I am having difficulty finding guid

I am having difficulty finding guidance about pre-existing events and reporting of adverse events. Over the last 10 years in research it has been my understanding that a pre-existing condition (any condition that existed prior to the first drug/vaccine administration) is not an adverse event unless the condition increases in severity, frequency or changes in character from baseline (e.g., change from Grade 1 to Grade 2 severity/ requires more potent medication, when there is a noticeably increased frequency of episodes, or if the condition’s characteristics / manifestations differ from what was previously experienced (headaches change how they manifest-instead start in front of the head and have a mild throb opposed to previous general overall ache) after the subject begins study investigational product.