What should subjects be informed about regarding their withdrawal from a study?

Subjects should be informed that they can withdraw from a study at any time without any consequences. This principle is fundamental to ethical research practices and is emphasized in Good Clinical Practice (GCP) guidelines. It ensures that participants retain their autonomy and that their participation is based on informed consent. The right to withdraw is an essential component of the ethical principle of respect for persons, which acknowledges the agency of individuals in deciding whether or not to continue in a study.

This assurance allows participants to feel secure in their decision to partake in research, knowing they can stop their involvement whenever they choose, regardless of the circumstances. It's important for researchers to communicate this information clearly during the consent process, as it reinforces trust and transparency.

The other options do not align with these ethical standards. For instance, requiring participants to provide a reason or deliver their withdrawal in writing contradicts the principle of autonomy, as it places unnecessary constraints on their ability to withdraw freely. Furthermore, suggesting that participants cannot withdraw once they have signed the consent form directly opposes the foundational ethical guidelines governing human subjects research.