Placebo Orthodoxy in Clinical Research I: Empirical and Methodological Myths

Abstract

The use of statistics in medical research has been compared to a religion: it has its high priests (statisticians), supplicants (journal editors and researchers), and orthodoxy (for example, p <.05 is significant). Although the comparison may be more unfair to religion than to research, a useful lesson can nonetheless be drawn: the practice of clinical research may benefit—as does the spirit—from critical self-examination. Arguably, no aspect of the conduct of clinical trials is currently more controversial—and thus in as dire need of critical examination—than the use of placebo controls. The ethical and scientific controversies associated with placebo-controlled trials, never far below the surface, have once again seized public attention. Clearly, concern about these issues within the professional community runs deep and wide, as evidenced by the volume of response generated by Kenneth Rothman and Karin Michels's recent Critique. Criticisms of the use of placebo controls in clinical research are scattered through the literatureo; our objective is to present the case against placebos in a compendious form that takes account of scientific and statistical as well as normative issues.