Practical tips for surgical research: blinding: who, what, when, why, how?

Abstract

Blinding refers to the concealment of group allocation from one or more individuals involved in a clinical research study, most commonly a randomized controlled trial (RCT). Although randomization minimizes differences between treatment groups at the outset of the trial, it does nothing to prevent differential treatment of the groups later in the trial or the differential assessment of outcomes, either of which may result in biased estimates of treatment effects. The optimal strategy to minimize the likelihood of differential treatment or assessments of outcomes is to blind as many individuals as possible in a trial. Randomized controlled trials of surgical interventions are frequently more difficult to blind than RCTs of medications, which typically achieve blinding with placebos. However, imaginative techniques may make blinding more feasible in surgical trials than is commonly believed by many researchers. In this article we discuss the importance of blinding and provide practical suggestions to researchers who wish to incorporate blinding into their surgical studies.