Adverse event

An adverse event refers to an unfavorable medical occurrence in a clinical trial subject who has been administered a pharmaceutical substance, whether or not it is considered drug related. An adverse event may be a physical event (sign, symptom), a psychological event (eg: change in mood), a laboratory event, or an increase in the severity or frequency of a preexisting symptom or condition.

Adverse events can be further classified as:

  • Life threatening adverse events- occurrence places subject at immediate risk of death.
  • Serious adverse events-occurrence leads to any of the following
    • Death.
    • Life-threatening adverse effect.
    • Inpatient hospitalization or prolongation of existing hospitalization.
    • Persistent or significant disability or incapacity.
    • Birth defect.
    • Requires medical intervention to prevent any of the above.
  • Suspected adverse events- adverse events for which there is a reasonable possibility that the drug caused the event and there may be evidence to suggest a causal relationship.
  • Unexpected adverse events- adverse events that are not listed under known risks in the investigator’s brochure or drug’s current labeling, or adverse events that are more severe or more specific than indicated. 

Source: Investigational New Drug Application, 21 C.F.R. § 312.32 (2010).