When evaluating the causality of an adverse event, it is important to consider the temporal relationship of the event to the drug administration, the evidence of a dechallenge and rechallenge, the association of the event with other clinical or laboratory findings, and the plausibility of the event being caused by the drug. This is because temporal relationship, dechallenge/rechallenge, and association with other findings can all be indicators of causality. Additionally, the plausibility of the event being caused by the drug gives credibility to the assessment.
The temporal relationship of the event to the drug administration helps determine whether the drug caused the event, since if the event occurred shortly after the drug was administered it is more likely to be a result of the drug than if the event occurred several days or weeks later. Dechallenge and rechallenge can also help determine causality, as if the event goes away when the drug is discontinued and returns when it is resumed, it is highly likely to be a result of the drug. Similarly, if the event is associated with other clinical or laboratory findings it is more likely to be caused by a drug than if it is not. Finally, the plausibility of the event being caused by the drug can help assess causality, as if the event is listed as a known side effect of the drug it is more likely to be caused by the drug than if it is not.
In summary, when evaluating the causality of an adverse event, it is important to consider the temporal relationship of the event to the drug administration, the evidence of a dechallenge and rechallenge, the association of the event with other clinical or laboratory findings, and the plausibility of the event being caused by the drug. By taking all of these factors into account, it is much easier to accurately evaluate causality.