Which statement best describes subject exclusion criteria?

• A. The medical conditions that would qualify a subject
• B. The inclusion criteria used to select eligible subjects
• C. The exclusion criteria that would disqualify subjects
• D. The schedule for follow-up visits after enrollment

Answer: (C)

Exclusion criteria are the factors that would disqualify someone from participating in a study. They’re defined before screening to protect participant safety and to ensure the data are interpretable and the trial can be conducted as planned. These criteria specify medical conditions, treatments, or other factors that would make enrollment inappropriate or unsafe—such as active infection, certain drug interactions, pregnancy, or an inability to comply with the protocol. This is different from inclusion criteria, which describe the characteristics a person must have to be eligible. The follow-up visit schedule, while part of the protocol, concerns when assessments occur after enrollment, not whether a person is eligible to join.