What is it? Why is it important?

An Adverse Event (AE) is any untoward medical occurrence in a participant administered an Investigational Medicinal Product (IMP), but which does not necessarily have a causal relationship with the treatment.


AE is defined as:

  • An unfavourable and unintended sign (e.g. abnormal laboratory finding), or
  • A symptom or disease temporally associated with the use of an Investigational Medicinal Product (IMP)


In studies, the assessment of AEs is mandatory (e.g. based on HRA). Still, the extent of AE documentation and reporting depends on the risk category of the study.


As required, AE documentation and reporting starts and is mandatory once the participant has signed the ICF until:

  • Study termination (e.g. last study participant at last study visit), or
  • The end of some predefined safety follow-up period (e.g. as defined in the study protocol)

What do I need to do?

As a Site-INV and SP-INV:

  • Perform AE assessments. In the event of a serious event, proceed accordingly (e.g. SAE reporting)
  • If applicable, document AEs in a standardised manner (e.g. patient-file and eCRF). Include any medical care provided to participants
  • Follow reporting requirements as defined in the study protocol (e.g. reporting timelines from Site-INV to SP-INV, summary of all AEs in a study annual safety report and a clinical study report at study end)


During study conduct, the requirement of AE documentation depends on study risk:

  • Category A (low risk): has no documentation requirements except:
    • If required based on the study protocol
    • The study endpoint is the safety outcome of the study
  • Category B (medium risk): must document AEs based on:


Category C (high risk): must document all AEs

Where can I get help?

Your local CTU can support you with experienced staff regarding this topic


ICH GCP E2A – see in particular chapter

  • Chapter II Definition

ICH E6(R2) – see in particular guideline

  • 1.2 AE definition

Swiss Law

ClinO – see in particular article

  • Art. 39 Documentation of AE


  • AE – Adverse Event
  • BASEC - Business Administration System for Ethics Committees
  • ClinO – Clinical Trials Ordinance
  • CTU – Clinical Trials Unit
  • EC/RA – Ethics Committee / Regulatory Authorities
  • eCRF – electronic Case Report Form
  • HRA – Human Research Act
  • ICH GCP – International Council for Harmonisation - Good Clinical Practice
  • ICH – International Council for Harmonisation
  • ICF – Inform Consent Form
  • IMP – Investigational Medicinal Product
  • SAE – Serious Adverse Event
  • Site-INV – Site-Investigator
  • SP-INV – Sponsor-Investigator
Conduct ↦ Safety ↦ Medicinal Product Safety Reporting ↦ Adverse Event

Provides some background knowledge and basic definitions

Basic Monitoring
Basic Drug or Device

Starts with a study idea

Ends after having assessed and evaluated study feasibility

Concept Drug or Device

Starts with confidence that the study is feasible

Ends after having received ethics and regulatory approval

Development Drug or Device

Starts with ethics and regulatory approval

Ends after successful study initiation

Set-Up Ethics and Laws
Set-Up Quality and Risk
Set-Up Drug or Device

Starts with participant recruitment

Ends after the last participant has completed the last study visit

Conduct Drug or Device

Starts with last study visit completed

Ends after study publication and archiving

Completion Statistics
Completion Drug or Device
Current Path (click to copy): Conduct ↦ Safety ↦ Medicinal Product Safety Reporting ↦ Adverse Event

Please note: the Easy-GCS tool is currently under construction.