SUSARs | Suspected Unexpected Serious Adverse Reactions

Suspected Unexpected Serious Adverse Reactions

Suspected Unexpected Serious Adverse Reactions (SUSARs) are serious, unexpected adverse events suspected to be related to a drug during a clinical trial. Prompt reporting to authorities and ethics committees is mandatory.

Managing SUSARs helps protect participants and may lead to protocol or dosage adjustments for the investigational medicine.

A SUSAR (Suspected Unexpected Serious Adverse Reaction) is a safety event occurring during a clinical trial that meets four criteria:

• Suspected: It is reasonably believed to be related to the investigational medicinal product (IMP).
• Unexpected: The nature or severity is not consistent with the product information (e.g., Investigator’s Brochure or SmPC).
• Serious: It results in death, is life-threatening, requires or prolongs hospitalisation, leads to significant disability, or is a congenital anomaly.
• Adverse Reaction: There is a suspected causal relationship with the IMP.

SUSARs require expedited reporting to regulators, ethics committees, and investigators.

SUSARs are critical safety signals. Because they are both serious and unexpected, they may reveal new risks about the investigational product and require immediate regulatory oversight.

Timely reporting protects participants and enables regulators to assess whether protocol amendments, risk-mitigation measures, or trial suspension are needed.

• A life-threatening arrhythmia in a trial participant when this risk is not described in the Investigator’s Brochure
• A severe hypersensitivity reaction occurring at a frequency or intensity greater than expected
• A congenital anomaly not previously associated with the IMP

These events exceed what is known about the product at the time of reporting.

Regulatory timelines differ depending on severity:

• Fatal or life-threatening SUSARs: must be reported within 7 days, with follow-up information within 8 additional days.
• All other SUSARs: must be reported within 15 days.

Reporting obligations apply under both the EU Clinical Trials Directive and the EU Clinical Trials Regulation (CTR 536/2014).

In the EU, SUSARs are submitted through EudraVigilance.

The sponsor of the clinical trial holds primary responsibility. This includes:

• Assessing causality
• Determining whether the event is expected or unexpected
• Reporting within regulatory timelines
• Notifying all investigators participating in the trial

Investigators must promptly document and communicate any serious adverse events (SAEs) to the sponsor.