They also help doctors identify who will benefit in the future from the approach being studied if it's shown to work. For example, in cancer prevention studies, a new drug may work for people with one type of risk factor but not for another. Eligibility criteria also help insure safety of participants by protecting them from known risks. For example, some drugs can only be given safely if a person has normal kidneys or liver. In this situation only persons with normal kidney or liver function are allowed to participate.
Clinical trials have several procedures to protect the safety of the people who participate.
One or more review groups have to approve the protocol for every study. Every study center has an IRB, which includes doctors, other health care providers, consumers, and sometimes members of the clergy. IRB members do not have any personal interest in the results of the study. They serve as neutral reviewers, ensuring that the study is conducted fairly and that no one who decides to become a participant is likely to be harmed. Each Phase III trial also has a special group called a Data Safety and Monitoring Committee that looks at the test results, monitors the safety of the participants, and decides whether the study should go forward as originally planned.