What is the difference between a screen failure and a participant who withdrew early?

Generally, a screen failure is someone who does not get enrolled into the study for various reasons, documented during the screening process. Screen failures signed the consent form and may have had screening procedures but did not undergo any other study procedure. Reasons for the participant to fail screening may include, but are not limited to, the participant not meeting inclusion criteria or meeting exclusion criteria (ineligibility). Your sponsor or protocol may define a screen failure differently.

A “participant who withdrew” is a participant who either:

1)  stopped the study before completing the full schedule of study visits (including follow-up),
– OR –
2) who transferred sites.

Some protocols may have a variable number of visits and consider participants as completing, rather than withdrawing, in the case of disease progression or similar clinical outcome. In such cases, the protocol definition should be followed, with the withdrawal category reserved for participants who withdrew for other reasons.