture, OAE provides an integrative platform for cross-disciplinary analysis of AE patterns, etiological factors, and outcome trajectories in clinical interventions.