What is an adverse event (AE)?

An adverse event (AE) is defined as any unintended sign, symptom, or medical condition that occurs in a participant during a clinical trial, regardless of whether it is considered related to the treatment being studied. This definition emphasizes that AEs are not limited to serious events but include any negative occurrences that affect a participant's health during the study. Identifying and reporting AEs is critical for evaluating the safety and tolerability of interventions in clinical research.

In the context of clinical trials, it is essential to distinguish AEs from planned outcomes or favorable effects, as such differentiations help ensure participant safety and data integrity. Adverse events, being unanticipated, necessitate thorough monitoring and reporting, which are pivotal parts of adhering to Good Clinical Practice (GCP) guidelines. Recognizing the nature of AEs allows researchers to work towards improving patient safety and making informed decisions regarding the study's course based on the data collected.