What makes placebo-controlled trials unethical?

This chapter examines the debate over the ethics of placebo-controlled trials. The ethical reasoning underlying a prohibition of placebo controls in randomized controlled trials when proven effective treatments exist has been presented most clearly and persuasively by the late Benjamin Freedman and his colleagues, who advanced two arguments in support of this ethical stance. First, the use of placebo-controlled trials in the face of proven effective treatments violates the physician's therapeutic obligation to offer optimal medical care to patients. Second, testing new treatments against placebo when proven effective treatments exist lacks scientific and clinical merit. These two arguments are linked by the principle of clinical equipoise, first formulated by Freedman. This chapter rejects both arguments, claiming that they fail to withstand critical scrutiny in light of the ethically fundamental distinction between clinical research and clinical care, as well as appropriate ethical standards of risk-benefit assessment for clinical research. It argues that the principle of clinical equipoise confuses the ethics of clinical research with the ethics of clinical medicine and that its ethical guidance on the use of placebo-controlled trials is erroneous.