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Guidance for using pilot studies to inform the design of intervention trials with continuous outcomes

Guidance for using pilot studies to inform the design of intervention trials with continuous outcomes
Guidance for using pilot studies to inform the design of intervention trials with continuous outcomes
Background: a pilot study can be an important step in the assessment of an intervention by providing information to design the future definitive trial. Pilot studies can be used to estimate the recruitment and retention rates and population variance and to provide preliminary evidence of efficacy potential. However, estimation is poor because pilot studies are small, so sensitivity analyses for the main trial’s sample size calculations should be undertaken.

Methods: we demonstrate how to carry out easy-to-perform sensitivity analysis for designing trials based on pilot data using an example. Furthermore, we introduce rules of thumb for the size of the pilot study so that the overall sample size, for both pilot and main trials, is minimized.

Results: the example illustrates how sample size estimates for the main trial can alter dramatically by plausibly varying assumptions. Required sample size for 90% power varied from 392 to 692 depending on assumptions. Some scenarios were not feasible based on the pilot study recruitment and retention rates.

Conclusion: pilot studies can be used to help design the main trial, but caution should be exercised. We recommend the use of sensitivity analyses to assess the robustness of the design assumptions for a main trial.
1179-1349
Bell, Melanie
50caf8ad-a32a-4a48-85af-e5b105037733
Whitehead, Amy
7bd4e1d1-078b-4f2b-bfc9-ed44ba0a195a
Julious, Steven
260b667f-9b84-423e-a2a4-4b33eb505b47
Bell, Melanie
50caf8ad-a32a-4a48-85af-e5b105037733
Whitehead, Amy
7bd4e1d1-078b-4f2b-bfc9-ed44ba0a195a
Julious, Steven
260b667f-9b84-423e-a2a4-4b33eb505b47

Bell, Melanie, Whitehead, Amy and Julious, Steven (2018) Guidance for using pilot studies to inform the design of intervention trials with continuous outcomes. Clinical Epidemiology. (doi:10.2147/CLEP.S146397).

Record type: Article

Abstract

Background: a pilot study can be an important step in the assessment of an intervention by providing information to design the future definitive trial. Pilot studies can be used to estimate the recruitment and retention rates and population variance and to provide preliminary evidence of efficacy potential. However, estimation is poor because pilot studies are small, so sensitivity analyses for the main trial’s sample size calculations should be undertaken.

Methods: we demonstrate how to carry out easy-to-perform sensitivity analysis for designing trials based on pilot data using an example. Furthermore, we introduce rules of thumb for the size of the pilot study so that the overall sample size, for both pilot and main trials, is minimized.

Results: the example illustrates how sample size estimates for the main trial can alter dramatically by plausibly varying assumptions. Required sample size for 90% power varied from 392 to 692 depending on assumptions. Some scenarios were not feasible based on the pilot study recruitment and retention rates.

Conclusion: pilot studies can be used to help design the main trial, but caution should be exercised. We recommend the use of sensitivity analyses to assess the robustness of the design assumptions for a main trial.

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CLEP-146397-guidance-for-using-pilot-studies-to-inform-the-design-of-int_011718
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More information

Accepted/In Press date: 14 November 2017
e-pub ahead of print date: 1 January 2018
Published date: January 2018

Identifiers

Local EPrints ID: 421812
URI: https://eprints.soton.ac.uk/id/eprint/421812
ISSN: 1179-1349
PURE UUID: dff53842-f36e-478c-98da-e2918b054498

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Date deposited: 28 Jun 2018 16:30
Last modified: 13 Mar 2019 18:23

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Contributors

Author: Melanie Bell
Author: Amy Whitehead
Author: Steven Julious

University divisions

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