Data retention after a patient withdraws consent in clinical trials.

Patient retention is critically important in the conduct of a successful clinical trial. The power in numbers in multicenter trials is dependent on the completion of follow-up for every patient randomized. If at the end of a clinical trial, a significant number of randomized patients are missing outcome data, there will not be enough pool for data analyses to conclude a study based on its primary and secondary objectives. When patients who are either lost to follow-up or who withdraw consent during the clinical trial are eliminated from the data pool, they subsequently affect the power and the validity of conclusions derived from the clinical study. This paper aims to present current guidance on data retention for patients who have withdrawn consent from clinical trials.