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Reporting of statistically significant results at ClinicalTrials.gov for completed superiority randomized controlled trials

BACKGROUND: Publication bias and other reporting bias have been well documented for journal articles, but no study has evaluated the nature of results posted at ClinicalTrials.gov. We aimed to assess how many randomized controlled trials (RCTs) with results posted at ClinicalTrials.gov report statis...

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Autores principales: Dechartres, Agnes, Bond, Elizabeth G., Scheer, Jordan, Riveros, Carolina, Atal, Ignacio, Ravaud, Philippe
Formato: Online Artículo Texto
Lenguaje:English
Publicado: BioMed Central 2016
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5129217/
https://www.ncbi.nlm.nih.gov/pubmed/27899150
http://dx.doi.org/10.1186/s12916-016-0740-1
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author Dechartres, Agnes
Bond, Elizabeth G.
Scheer, Jordan
Riveros, Carolina
Atal, Ignacio
Ravaud, Philippe
author_facet Dechartres, Agnes
Bond, Elizabeth G.
Scheer, Jordan
Riveros, Carolina
Atal, Ignacio
Ravaud, Philippe
author_sort Dechartres, Agnes
collection PubMed
description BACKGROUND: Publication bias and other reporting bias have been well documented for journal articles, but no study has evaluated the nature of results posted at ClinicalTrials.gov. We aimed to assess how many randomized controlled trials (RCTs) with results posted at ClinicalTrials.gov report statistically significant results and whether the proportion of trials with significant results differs when no treatment effect estimate or p-value is posted. METHODS: We searched ClinicalTrials.gov in June 2015 for all studies with results posted. We included completed RCTs with a superiority hypothesis and considered results for the first primary outcome with results posted. For each trial, we assessed whether a treatment effect estimate and/or p-value was reported at ClinicalTrials.gov and if yes, whether results were statistically significant. If no treatment effect estimate or p-value was reported, we calculated the treatment effect and corresponding p-value using results per arm posted at ClinicalTrials.gov when sufficient data were reported. RESULTS: From the 17,536 studies with results posted at ClinicalTrials.gov, we identified 2823 completed phase 3 or 4 randomized trials with a superiority hypothesis. Of these, 1400 (50%) reported a treatment effect estimate and/or p-value. Results were statistically significant for 844 trials (60%), with a median p-value of 0.01 (Q1-Q3: 0.001–0.26). For the 1423 trials with no treatment effect estimate or p-value posted, we could calculate the treatment effect and corresponding p-value using results reported per arm for 929 (65%). For 494 trials (35%), p-values could not be calculated mainly because of insufficient reporting, censored data, or repeated measurements over time. For the 929 trials we could calculate p-values, we found statistically significant results for 342 (37%), with a median p-value of 0.19 (Q1-Q3: 0.005–0.59). CONCLUSIONS: Half of the trials with results posted at ClinicalTrials.gov reported a treatment effect estimate and/or p-value, with significant results for 60% of these. p-values could be calculated from results reported per arm at ClinicalTrials.gov for only 65% of the other trials. The proportion of significant results was much lower for these trials, which suggests a selective posting of treatment effect estimates and/or p-values when results are statistically significant.
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spelling pubmed-51292172016-12-12 Reporting of statistically significant results at ClinicalTrials.gov for completed superiority randomized controlled trials Dechartres, Agnes Bond, Elizabeth G. Scheer, Jordan Riveros, Carolina Atal, Ignacio Ravaud, Philippe BMC Med Research Article BACKGROUND: Publication bias and other reporting bias have been well documented for journal articles, but no study has evaluated the nature of results posted at ClinicalTrials.gov. We aimed to assess how many randomized controlled trials (RCTs) with results posted at ClinicalTrials.gov report statistically significant results and whether the proportion of trials with significant results differs when no treatment effect estimate or p-value is posted. METHODS: We searched ClinicalTrials.gov in June 2015 for all studies with results posted. We included completed RCTs with a superiority hypothesis and considered results for the first primary outcome with results posted. For each trial, we assessed whether a treatment effect estimate and/or p-value was reported at ClinicalTrials.gov and if yes, whether results were statistically significant. If no treatment effect estimate or p-value was reported, we calculated the treatment effect and corresponding p-value using results per arm posted at ClinicalTrials.gov when sufficient data were reported. RESULTS: From the 17,536 studies with results posted at ClinicalTrials.gov, we identified 2823 completed phase 3 or 4 randomized trials with a superiority hypothesis. Of these, 1400 (50%) reported a treatment effect estimate and/or p-value. Results were statistically significant for 844 trials (60%), with a median p-value of 0.01 (Q1-Q3: 0.001–0.26). For the 1423 trials with no treatment effect estimate or p-value posted, we could calculate the treatment effect and corresponding p-value using results reported per arm for 929 (65%). For 494 trials (35%), p-values could not be calculated mainly because of insufficient reporting, censored data, or repeated measurements over time. For the 929 trials we could calculate p-values, we found statistically significant results for 342 (37%), with a median p-value of 0.19 (Q1-Q3: 0.005–0.59). CONCLUSIONS: Half of the trials with results posted at ClinicalTrials.gov reported a treatment effect estimate and/or p-value, with significant results for 60% of these. p-values could be calculated from results reported per arm at ClinicalTrials.gov for only 65% of the other trials. The proportion of significant results was much lower for these trials, which suggests a selective posting of treatment effect estimates and/or p-values when results are statistically significant. BioMed Central 2016-11-30 /pmc/articles/PMC5129217/ /pubmed/27899150 http://dx.doi.org/10.1186/s12916-016-0740-1 Text en © The Author(s). 2016 Open AccessThis article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. 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 Research Article
Dechartres, Agnes
Bond, Elizabeth G.
Scheer, Jordan
Riveros, Carolina
Atal, Ignacio
Ravaud, Philippe
Reporting of statistically significant results at ClinicalTrials.gov for completed superiority randomized controlled trials
title Reporting of statistically significant results at ClinicalTrials.gov for completed superiority randomized controlled trials
title_full Reporting of statistically significant results at ClinicalTrials.gov for completed superiority randomized controlled trials
title_fullStr Reporting of statistically significant results at ClinicalTrials.gov for completed superiority randomized controlled trials
title_full_unstemmed Reporting of statistically significant results at ClinicalTrials.gov for completed superiority randomized controlled trials
title_short Reporting of statistically significant results at ClinicalTrials.gov for completed superiority randomized controlled trials
title_sort reporting of statistically significant results at clinicaltrials.gov for completed superiority randomized controlled trials
topic Research Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5129217/
https://www.ncbi.nlm.nih.gov/pubmed/27899150
http://dx.doi.org/10.1186/s12916-016-0740-1
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