BMJ  2007;334:918 (5 May), doi:10.1136/bmj.39199.461644.3A

Letters

Masking or blinding?

Blinding is better than masking

The first 150 words of the full text of this article appear below.

We agree with Morris et al that "blinding" terminology is probably inappropriate in ophthalmological settings.¹ However, we disagree that these settings should ordain terminology for all randomised trials. They describe "masking" done in 1784 and provide dictionary definitions of masking and blinding to buttress their argument for using masking terminology. The techniques used in 1784, however, were not termed masking, and regular dictionaries do not adequately define methodological terms for clinical trials.

Blinding in clinical research enjoys a splendid history spanning over two centuries.² Over the years it became entrenched in the tenets of medical research, and most researchers and readers grasp its meaning, although they have more difficulty understanding the different types of blinding.³ Evidently, "blinding" terminology surfaced when Antoine Lavoisier and Benjamin Franklin actually blindfolded (not masked) participants to shelter them from knowledge in their evaluations of the therapeutic claims made for mesmerism.⁴ The visual imagery of blindfolding, . . . [Full text of this article]

¹ Family Health International, Research Triangle Park, North Carolina, 27709 USA, ² Centre for Statistics in Medicine, Wolfson College Annexe, Oxford OX2 6UD, ³ Chalmers Research Group, Children's Hospital of Eastern Ontario (CHEO) Research Institute, Ottawa, ON, Canada K1H 8L1

Related Article

Masking is better than blinding

Daniel Morris, Scott Fraser, and Richard Wormald
BMJ 2007 334: 799. [Extract] [Full Text] [PDF]