Prevention. How much harm? How much benefit? 4. The ethics of informed consent for preventive screening programs.

Preventive interventions may have few or unproven benefits, or they may even be harmful. Since three of the fundamental precepts of Western biomedical ethics are beneficence, non-maleficence and respect for individual autonomy, failure to obtain truly informed consent for many current preventive interventions may be unethical. However, there are many impediments to obtaining such consent. Physicians need to be aware of an immense amount of up-to-date, complex information. It may be difficult for patients to assimilate this information, and there is rarely time for physicians to become informed and to inform their patients. Clinical practice guidelines may be helpful, but not all are based on evidence, and recommendations are often conflicting. Medical institutions, as well as individual clinicians, can help solve these dilemmas. Authors and journal editors can make a commitment to report and publish well-referenced evidence-based guidelines. Organizations such as the Canadian Task Force on the Periodic Health Examination and the US Preventive Services Task Force can develop balanced, evidence-based patient-information material. Faculty at all levels of medical education can increase their emphasis on the ethics of prevention. Individual clinicians should avoid making clinical decisions on the basis of relative reductions of morbidity or mortality, should use evidence-based clinical practice guidelines rather than those based on authority whenever possible, should make use of patient-information material and, most important, should have a consistent policy of obtaining informed consent from patients before they participate in potentially harmful preventive programs.