Which of the following is true about AE causality assessment?

• A. It is determined by the investigator.
• B. It is determined by the sponsor.
• C. It is determined by the ethics committee.
• D. It is determined by the data monitoring committee.

Answer: (A)

The investigator determines AE causality because they are closest to the patient and have the full context of the event, including timing, the patient’s response to stopping or reintroducing the study drug, and alternative explanations. In practice, the investigator assesses whether an adverse event is related to the investigational product using factors like temporal relationship, dose-response, dechallenge/rechallenge, and ruling out other causes. This judgment is documented in the safety reports that are then shared with sponsors and oversight bodies.

The sponsor plays a key role in collecting safety data and reporting to regulators, but the formal causality assessment for individual AEs is not their responsibility. The ethics committee (or IRB/IEC) focuses on ongoing risk-benefit and participant protection rather than making causal determinations for each event. The data monitoring committee reviews safety trends and can recommend actions based on safety signals, but they do not assign causality for each AE.