BMJ  2004;328:1135 (8 May), doi:10.1136/bmj.328.7448.1135-a

Letter

Turning a blind eye

Testing the success of blinding and the CONSORT statement

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

EDITOR—Reports of randomised trials should state clearly whether blinding was attempted, and if so who was blinded and how this was done.¹ Fergusson et al note that blinding may be ineffective in some trials, making them less sound methodologically than they seem to be.²

But trial participants asked to guess the treatment they received might well be influenced by outcome. We might expect to see an apparent breaking of the blind more often in trials when the effect of treatment was a marked, for either an intended outcome or adverse effect. Indeed, end of trial tests of blindness might be tests of hunches for adverse effects or efficacy.^{3 4} Assessments of blinding success would be much more reliable in trials when they can be carried out before the clinical outcome has been determined.

Furthermore, those who successfully decipher assignments may disguise their unblinding actions.^{3 4} That difficulty, along with the . . . [Full text of this article]

Cancer Research UK Medical Statistics Group, Centre for Statistics in Medicine, Oxford OX3 7LF doug.altman@cancer.org.uk

Quantitative Sciences, Family Health International, Research Triangle Park, NC, USA

Chalmers Research Group, Children's Hospital of Eastern Ontario, University of Ottawa, Ottawa, ON, Canada

CiteULike    Complore    Connotea    Del.icio.us    Digg    Reddit    Technorati    What's this?

Related Article

Turning a blind eye: the success of blinding reported in a random sample of randomised, placebo controlled trials

Dean Fergusson, Kathleen Cranley Glass, Duff Waring, and Stan Shapiro
BMJ 2004 328: 432. [Abstract] [Full Text] [PDF]

This article has been cited by other articles:

• Boutron, I., Moher, D., Altman, D. G., Schulz, K. F., Ravaud, P., for the CONSORT Group, (2008). Extending the CONSORT Statement to Randomized Trials of Nonpharmacologic Treatment: Explanation and Elaboration. ANN INTERN MED 148: 295-309 [Abstract] [Full text]  
• Wagena, E. J., Knipschild, P. G., Huibers, M. J. H., Wouters, E. F. M., van Schayck, C. P. (2005). Efficacy of Bupropion and Nortriptyline for Smoking Cessation Among People at Risk for or With Chronic Obstructive Pulmonary Disease. Arch Intern Med 165: 2286-2292 [Abstract] [Full text]