Why is the “Randomize” button disabled / not visible for a patient?

The “Randomize” button may appear disabled (greyed out) in the eCRF for several reasons. This is usually to ensure protocol compliance or to preserve blinding.

Here are the most common causes:

1. The patient has already been randomized

• A patient can only be randomized once.
• Once assigned to a group, the button disappears and the allocation is locked.

2. You do not have the “Can randomize” permission

• Only users with the specific randomization permission can trigger the allocation.
• Ask a study administrator to verify your permissions.

3. Not all required fields are filled

• If the study uses stratified or minimization randomization, all related variables (e.g. center, sex) must be filled in the eCRF.
• If any of these fields are missing, the button will remain disabled.

4. The randomization variable is not visible

• If the randomization variable is hidden due to a display condition or restricted sharing (category access), you won't be able to randomize the patient.
• In that case, a tooltip appears next to the "Randomize" section in the left menu of the patient form:

  “Randomization is not available for this patient because the randomization field is currently hidden.”

5. The randomization configuration is invalid

• If the configuration has been deleted or corrupted, randomization is temporarily unavailable.
• This is rare and typically resolved by the study administrator.