Blinding in clinical trials: a practical approach.

Blinding is important in the conduct of clinical trials, yet it generally receives less attention and effort than other trial components (e.g., randomization, compliance) that are rigorously treated in the design and/or analysis stages. Furthermore, although the word "blind" commonly appears in the titles of publications, its use is not always well justified. We are human beings, and our behavior or decisions can change depending on whether our eyes are open or closed. That is why virtually everyone in the clinical trial community, including subjects, investigators, treating practitioners, and outcome assessors, would agree that some form of blinding is needed to reach a fair and objective conclusion uninfluenced by knowledge of intervention assignment. Despite our best efforts, however, blinding may not always be successful. There is a considerable body of literature about blinding and the need to assess whether it has been properly implemented and maintained. By discussing how the trialist and the team may handle blinding-related issues in different stages of a clinical trial, this brief article intends to offer reasonable suggestions that could improve current practice, helping researchers deal confidently with blinding-related issues and research in a manner that meets rigorous standards, but is practical and flexible.