Unblinding in the Add-Aspirin trial

Participants in the Add-Aspirin trial take either 100mg aspirin, 300mg aspirin or a matched placebo, once daily for approximately five years. Add-Aspirin is a double-blind trial. This means that neither the participant nor their doctors will know which treatment they have received.

Almost all clinical scenarios can be managed by assuming a trial participant is taking 300mg of aspirin once a day and withholding the trial medication. We only expect unblinding in the Add-Aspirin trial to be necessary in rare clinical circumstances where knowledge of treatment allocation is essential to guide clinical management. Guidance on a number of anticipated scenarios with specific advice about the need to unblind can be found here.

If unblinding is felt to be clinically essential, all NHS doctors are able find out a participant’s treatment allocation through the unblinding process. Where unblinding is being considered, wherever possible, the case should first be discussed with the MRC CTU or with the trial team at the recruiting hospital (named on the participant’s Add-Aspirin trial card). A flow diagram of the unblinding process can be found here.

To contact MRC CTU
Phone: +44 (0)20 7670 4892 (during normal working hours)
Email: mrcctu.add-aspirin@ucl.ac.uk

All NHS doctors can directly access treatment information in an emergency using the link below, and entering their GMC number and NHS email address in addition to the participant’s trial number and date of birth. The participant’s trial number can be found on their Add-Aspirin trial card. Unblinding details will be sent to the NHS email address provided.

UNBLINDING SHOULD ONLY BE PERFORMED BY AN NHS DOCTOR AND SHOULD
ONLY BE CONSIDERED WHERE KNOWLEDGE OF TREATMENT ALLOCATION
IS ESSENTIAL TO GUIDE CLINICAL MANAGEMENT

In the event that you are unable to contact the MRC CTU and you consider unblinding to be essential for the participant’s immediate management, please proceed to unblind the participant. MRC CTU should be contacted as soon as possible after unblinding.

Unblind a participant in the UK