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DELTA2 guidance on choosing the target difference and undertaking and reporting the sample size calculation for a randomised controlled trial

DELTA2 guidance on choosing the target difference and undertaking and reporting the sample size calculation for a randomised controlled trial
DELTA2 guidance on choosing the target difference and undertaking and reporting the sample size calculation for a randomised controlled trial
Background: A key step in the design of a RCT is the estimation of the number of participants needed in the study. The most common approach is to specify a target difference between the treatments for the primary outcome and then calculate the required sample size. The sample size is chosen to ensure that the trial will have a high probability (adequate statistical power) of detecting a target difference between the treatments should one exist.
The sample size has many implications for the conduct and interpretation of the study. Despite the critical role that the target difference has in the design of a RCT, the way in which it is determined has received little attention. In this article, we summarise the key considerations and messages from new guidance for researchers and funders on specifying the target difference, and undertaking and reporting a RCT sample size calculation. This article on choosing the target difference for a randomised controlled trial (RCT) and undertaking and reporting the sample size calculation has been dual published in the BMJ and BMC Trials journals
Methods: The DELTA2 (Difference ELicitation in TriAls) project comprised five major components: systematic literature reviews of recent methodological developments (stage 1) and existing funder guidance (stage 2); a Delphi study (stage 3); a two-day consensus meeting bringing together researchers, funders and patient representatives (stage 4); and the preparation and dissemination of a guidance document (stage 5).
Results and Discussion: The key messages from the DELTA2 guidance on determining the target difference and sample size calculation for a randomised caontrolled trial are presented. Recommendations for the subsequent reporting of the sample size calculation are also provided.
RCT, trial, sample size, guidance, reporting
1745-6215
Cook, Jonathan
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Julious, Steven
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Sones, William
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Hampson, Lisa
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Hewitt, Catherine
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Berlin, Jesse
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Ashby, Deborah
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Emsley, Richard
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Fergusson, Dean
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Walters, Stephen J.
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Wilson, Edward
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MacLennan, Graeme
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Stallard, Nigel
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Rothwell, Joanne
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Bland, Martin
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Brown, Louise
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Ramsay, Craig
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Cook, Andrew
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Armstrong, David
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Altman, Douglas
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Vale, Luke
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Cook, Jonathan
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Julious, Steven
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Sones, William
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Hampson, Lisa
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Hewitt, Catherine
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Berlin, Jesse
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Ashby, Deborah
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Emsley, Richard
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Fergusson, Dean
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Walters, Stephen J.
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Wilson, Edward
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MacLennan, Graeme
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Stallard, Nigel
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Rothwell, Joanne
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Bland, Martin
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Brown, Louise
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Ramsay, Craig
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Cook, Andrew
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Armstrong, David
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Altman, Douglas
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Vale, Luke
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Cook, Jonathan, Julious, Steven, Sones, William, Hampson, Lisa, Hewitt, Catherine, Berlin, Jesse, Ashby, Deborah, Emsley, Richard, Fergusson, Dean, Walters, Stephen J., Wilson, Edward, MacLennan, Graeme, Stallard, Nigel, Rothwell, Joanne, Bland, Martin, Brown, Louise, Ramsay, Craig, Cook, Andrew, Armstrong, David, Altman, Douglas and Vale, Luke (2018) DELTA2 guidance on choosing the target difference and undertaking and reporting the sample size calculation for a randomised controlled trial. Trials, 19, [606]. (doi:10.1186/s13063-018-2884-0).

Record type: Article

Abstract

Background: A key step in the design of a RCT is the estimation of the number of participants needed in the study. The most common approach is to specify a target difference between the treatments for the primary outcome and then calculate the required sample size. The sample size is chosen to ensure that the trial will have a high probability (adequate statistical power) of detecting a target difference between the treatments should one exist.
The sample size has many implications for the conduct and interpretation of the study. Despite the critical role that the target difference has in the design of a RCT, the way in which it is determined has received little attention. In this article, we summarise the key considerations and messages from new guidance for researchers and funders on specifying the target difference, and undertaking and reporting a RCT sample size calculation. This article on choosing the target difference for a randomised controlled trial (RCT) and undertaking and reporting the sample size calculation has been dual published in the BMJ and BMC Trials journals
Methods: The DELTA2 (Difference ELicitation in TriAls) project comprised five major components: systematic literature reviews of recent methodological developments (stage 1) and existing funder guidance (stage 2); a Delphi study (stage 3); a two-day consensus meeting bringing together researchers, funders and patient representatives (stage 4); and the preparation and dissemination of a guidance document (stage 5).
Results and Discussion: The key messages from the DELTA2 guidance on determining the target difference and sample size calculation for a randomised caontrolled trial are presented. Recommendations for the subsequent reporting of the sample size calculation are also provided.

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Accepted/In Press date: 29 August 2018
e-pub ahead of print date: 5 November 2018
Published date: 5 November 2018
Keywords: RCT, trial, sample size, guidance, reporting

Identifiers

Local EPrints ID: 426024
URI: http://eprints.soton.ac.uk/id/eprint/426024
ISSN: 1745-6215
PURE UUID: 0467a809-26c7-487c-a643-bf0e1dda609c
ORCID for Andrew Cook: ORCID iD orcid.org/0000-0002-6680-439X

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Date deposited: 09 Nov 2018 17:30
Last modified: 11 May 2024 01:41

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Contributors

Author: Jonathan Cook
Author: Steven Julious
Author: William Sones
Author: Lisa Hampson
Author: Catherine Hewitt
Author: Jesse Berlin
Author: Deborah Ashby
Author: Richard Emsley
Author: Dean Fergusson
Author: Stephen J. Walters
Author: Edward Wilson
Author: Graeme MacLennan
Author: Nigel Stallard
Author: Joanne Rothwell
Author: Martin Bland
Author: Louise Brown
Author: Craig Ramsay
Author: Andrew Cook ORCID iD
Author: David Armstrong
Author: Douglas Altman
Author: Luke Vale

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