A clinical trial involves decisions at three distinct levels: society, individual physician, patient.

The decision on whether a proposed trial should be carried out is formally taken by the Research Ethics Board (REB), which, in effect, must decide whether asking patients to consent to participate is consistent with the standards of society as a whole. The concept of "clinical equipoise" is an essential part of the REB’s decision; the REB must be confident that expert clinical opinion regards the trial as valid.

Individual clinicians must decide whether they should enter patients into the trial. The concept of "uncertainty" addresses this decision.

The consent of the patient is requested by the uncertain physician on a case-by-case basis if (s)he believes that the uncertainty for a population of patients applies in each specific case.

The term "clinical equipoise", though perhaps ungainly, effectively captures the valuable concept of collective expert uncertainty, and differentiates it from individual uncertainty, which may be insufficient justification for a trial.

Francis Rolleston
Canadian Institutes of Health Research
Ottawa, ON (Until December 1, 2000)

500 Denbury Avenue
Ottawa, ON (After December 1, 2000)

1. Sackett DL. Why randomized controlled trials fail but needn’t: 1. Failure to gain "coal-face" commitment and to use the uncertainty principle. CMAJ 2000;162(9):1311-4.
2. Sackett DL. Equipoise, a term whose time (if it ever came) has surely gone. CMAJ 2000;163(7):835-6.
3. Shapiro SH, Glass KC, Why Sackett’s analysis of randomized controlled trials fails, but needn’t. CMAJ 2000;163(7):834-5.