Recent guidance released by the Food and Drug Administration (FDA) clarifies the agency's position on whether already-accrued data related to subjects who cease participating in a clinical trial or study are to be maintained as part of the study data. FDA regulations provide that when a subject withdraws from a study, the data collected on the subject to the point of withdrawal remain part of the study database and may not be removed. According to the FDA, "loss of these subjects' data could greatly distort effectiveness results and could hide important safety information (for example, toxicity) of a poorly tolerated treatment."

Key points outlined in the FDA guidance include the following: (1) an investigator may ask a subject who is withdrawing whether he or she wishes to provide continued follow-up and further data collection subsequent to withdrawal; (2) if a subject withdraws from the interventional portion of the study, but agrees to continued follow-up, the investigator must obtain the subject's informed consent for this purpose; (3) if a subject withdraws from the interventional portion of a study and does not consent to continued follow-up, the investigator may not access the subject's medical record for purposes related to the study. However, an investigator may review the subject's study data that were collected prior to withdrawal, and may consult public records related to the subject including those establishing survival status. A copy of the FDA guidance is available online.