Equipoise

Clinical equipoise provides the ethical basis for conduct of randomized clinical trials. This principal states that a clinical trial is acceptable only insofar as there is professional disagreement between researchers concerning uncertainty regarding the outcome of the study.1and thus even if a clinician prefers one arm over another, randomization is still sound when there are others who believe the other way around.

However, there are often conflicts between regulatory and investigator regarding the interpretation of equipoise and biases generated from publications suggestive of the efficacy of one product over another may cause lack of equipoise. Lack of clinical equipoise causes unwillingness at the investigator level to enroll patients because of strong belief by the majority of physicians in one treatment being superior over another. This results in difficultly in designing studies to support licensing a product such that physicians are unwilling to participate in a study that is necessary to satisfy regulatory agency(s) requirements for trial data demonstrating efficacy and safety.

References:
Freedman B: Equipoise and the ethics of clinical research. N Engl J Med 317: 141-145, 1987
Lilford RJ Declaratio of Helsinki should be strengthened. BMJ 322(7281) 299
Ashcroft R: Equipoise, knowledge and ethics in clinical research and practice. Bioethics 13 (3/4):314-326, 1999
Royall RM: Ethic and Statistics in Randomized Clinical trials. Statistical science 6(1): 52-66 1991