Safety and research
SAE
Definition
A serious adverse event is an adverse event meeting defined outcome-based criteria such as death, life-threatening risk, hospitalisation, disability, or another medically important event.
Aliases and abbreviations
SAE · serious adverse experience
Editorial record
Published: August 25, 2026 · Reviewed: August 25, 2026
Expanded definition
Common seriousness criteria include death, a life-threatening event, inpatient hospitalisation or prolonged hospitalisation, persistent or significant disability, congenital anomaly, or another important medical event requiring intervention.
Seriousness is a regulatory and reporting classification based mainly on outcome or required action. Severity describes intensity, so a severe symptom may be non-serious while a moderate event may still meet serious criteria.
An SAE occurring during a trial is not automatically caused by the intervention. Causality, expectedness, and relationship are assessed separately, while expedited reporting rules may still apply.
What the term does not establish
Why the distinction matters
Accurate use of SAE prevents serious reporting obligations from being confused with ordinary severity scales and keeps causality claims separate.
Main guide
Research context for event classification, reporting quality, and protocol-specific safety interpretation.
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Measurement and interpretation
Editorial scope
This glossary entry supports general education. It does not diagnose, recommend treatment, or transfer findings from one VNS method, protocol, or device to another.