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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 po...

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Autores principales: Bell, Melanie L, Whitehead, Amy L, Julious, Steven A
Formato: Online Artículo Texto
Lenguaje:English
Publicado: Dove Medical Press 2018
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5779280/
https://www.ncbi.nlm.nih.gov/pubmed/29403314
http://dx.doi.org/10.2147/CLEP.S146397
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author Bell, Melanie L
Whitehead, Amy L
Julious, Steven A
author_facet Bell, Melanie L
Whitehead, Amy L
Julious, Steven A
author_sort Bell, Melanie L
collection PubMed
description 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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spelling pubmed-57792802018-02-05 Guidance for using pilot studies to inform the design of intervention trials with continuous outcomes Bell, Melanie L Whitehead, Amy L Julious, Steven A Clin Epidemiol Methodology 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. Dove Medical Press 2018-01-18 /pmc/articles/PMC5779280/ /pubmed/29403314 http://dx.doi.org/10.2147/CLEP.S146397 Text en © 2018 Bell et al. This work is published and licensed by Dove Medical Press Limited The full terms of this license are available at https://www.dovepress.com/terms.php and incorporate the Creative Commons Attribution – Non Commercial (unported, v3.0) License (http://creativecommons.org/licenses/by-nc/3.0/). By accessing the work you hereby accept the Terms. Non-commercial uses of the work are permitted without any further permission from Dove Medical Press Limited, provided the work is properly attributed.
spellingShingle Methodology
Bell, Melanie L
Whitehead, Amy L
Julious, Steven A
Guidance for using pilot studies to inform the design of intervention trials with continuous outcomes
title Guidance for using pilot studies to inform the design of intervention trials with continuous outcomes
title_full Guidance for using pilot studies to inform the design of intervention trials with continuous outcomes
title_fullStr Guidance for using pilot studies to inform the design of intervention trials with continuous outcomes
title_full_unstemmed Guidance for using pilot studies to inform the design of intervention trials with continuous outcomes
title_short Guidance for using pilot studies to inform the design of intervention trials with continuous outcomes
title_sort guidance for using pilot studies to inform the design of intervention trials with continuous outcomes
topic Methodology
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5779280/
https://www.ncbi.nlm.nih.gov/pubmed/29403314
http://dx.doi.org/10.2147/CLEP.S146397
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