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An internal pilot study for a randomized trial aimed at evaluating the effectiveness of iron interventions in children with non-anemic iron deficiency: the OptEC trial
BACKGROUND: The OptEC trial aims to evaluate the effectiveness of oral iron in young children with non-anemic iron deficiency (NAID). The initial sample size calculated for the OptEC trial ranged from 112–198 subjects. Given the uncertainty regarding the parameters used to calculate the sample, an i...
Autores principales: | , , , , , , , , , |
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Formato: | Online Artículo Texto |
Lenguaje: | English |
Publicado: |
BioMed Central
2015
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Materias: | |
Acceso en línea: | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4501099/ https://www.ncbi.nlm.nih.gov/pubmed/26170014 http://dx.doi.org/10.1186/s13063-015-0829-4 |
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author | Abdullah, Kawsari Thorpe, Kevin E. Mamak, Eva Maguire, Jonathon L. Birken, Catherine S. Fehlings, Darcy Hanley, Anthony J. Macarthur, Colin Zlotkin, Stanley H. Parkin, Patricia C. |
author_facet | Abdullah, Kawsari Thorpe, Kevin E. Mamak, Eva Maguire, Jonathon L. Birken, Catherine S. Fehlings, Darcy Hanley, Anthony J. Macarthur, Colin Zlotkin, Stanley H. Parkin, Patricia C. |
author_sort | Abdullah, Kawsari |
collection | PubMed |
description | BACKGROUND: The OptEC trial aims to evaluate the effectiveness of oral iron in young children with non-anemic iron deficiency (NAID). The initial sample size calculated for the OptEC trial ranged from 112–198 subjects. Given the uncertainty regarding the parameters used to calculate the sample, an internal pilot study was conducted. The objectives of this internal pilot study were to obtain reliable estimate of parameters (standard deviation and design factor) to recalculate the sample size and to assess the adherence rate and reasons for non-adherence in children enrolled in the pilot study. METHODS: The first 30 subjects enrolled into the OptEC trial constituted the internal pilot study. The primary outcome of the OptEC trial is the Early Learning Composite (ELC). For estimation of the SD of the ELC, descriptive statistics of the 4 month follow-up ELC scores were assessed within each intervention group. The observed SD within each group was then pooled to obtain an estimated SD (S(2)) of the ELC. Correlation (ρ) between the ELC measured at baseline and follow-up was assessed. Recalculation of the sample size was performed using analysis of covariance (ANCOVA) method which uses the design factor (1- ρ(2)). Adherence rate was calculated using a parent reported rate of missed doses of the study intervention. CONCLUSION: The new estimate of the SD of the ELC was found to be 17.40 (S(2)). The design factor was (1- ρ2) = 0.21. Using a significance level of 5 %, power of 80 %, S(2 =) 17.40 and effect estimate (Δ) ranging from 6–8 points, the new sample size based on ANCOVA method ranged from 32–56 subjects (16–28 per group). Adherence ranged between 14 % and 100 % with 44 % of the children having an adherence rate ≥86 %. Information generated from our internal pilot study was used to update the design of the full and definitive trial, including recalculation of sample size, determination of the adequacy of adherence, and application of strategies to improve adherence. TRIAL REGISTRATION: ClinicalTrials.gov Identifier: NCT01481766 (date of registration: November 22, 2011). ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1186/s13063-015-0829-4) contains supplementary material, which is available to authorized users. |
format | Online Article Text |
id | pubmed-4501099 |
institution | National Center for Biotechnology Information |
language | English |
publishDate | 2015 |
publisher | BioMed Central |
record_format | MEDLINE/PubMed |
spelling | pubmed-45010992015-07-15 An internal pilot study for a randomized trial aimed at evaluating the effectiveness of iron interventions in children with non-anemic iron deficiency: the OptEC trial Abdullah, Kawsari Thorpe, Kevin E. Mamak, Eva Maguire, Jonathon L. Birken, Catherine S. Fehlings, Darcy Hanley, Anthony J. Macarthur, Colin Zlotkin, Stanley H. Parkin, Patricia C. Trials Update BACKGROUND: The OptEC trial aims to evaluate the effectiveness of oral iron in young children with non-anemic iron deficiency (NAID). The initial sample size calculated for the OptEC trial ranged from 112–198 subjects. Given the uncertainty regarding the parameters used to calculate the sample, an internal pilot study was conducted. The objectives of this internal pilot study were to obtain reliable estimate of parameters (standard deviation and design factor) to recalculate the sample size and to assess the adherence rate and reasons for non-adherence in children enrolled in the pilot study. METHODS: The first 30 subjects enrolled into the OptEC trial constituted the internal pilot study. The primary outcome of the OptEC trial is the Early Learning Composite (ELC). For estimation of the SD of the ELC, descriptive statistics of the 4 month follow-up ELC scores were assessed within each intervention group. The observed SD within each group was then pooled to obtain an estimated SD (S(2)) of the ELC. Correlation (ρ) between the ELC measured at baseline and follow-up was assessed. Recalculation of the sample size was performed using analysis of covariance (ANCOVA) method which uses the design factor (1- ρ(2)). Adherence rate was calculated using a parent reported rate of missed doses of the study intervention. CONCLUSION: The new estimate of the SD of the ELC was found to be 17.40 (S(2)). The design factor was (1- ρ2) = 0.21. Using a significance level of 5 %, power of 80 %, S(2 =) 17.40 and effect estimate (Δ) ranging from 6–8 points, the new sample size based on ANCOVA method ranged from 32–56 subjects (16–28 per group). Adherence ranged between 14 % and 100 % with 44 % of the children having an adherence rate ≥86 %. Information generated from our internal pilot study was used to update the design of the full and definitive trial, including recalculation of sample size, determination of the adequacy of adherence, and application of strategies to improve adherence. TRIAL REGISTRATION: ClinicalTrials.gov Identifier: NCT01481766 (date of registration: November 22, 2011). ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1186/s13063-015-0829-4) contains supplementary material, which is available to authorized users. BioMed Central 2015-07-14 /pmc/articles/PMC4501099/ /pubmed/26170014 http://dx.doi.org/10.1186/s13063-015-0829-4 Text en © Abdullah et al. 2015 This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly credited. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated. |
spellingShingle | Update Abdullah, Kawsari Thorpe, Kevin E. Mamak, Eva Maguire, Jonathon L. Birken, Catherine S. Fehlings, Darcy Hanley, Anthony J. Macarthur, Colin Zlotkin, Stanley H. Parkin, Patricia C. An internal pilot study for a randomized trial aimed at evaluating the effectiveness of iron interventions in children with non-anemic iron deficiency: the OptEC trial |
title | An internal pilot study for a randomized trial aimed at evaluating the effectiveness of iron interventions in children with non-anemic iron deficiency: the OptEC trial |
title_full | An internal pilot study for a randomized trial aimed at evaluating the effectiveness of iron interventions in children with non-anemic iron deficiency: the OptEC trial |
title_fullStr | An internal pilot study for a randomized trial aimed at evaluating the effectiveness of iron interventions in children with non-anemic iron deficiency: the OptEC trial |
title_full_unstemmed | An internal pilot study for a randomized trial aimed at evaluating the effectiveness of iron interventions in children with non-anemic iron deficiency: the OptEC trial |
title_short | An internal pilot study for a randomized trial aimed at evaluating the effectiveness of iron interventions in children with non-anemic iron deficiency: the OptEC trial |
title_sort | internal pilot study for a randomized trial aimed at evaluating the effectiveness of iron interventions in children with non-anemic iron deficiency: the optec trial |
topic | Update |
url | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4501099/ https://www.ncbi.nlm.nih.gov/pubmed/26170014 http://dx.doi.org/10.1186/s13063-015-0829-4 |
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