Once a patient has been randomized, changing the value of a stratification variable has no impact on the assigned treatment group.

Key points to understand

• The treatment group is assigned based on the stratification values at the time of randomization.
• Any change made after the randomization does not modify the group assignment.
• The patient’s allocation remains locked and is not recalculated.

What happens in the interface?

• If a stratification variable is edited after a patient has been randomized, a warning messageappears in the right-hand panel of the eCRF:

  “This value was used for randomization. Changing it will not affect the patient’s assigned group but may unbalance study strata.”

• This helps prevent accidental inconsistencies in stratification balance.

Can I edit stratification variables?

No, most properties of a stratification variable are not editable once you have configured your randomization protocol.

Beware of completely configuring your stratification variables before you configure your randomization.

Good practice

• Always double-check stratification fields before randomizing a patient.
• If you need to correct a mistake, log the reason and notify your data management team or sponsor, depending on your SOPs.