Towards more credible shams for physical interventions: A Delphi survey.

Experts agreed that, for shams to be believable, consideration of cognitive influences is essential. Contrary to the focus of previous shams for physical interventions, replicating the tactile sensation of the active treatment was not considered an essential part of sham development. Therefore, when designing sham-controlled clinical trials, researchers should carefully consider the cognitive credibility of the entire intervention experience, and not just the indistinguishability of the sham intervention itself. The findings provide new guidance to researchers on important contributors to blinding in physical intervention trials.