Implementation

Explanation

The process of randomising participants into a trial has three different steps: sequence generation, allocation concealment mechanism, and implementation. Investigators should strive for complete separation of the people involved with sequence generation and allocation concealment from the people involved in the implementation of assignments.

Failure to implement this separation may introduce bias. For example, the person who generated the allocation sequence will likely have access to a copy of the sequence list and may consult it if they were enrolling and assigning participants in a trial. Thus, that person could bias the enrolment or assignment process.

Authors of protocols should confirm complete separation of the people involved with sequence generation and allocation concealment from the people involved in the implementation of assignments and describe how this separation was achieved. If complete separation did not occur, then authors should describe how the people involved in the implementation will be prevented from accessing the allocation sequence (e.g., specifying that the allocation sequence will be locked in a secure location).

Reviews of two samples of 108 and 292 trial protocols from 2016 found that 73% and 56% respectively did not describe the persons who will enrol or assign participants.(9, 10)

Summary of key elements to address

● Who will have access to the random allocation sequence

● Who will enrol participants

● Who will assign participants to interventions

● Whether the personnel enrolling and assigning participants will have no access to the random allocation sequence

When individuals involved in sequence generation and allocation concealment are the same individuals involved in the implementation of assignment:

● How and where the random allocation list will be securely stored

● Any mechanisms to prevent those enrolling and assigning participants from accessing the list