Informed consent.

Physicians have an ethical and legal duty to obtain patients' informed consent before ordering testing and treatment. Informed consent encompasses informed refusal, the correlative right of patients to refuse tests and therapies they do not want. A patient's informed consent requires adequate information, capacity to decide, and absence of coercion. Informed consent is incorporated into a process of agreement between a patient and a physician called "shared decision making." The procedural requirements of informed consent vary as a function of the risks of the tests or treatments. Incompetent patients require surrogate decision makers to consent or refuse on their behalf. Older children and adolescents should be asked to provide their assent for treatment in addition to their parents' permission. Treatment may be provided in an emergency situation without consent if the treatment given represents the standard of emergency care. Consent of human subjects for participation in research requires that they fully understand their role and risks, not be coerced, and be allowed to withdraw at any time without penalty. Institutional review boards help guarantee the protection of human subjects. Vulnerable research subjects, such as children and the cognitively or mentally impaired, require additional protection. Copyright 2001 John Wiley & Sons, Inc.