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

Jonathan A. Cook* (Corresponding Author), Steven A. Julious, William Sones, Lisa V. Hampson, Catherine Hewitt, Jesse A. Berlin, Deborah Ashby, Richard Emsley, Dean A. Fergusson, Stephen J. Walters, Edward C.F. Wilson, Graeme Maclennan, Nigel Stallard, Joanne C. Rothwell, Martin Bland, Louise Brown, Craig R. Ramsay, Andrew Cook, David Armstrong, Doug AltmanLuke D. Vale

*Corresponding author for this work

Research output: Contribution to journalArticle

4 Citations (Scopus)
4 Downloads (Pure)

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.

Original languageEnglish
Article number606
JournalTrials
Volume19
DOIs
Publication statusPublished - 5 Nov 2018

Fingerprint

Sample Size
Randomized Controlled Trials
Research Personnel
Delphi Technique
Patient Advocacy

ASJC Scopus subject areas

  • Medicine (miscellaneous)
  • Pharmacology (medical)

Cite this

DELTA2 guidance on choosing the target difference and undertaking and reporting the sample size calculation for a randomised controlled trial. / Cook, Jonathan A. (Corresponding Author); Julious, Steven A.; Sones, William; Hampson, Lisa V.; Hewitt, Catherine; Berlin, Jesse A.; Ashby, Deborah; Emsley, Richard; Fergusson, Dean A.; Walters, Stephen J.; Wilson, Edward C.F.; Maclennan, Graeme; Stallard, Nigel; Rothwell, Joanne C.; Bland, Martin; Brown, Louise; Ramsay, Craig R.; Cook, Andrew; Armstrong, David; Altman, Doug; Vale, Luke D.

In: Trials, Vol. 19, 606, 05.11.2018.

Research output: Contribution to journalArticle

Cook, JA, Julious, SA, Sones, W, Hampson, LV, Hewitt, C, Berlin, JA, Ashby, D, Emsley, R, Fergusson, DA, Walters, SJ, Wilson, ECF, Maclennan, G, Stallard, N, Rothwell, JC, Bland, M, Brown, L, Ramsay, CR, Cook, A, Armstrong, D, Altman, D & Vale, LD 2018, 'DELTA2 guidance on choosing the target difference and undertaking and reporting the sample size calculation for a randomised controlled trial', Trials, vol. 19, 606. https://doi.org/10.1186/s13063-018-2884-0
Cook, Jonathan A. ; Julious, Steven A. ; Sones, William ; Hampson, Lisa V. ; Hewitt, Catherine ; Berlin, Jesse A. ; Ashby, Deborah ; Emsley, Richard ; Fergusson, Dean A. ; Walters, Stephen J. ; Wilson, Edward C.F. ; Maclennan, Graeme ; Stallard, Nigel ; Rothwell, Joanne C. ; Bland, Martin ; Brown, Louise ; Ramsay, Craig R. ; Cook, Andrew ; Armstrong, David ; Altman, Doug ; Vale, Luke D. / DELTA2 guidance on choosing the target difference and undertaking and reporting the sample size calculation for a randomised controlled trial. In: Trials. 2018 ; Vol. 19.
@article{fbb99b2c619b4ff5bdef7fffcd675889,
title = "DELTA2 guidance on choosing the target difference and undertaking and reporting the sample size calculation for a randomised controlled trial",
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.",
author = "Cook, {Jonathan A.} and Julious, {Steven A.} and William Sones and Hampson, {Lisa V.} and Catherine Hewitt and Berlin, {Jesse A.} and Deborah Ashby and Richard Emsley and Fergusson, {Dean A.} and Walters, {Stephen J.} and Wilson, {Edward C.F.} and Graeme Maclennan and Nigel Stallard and Rothwell, {Joanne C.} and Martin Bland and Louise Brown and Ramsay, {Craig R.} and Andrew Cook and David Armstrong and Doug Altman and Vale, {Luke D.}",
note = "Funding Funding for this work was received from the MRC/NIHR MRP in response to an open commissioned call for an Effect Size Methodology State-of-the-art Workshop. The Health Services Research Unit, Institute of Applied Health Sciences (University of Aberdeen), is core-funded by the Chief Scientist Office of the Scottish Government Health and Social Care Directorates. The funders had no involvement in study design, collection, analysis and interpretation of data, reporting or the decision to publish.",
year = "2018",
month = "11",
day = "5",
doi = "10.1186/s13063-018-2884-0",
language = "English",
volume = "19",
journal = "Trials",
issn = "1745-6215",
publisher = "BioMed Central",

}

TY - JOUR

T1 - DELTA2 guidance on choosing the target difference and undertaking and reporting the sample size calculation for a randomised controlled trial

AU - Cook, Jonathan A.

AU - Julious, Steven A.

AU - Sones, William

AU - Hampson, Lisa V.

AU - Hewitt, Catherine

AU - Berlin, Jesse A.

AU - Ashby, Deborah

AU - Emsley, Richard

AU - Fergusson, Dean A.

AU - Walters, Stephen J.

AU - Wilson, Edward C.F.

AU - Maclennan, Graeme

AU - Stallard, Nigel

AU - Rothwell, Joanne C.

AU - Bland, Martin

AU - Brown, Louise

AU - Ramsay, Craig R.

AU - Cook, Andrew

AU - Armstrong, David

AU - Altman, Doug

AU - Vale, Luke D.

N1 - Funding Funding for this work was received from the MRC/NIHR MRP in response to an open commissioned call for an Effect Size Methodology State-of-the-art Workshop. The Health Services Research Unit, Institute of Applied Health Sciences (University of Aberdeen), is core-funded by the Chief Scientist Office of the Scottish Government Health and Social Care Directorates. The funders had no involvement in study design, collection, analysis and interpretation of data, reporting or the decision to publish.

PY - 2018/11/5

Y1 - 2018/11/5

N2 - 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.

AB - 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.

UR - http://www.scopus.com/inward/record.url?scp=85056093774&partnerID=8YFLogxK

U2 - 10.1186/s13063-018-2884-0

DO - 10.1186/s13063-018-2884-0

M3 - Article

C2 - 30400926

AN - SCOPUS:85056093774

VL - 19

JO - Trials

JF - Trials

SN - 1745-6215

M1 - 606

ER -