Reporting of adverse events in drug trials (AE, SAE and SUSAR)

– what the abbreviations mean and what reporting obligations and deadlines exist –

During a clinical trial, it is crucial to record, report and assess side effects to ensure the patients’ safety. The difference between an adverse event (AE) and a serious adverse event (SAE), and the concept of SUSARs (suspected unexpected serious adverse reactions) will be briefly outlined below:

Adverse events

Every symptom, every disease and every adverse event (including a runny nose during the cold season and abnormal laboratory values) that a patient experiences after administration of a study drug is classified as an adverse event (AE). In this context, it makes no difference whether a causal relationship with the treatment is suspected or whether the event is completely unrelated to the study drug. The investigator (study doctor) assesses the severity of an adverse event. Non-serious AEs are recorded in the source data (patient file) and in the CRF (case report form for clinical trials) by the investigator within the deadlines stipulated in the protocol. The physician documents the symptoms, the severity, the start / end, any countermeasures taken and the causality assessment. Serious adverse events, on the other hand, are subject to special reporting obligations and deadlines.

Serious adverse events

A serious adverse event (SAE) is any untoward occurrence that at any dose is fatal or life-threatening, requires inpatient treatment or a prolongation thereof, leads to persistent or significant disability or incapacity, or results in a congenital anomaly or a birth defect. Examples of an SAE include, for example, a heart attack or prolonged hospitalisation due to elevated liver values. Unless the report can be waived based on stipulations in the protocol, the Investigator’s Brochure or the Summary of Product Characteristics, the investigator reports the SAE to the sponsor immediately (within 24 hours after he/she becomes aware of it). If the investigator does not have all the information at this point in time, the missing information has to be submitted as soon as it becomes available.


The investigator assesses whether a causal relationship between the observed SAE and the use of the study drug is probable. If a causal relationship is considered to be at least possible, and if the event is a previously unknown reaction, it is referred to as a suspected unexpected serious adverse reaction (SUSAR). Reactions whose nature or severity are not in line with the known data about the safety and tolerability of a product (from the Investigator’s Brochure or Summary of Product Characteristics) are referred to as “unexpected”. A SUSAR is thus an adverse event that is both unexpected and serious and that is suspected of having a causal relationship with the study drug and could thus classify as a side effect. SUSARs are subject to immediate reporting. The sponsor notifies the investigator, the competent federal higher authority, the lead ethics committee and the competent authorities of other member states immediately, but at the latest within 15 days after he/she becomes aware of the SUSAR. This deadline is shortened to 7 days if an unexpected adverse event is life-threatening or resulted in death.


The pharmacovigilance department of MEDICRO takes care of all reporting obligations in your trial in a timely manner. Find out more in a personal conversation.