Definition in SFDA (03/28/2008):
Adverse Drug Event (abbreviated as ADE) and Adverse Drug Reaction have different meanings. Generally speaking, an adverse drug reaction is a reaction for which the cause and effect relationship has been established, while an adverse drug event is a reaction for which the cause and effect relationship has not been established. It is often found in foreign drug inserts, and this reaction is not certain to be caused by the drug and needs further evaluation. The international definition of an adverse drug event is that it is an adverse clinical event that occurs during the course of drug therapy, and it does not necessarily have a causal relationship with the drug.
Definition in the Code of Practice for the Quality Management of Pharmaceutical Clinical Trials (Bureau Decree No. 3, September 1, 2003):
AdverseEvent, an undesirable medical event that occurs after a patient or clinical trial subject receives a pharmaceutical product, but is not necessarily causally related to the treatment.
Definition in ICH-GCP:
AdverseEvent (AE), any unfortunate medical event that occurs in a patient receiving a medication or in a clinical research subject that is not necessarily causally related to treatment. Thus, an adverse event (AE) can be any unfavorable and unintended sign (including abnormal laboratory findings), symptom, or disease temporally related to the use of an (investigational) medication, regardless of whether it is related to the medication.