All clinical trials have rules about who can and cannot participate. These rules are called “eligibility criteria.” The criteria are based on factors such as age, gender, the type and stage of a disease, previous treatment history, and other medical conditions. Eligibility criteria is not used to reject people personally. Instead, the eligibility criteria helps to make sure that the participants in the trial are safe and that the trial gets the most accurate information about the treatments being researched.
Some clinical trials seek participants with certain illnesses or conditions, while others need healthy participants.