How are trial participants selected?
Investigators develop a set of eligibility criteria for selecting clinical trial participants. These criteria are used to ensure that the treatment is appropriate and safe for participants. For example, researchers may choose to investigate the effect of a drug on female stroke patients without a history of other illnesses, rather than on stroke patients with other complications. In some cases, researchers need to restrict participation in a clinical trial to protect patients from known risks. For example, some drugs can only be given to patients with healthy kidneys; patients with kidney disease would therefore not meet the eligibility criteria for clinical trials involving those drugs.
