Adverse event (AE)
In Safety & pharmacovigilance
An adverse event is any unfavorable medical occurrence in a participant during a trial, whether or not it is thought to be caused by the study treatment. It can be a new symptom, an abnormal test result judged clinically significant, or the worsening of an existing condition. The key point is that no causal link is implied by the term itself.
Why it matters
Recognizing that an adverse event does not mean the drug caused it is the single most common misunderstanding among people new to clinical research \u2014 and it comes up in interviews.
Example
A participant twists an ankle playing football during the study. It is an adverse event even though nobody thinks the study drug caused it.
Common questions
- What is the difference between an adverse event and an adverse reaction?
- An adverse event is any unwanted medical occurrence, related or not. An adverse reaction is an adverse event for which there is at least a reasonable possibility that the study treatment caused it.
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