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Rapid response to:

Research Methods & Reporting

CONSORT 2010 Statement: updated guidelines for reporting parallel group randomised trials

BMJ 2010; 340 doi: (Published 24 March 2010) Cite this as: BMJ 2010;340:c332

Rapid Response:

Re: Testing for blinding is the only way to determine whether a trial is blind

Colagiuri and Benedetti, in their Rapid Response, wrote that we
ignored a growing body of research that stresses the importance of
evaluating blinding, yet they did not describe how that research supports
their views. We did not ignore that research. We just came to a different
interpretation than Colagiuri and Benedetti, considering the totality of

We anticipated that some researchers might question the reasoning
behind CONSORT 2010 removing mention of how the success of blinding might
have been evaluated. Thus, with the simultaneous publication of CONSORT
2010 in 9 journals on March 24, 2010, that same day we also published a
Comment in the online version of The Lancet that explained our reasoning.
It was subsequently published in print on April 3, 2010.(1) We direct
Colagiruri, Benedetti, and other readers to that Comment for our
rationale, and for some potential alternatives to tests of blindness.(1)

Readers should recognize that CONSORT only addresses reporting.
CONSORT has not addressed conduct thus far, and will not directly
recommend specific conduct in the future. In other words, CONSORT 2010
does not recommend for or against testing the success of blinding, and
does not proscribe, or even recommend against, the reporting of such

The CONSORT Group is only able to include a minimal set of items in
the checklist for reporting a randomized trial, and we strive to be
evidence-based wherever possible. In this case, we believe that the
methods used in assessing the success of blinding have interpretational
difficulties, leading us to question their usefulness in many
circumstances. While such tests could be beneficial for certain trials,
our judgment reflects a broad appraisal that, in general, reporting tests
of blindness does not cross our minimal reporting criteria threshold.

We emphasize that CONSORT 2010 is a generic minimum, indicating those
aspects of a trial we would expect to see in all trial reports. Trialists
should transparently and clearly describe their trial, and that may
include additional information in their trial report. Those who have
assessed the success of blinding should certainly feel free to report
their findings.

Kenneth F. Schulz, PhD

Douglas G. Altman, DSc

David Moher, PhD

Reference List

1. Schulz KF, Altman DG, Moher D, Fergusson D. CONSORT 2010 changes
and testing blindness in RCTs. Lancet 2010;375(9721):1144-6.

Competing interests:
None declared

Competing interests: No competing interests

27 May 2010
Kenneth F. Schulz
Distinguished Scientist and VP
Douglas G. Altman and David Moher
FHI, P.O. Box 13950 Research Triangle Park, NC 27709