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J Clin Epidemiol. 2009 Sep;62(9):967-73. doi: 10.1016/j.jclinepi.2009.04.003.

Reporting on blinding in trial protocols and corresponding publications was often inadequate but rarely contradictory.

Author information

1
The Nordic Cochrane Centre, Rigshospitalet, Copenhagen, Denmark. ah@cochrane.dk

Abstract

OBJECTIVE:

To compare the reporting on blinding in protocols and articles describing randomized controlled trials.

STUDY DESIGN AND SETTING:

We studied 73 protocols of trials approved by the scientific/ethical committees for Copenhagen and Frederiksberg, 1994 and 1995, and their corresponding publications.

RESULTS:

Three out of 73 trials (4%) reported blinding in the protocol that contradicted that in the publication (e.g., "open" vs. "double blind"). The proportion of "double-blind" trials with a clear description of the blinding of participants increased from 11 out of 58 (19%) when based on publications alone to 39 (67%) when adding the information in the protocol. The similar proportions for the blinding of health care providers were 2 (3%) and 22 (38%); and for the blinding of data collectors, they were 8 (14%) and 14 (24%). In 52 of 58 publications (90%), it was unclear whether all patients, health care providers, and data collectors had been blinded. In 4 of the 52 trials (7%), the protocols clarified that all three key trial persons had been blinded.

CONCLUSIONS:

The reporting on blinding in both trial protocols and publications is often inadequate. We suggest developing international guidelines for the reporting of trial protocols and public access to protocols.

PMID:
19635403
DOI:
10.1016/j.jclinepi.2009.04.003
[Indexed for MEDLINE]

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