Unblinding is the process of disclosing treatment allocation in a blinded clinical trial. This is a strictly controlled procedure that takes place only under specific circumstances. A distinction is made between planned unblinding at the end of the trial and unplanned or emergency unblinding during the trial.
Planned unblinding takes place after database lock, once all data have been captured and cleaned, in order to perform the final statistical analysis. Emergency unblinding for an individual patient may become necessary if a serious medical event occurs and knowledge of the treatment is critical for the patient’s ongoing care. This process must be carefully documented. Premature or improper unblinding can jeopardize the integrity of the entire trial. CROs therefore implement robust procedures and systems (e.g., via IWRS) to protect blinding and to enable controlled emergency unblinding.