The use of equipoise in clinical trials

Randomised control trials (RCTs) are the standard method for treatment evaluation. Unfortunately RCTs are inherently difficult to recruit for, precisely because of the randomisation element that makes them so statistically attractive. Problems of low recruitment are now beginning to impact on trials, with many either not being started or being forced to stop, due to lack of participation. This paper examines one issue that bears on the recruitment problem: equipoise. Equipoise is defined as the point where a rational, informed person has no preference between two (or more) available treatments (Lilford and Jackson, 1995). The use of equipoise as the fundamental criterion for eligibility for a trial seems to impose a hurdle to recruitment. Here we examine the various arguments surrounding its use and measurement. We conclude that effective equipoise based upon constructed "zones of indifference" offers the best chance for bridging the gap between the individual's right to decide and the need for clinical trials to benefit society.