There are five main levels of adverse events to be aware of when running any research study at North Bristol NHS Trust.

• Adverse Events (AEs) are any unfavourable and unintended signs, including abnormal laboratory results, symptoms or a disease associated with treatment. These must always be recorded on a Case Report Form (CRF) and in the patient's medical notes unless the protocol states otherwise.
• Adverse Reactions (ARs) are adverse events but causally related to investigational medicinal products.
• Serious Adverse Events (SAEs) are defined as any untoward medical occurrence(s) that at any dose results in death, hospitalisation or prolongation of existing hospitalisation, persistent or significant disability/incapacity or a congenital anomaly or birth defect. These events must be reported immediately to the sponsor. 
• Suspected Serious Adverse reactions (SSARs) are any ARs considered consistent with information available about an Investigational medicinal Product (IMP). They must be reviewed at regular intervals to see if the profile of any IMP has changed and a record made of this.
• Suspected Unexpected Serious Adverse Reactions (SUSARs) are any events suspected to be caused by an IMP, but which are not consistent with information about the IMP (these are the most serious of events and are subject to expedited reporting procedures).