Abstract

This article explores some implications of the increasing reliance on clinical trials in contemporary health care, particularly health care payers’ efforts to use them in the so-called fourth hurdle decisions. How do these agencies manage medical uncertainty given the desire to produce clear guidelines for clinicians? Their solutions take account of trials in at least two ways, reflecting broader debates about the meaning of these medical experiments. Trials can be read as either ‘‘proofs of protocol’’—straightforward guides to action with individual drugs in specific populations—or ‘‘proofs of principle’’— where extrapolation is made possible through an appeal to underlying biological mechanisms. These contrasting readings of trials are illustrated with reference to guidelines on heart disease prevention/cholesterol reduction using statins among the elderly in North America and the United Kingdom. Uncertainty in these cases does not lead to inertia but solutions use different fixed points to aid navigation, including both physiological principles and moral values.