definiens: means any untoward medical occurrence that at any dose : results in death ; is life - threatening ( defined as an event in which the subje ct or patient was at risk of death at the time of t he event ; it does not refer to an event which hypothetically mig ht have caused death if it were more severe ) ; requi res inpatient hospitalization or causes prolongation of existing hospitalizations ; results in persistent o r significant disability / incapacity ; results in a congenital anom aly / birth defect ; is an important medical event ( de fined as a medical event(s ) that may not be immediately life - t hreatening or result in death or hospitalization, b ut based upon appropriate medical and scientific judgment, m ay jeopardize the patient / subject or may require intervention, e.g., medical surgical, to prevent on e of the other serious outcomes listed in the defin ition above )