A SUSAR is a Suspected Unexpected Serious Adverse Reaction: serious adverse reactions in subjects given a drug, that may or may not be dose related, but are unexpected, as they are not consistent with current information. A SUSAR may occur during clinical trials or clinical care. Reporting is mandatory for clinical investigators in the EU. In the USA, reporting of adverse events during clinical trials is mandatory, but during clinical care, it is voluntary. The US FDA has a reporting system for Serious Adverse Events (SAEs) through the AERS (Adverse Event Reporting System). During the reporting process and assessment, it is decided if the adverse event was unexpected. In Canada, clinical trial sponsors are required to report SUSARs to Health Canada. The lack of harmonization between countries has been under assessment by the International Conference on Harmonization (ICH) for at least half a decade.
The definition for "Adverse Reaction" used by ICH is "Any untoward medical occurrence in a patient or clinical investigation subject administered a pharmaceutical product and which does not necessarily have to have a causal relationship with this treatment." An adverse reaction may be a response to non-active ingredients of a drug.
The following events consistute a "serious" adverse reaction, according to the EU:
Expert Working Group (Efficacy) of the International Conference on Harmonisation of Technical Requirements for Registration of Pharmaceuticals for Human Use (ICH). (August 25, 2007).