UK Clinical Trial Adverse Event Reporting Requirements
Clinical trials are a fundamental component of medical product development, providing a controlled environment to evaluate the safety and performance of investigational medicinal products and medical devices prior to regulatory approval. These studies generate critical clinical data that support regulatory decision-making and ensure that new therapies meet established regulatory standards of safety and efficacy. Clinical trial safety reporting plays a critical role in ensuring regulatory compliance and protecting patient safety throughout the development lifecycle.
A central component of clinical trials is the identification, assessment, and reporting of adverse events. These events play a critical role in evaluating the safety profile of investigational products and informing benefit–risk assessments throughout development. Effective safety reporting ensures that emerging risks are identified early and that appropriate measures can be taken to protect patient safety. For more information, visit our articles section.
Safety reporting requirements are a key element of clinical trial regulation and require sponsors to establish structured procedures for the documentation, evaluation and communication of adverse events. These clinical trial safety reporting requirements form a critical component of regulatory compliance across both EU and international frameworks. This includes the reporting of serious adverse events (SAEs), suspected unexpected serious adverse reactions (SUSARs), and the preparation of periodic safety updates such as annual safety reports or development safety update reports (DSURs).
The following sections outline the adverse event reporting requirements in the United Kingdom, France, Germany and Switzerland, highlighting key regulatory authorities, reporting obligations, timelines and submission pathways.
Overview of Adverse Event Classification
Adverse events reported during clinical trials are typically categorized based on their severity, expectedness and relationship to the investigational product. Understanding these classifications is essential for determining reporting obligations and timelines.
- Adverse Event (AE): Any untoward medical occurrence in a participant, regardless of causal relationship.
- Serious Adverse Event (SAE): An event that results in death, is life-threatening, requires hospitalization, or causes significant disability.
- Suspected Unexpected Serious Adverse Reaction (SUSAR): AA serious adverse reaction that is unexpected based on existing safety information
These classifications guide regulatory reporting requirements, determine the urgency and scope of safety reporting obligations, and ensure that events with the greatest potential impact on patient safety are prioritized for rapid communication.
United Kingdom (MHRA)
Regulatory authority: Medicines and Healthcare products Regulatory Agency (MHRA)
Reporting requirements: All adverse events must be documented; serious adverse events (SAEs) must be reported promptly. Sponsors are responsible for evaluating safety data and ensuring compliance with reporting obligations throughout the clinical trial.
Reporting timelines:
- SAEs: within 24 hours to sponsor
- SUSARs: within defined regulatory timelines
Submission pathways:
- Sponsor
- National competent authority (MHRA)
- Ethics committees (as applicable)
France (ANSM)
Regulatory authority: Agence Nationale de Sécurité du Médicament et des Produits de Santé (ANSM)
Reporting requirements: Investigators must document all adverse events throughout the clinical trial. Sponsors are responsible for assessing causality and reporting SUSARs. Continuous safety evaluation is required to maintain an up-to-date benefit–risk assessment.
Reporting timelines:
- SAEs: within 24 hours to the sponsor
- Fatal or life-threatening SUSARs: within 7 calendar days
- Non-fatal SUSARs: within 15 calendar days
Submission pathways:
- Sponsor
- European safety database (e.g. EudraVigilance)
- National competent authority (ANSM)
- Annual safety reports submitted to ANSM
Germany (BfArM)
Regulatory authority: Federal Institute for Drugs and Medical Devices (BfArM)
Reporting requirements: Investigators must document and report adverse events, with particular attention to serious and clinically significant events. Sponsors are responsible for causality assessment and ensuring that all reportable events are communicated in accordance with regulatory requirements.
Reporting timelines:
- Life-threatening or fatal events: within 2 calendar days of awareness
- Other serious adverse reactions: within 7 calendar days
- Follow-up information: submitted as available
Submission pathways:
- National competent authority (BfArM)
- Ethics committees
- Inclusion in periodic safety reports
Key Classification Documents:
MDCG 2021-24: Guidance on
classification of medical devices MDCG 2022-5: Guidance on borderline
products MDCG 2019-11: Guidance on
qualification and classification of software
Switzerland (Swissmedic)
Regulatory authority: Swissmedic (Swiss Agency for Therapeutic Products)
Reporting requirements: All adverse events must be reported to the sponsor, regardless of confirmed causality. Sponsors must ensure ongoing safety monitoring, including identification and reporting of SUSARs, supported by formal written procedures.
Reporting timelines:
- SAEs: within 24 hours to the sponsor
- SUSARs: within defined regulatory timelines
Submission pathways:
- Sponsor
- Swissmedic
- Inclusion in annual safety reports or DSURs
Key Classification Documents:
MDCG 2021-24: Guidance on
classification of medical devices MDCG 2022-5: Guidance on borderline
products MDCG 2019-11: Guidance on
qualification and classification of software
Summary of Adverse Event Reporting Requirements
| Country | Authority | Timeline | Reporting To |
|---|---|---|---|
| France | ANSM | Within 24 hours | Sponsor, EU database |
| Germany | BfArM | 2 days (serious cases) | National Authority |
| Switzerland | Swissmedic | Within 24 hours | Sponsor, Swissmedic |
EUDAMED Safety Reporting Requirements
The European Database on Medical Devices (EUDAMED) is a centralized information system developed by the European Union to improve transparency, coordination and accessibility of information related to medical devices . It is intended to serve as a central platform for the submission and exchange of regulatory data, including safety information and post-market surveillance data.
Once fully implemented, EUDAMED is expected to streamline safety reporting processes across EU Member States by enabling centralized submission of data and improved communication between manufacturers, regulators and other stakeholders. This will support more efficient identification of safety signals and enhance regulatory oversight.
However, as EUDAMED continues to be developed and implemented in stages, manufacturers must currently comply with existing national reporting requirements and EU regulatory frameworks.
Factors Influencing Variability in Adverse Event Reporting
These factors should be considered when interpreting adverse event data and assessing the overall benefit–risk profile of an investigational product.
For additional reading and regulatory guidance:
Conclusion
Adherence to adverse event reporting requirements is essential for maintaining regulatory compliance and ensuring patient safety. By implementing structured and timely reporting processes, manufacturers and sponsors can support accurate benefit–risk assessments, enhance the safety and performance of medical products and support the continuous improvement of clinical practice and patient outcomes.
