Blinding assessment in clinical trials: A review of statistical methods and a proposal of blinding assessment protocol

There is strong consensus in the clinical trial community that blinding is an important issue in randomized controlled trials. At present grossly incomplete reporting of procedures and the use of any assessment for blinding still prevails. The term ‘double-blind’ has almost become a convention without any checks or balances. Also there is a lack of consensus on quantitative procedures for evaluating the success of blinding in the literature. This article reviews statistical methods of blinding assessment along with software options, and discusses some of the most pressing issues surrounding the acquisition, interpretation, and reporting of blinding data. Finally, it proposes a sample blinding assessment protocol to address some of these issues.