Systematic Review of the Empirical Evidence of Study Publication Bias and Outcome Reporting Bias
Identifieur interne : 000437 ( Ncbi/Merge ); précédent : 000436; suivant : 000438Systematic Review of the Empirical Evidence of Study Publication Bias and Outcome Reporting Bias
Auteurs : Kerry Dwan [Royaume-Uni] ; Douglas G. Altman [Royaume-Uni] ; Juan A. Arnaiz [Espagne] ; Jill Bloom [Royaume-Uni] ; An-Wen Chan [Canada] ; Eugenia Cronin [Royaume-Uni] ; Evelyne Decullier [France] ; Philippa J. Easterbrook [Royaume-Uni] ; Erik Von Elm [Suisse, Allemagne] ; Carrol Gamble [Royaume-Uni] ; Davina Ghersi [Australie] ; John P. A. Ioannidis [Grèce, États-Unis] ; John Simes [Australie] ; Paula R. Williamson [Royaume-Uni]Source :
- PLoS ONE [ 1932-6203 ] ; 2008.
Abstract
The increased use of meta-analysis in systematic reviews of healthcare interventions has highlighted several types of bias that can arise during the completion of a randomised controlled trial. Study publication bias has been recognised as a potential threat to the validity of meta-analysis and can make the readily available evidence unreliable for decision making. Until recently, outcome reporting bias has received less attention.
We review and summarise the evidence from a series of cohort studies that have assessed study publication bias and outcome reporting bias in randomised controlled trials. Sixteen studies were eligible of which only two followed the cohort all the way through from protocol approval to information regarding publication of outcomes. Eleven of the studies investigated study publication bias and five investigated outcome reporting bias. Three studies have found that statistically significant outcomes had a higher odds of being fully reported compared to non-significant outcomes (range of odds ratios: 2.2 to 4.7). In comparing trial publications to protocols, we found that 40–62% of studies had at least one primary outcome that was changed, introduced, or omitted. We decided not to undertake meta-analysis due to the differences between studies.
Recent work provides direct empirical evidence for the existence of study publication bias and outcome reporting bias. There is strong evidence of an association between significant results and publication; studies that report positive or significant results are more likely to be published and outcomes that are statistically significant have higher odds of being fully reported. Publications have been found to be inconsistent with their protocols. Researchers need to be aware of the problems of both types of bias and efforts should be concentrated on improving the reporting of trials.
Url:
DOI: 10.1371/journal.pone.0003081
PubMed: 18769481
PubMed Central: 2518111
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PMC:2518111Le document en format XML
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<author><name sortKey="Cronin, Eugenia" sort="Cronin, Eugenia" uniqKey="Cronin E" first="Eugenia" last="Cronin">Eugenia Cronin</name>
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<author><name sortKey="Decullier, Evelyne" sort="Decullier, Evelyne" uniqKey="Decullier E" first="Evelyne" last="Decullier">Evelyne Decullier</name>
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<author><name sortKey="Easterbrook, Philippa J" sort="Easterbrook, Philippa J" uniqKey="Easterbrook P" first="Philippa J." last="Easterbrook">Philippa J. Easterbrook</name>
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<author><name sortKey="Von Elm, Erik" sort="Von Elm, Erik" uniqKey="Von Elm E" first="Erik" last="Von Elm">Erik Von Elm</name>
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<country xml:lang="fr">Suisse</country>
<wicri:regionArea>Institute of Social and Preventive Medicine, University of Bern, Bern</wicri:regionArea>
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<settlement type="city">Berne</settlement>
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<affiliation wicri:level="3"><nlm:aff id="aff10"><addr-line>German Cochrane Centre, Department of Medical Biometry and Medical Informatics, University Medical Centre Freiburg, Freiburg, Germany</addr-line>
</nlm:aff>
<country xml:lang="fr">Allemagne</country>
<wicri:regionArea>German Cochrane Centre, Department of Medical Biometry and Medical Informatics, University Medical Centre Freiburg, Freiburg</wicri:regionArea>
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<author><name sortKey="Gamble, Carrol" sort="Gamble, Carrol" uniqKey="Gamble C" first="Carrol" last="Gamble">Carrol Gamble</name>
<affiliation wicri:level="1"><nlm:aff id="aff1"><addr-line>Centre for Medical Statistics and Health Evaluation, University of Liverpool, Liverpool, United Kingdom</addr-line>
</nlm:aff>
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<author><name sortKey="Ghersi, Davina" sort="Ghersi, Davina" uniqKey="Ghersi D" first="Davina" last="Ghersi">Davina Ghersi</name>
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<country xml:lang="fr">Australie</country>
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<wicri:noRegion>Camperdown</wicri:noRegion>
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<author><name sortKey="Ioannidis, John P A" sort="Ioannidis, John P A" uniqKey="Ioannidis J" first="John P. A." last="Ioannidis">John P. A. Ioannidis</name>
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</nlm:aff>
<country xml:lang="fr">États-Unis</country>
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<placeName><region type="state">Massachusetts</region>
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<author><name sortKey="Simes, John" sort="Simes, John" uniqKey="Simes J" first="John" last="Simes">John Simes</name>
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</nlm:aff>
<country xml:lang="fr">Australie</country>
<wicri:regionArea>National Health and Medical Research Council (NHMRC) Clinical Trials Centre, University of Sydney, Sydney</wicri:regionArea>
<placeName><settlement type="city">Sydney</settlement>
<region type="état">Nouvelle-Galles du Sud</region>
<settlement type="city">Sydney</settlement>
</placeName>
<orgName type="university">Université de Sydney</orgName>
</affiliation>
</author>
<author><name sortKey="Williamson, Paula R" sort="Williamson, Paula R" uniqKey="Williamson P" first="Paula R." last="Williamson">Paula R. Williamson</name>
<affiliation wicri:level="1"><nlm:aff id="aff1"><addr-line>Centre for Medical Statistics and Health Evaluation, University of Liverpool, Liverpool, United Kingdom</addr-line>
</nlm:aff>
<country xml:lang="fr">Royaume-Uni</country>
<wicri:regionArea>Centre for Medical Statistics and Health Evaluation, University of Liverpool, Liverpool</wicri:regionArea>
<wicri:noRegion>Liverpool</wicri:noRegion>
</affiliation>
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<front><div type="abstract" xml:lang="en"><sec><title>Background</title>
<p>The increased use of meta-analysis in systematic reviews of healthcare interventions has highlighted several types of bias that can arise during the completion of a randomised controlled trial. Study publication bias has been recognised as a potential threat to the validity of meta-analysis and can make the readily available evidence unreliable for decision making. Until recently, outcome reporting bias has received less attention.</p>
</sec>
<sec><title>Methodology/Principal Findings</title>
<p>We review and summarise the evidence from a series of cohort studies that have assessed study publication bias and outcome reporting bias in randomised controlled trials. Sixteen studies were eligible of which only two followed the cohort all the way through from protocol approval to information regarding publication of outcomes. Eleven of the studies investigated study publication bias and five investigated outcome reporting bias. Three studies have found that statistically significant outcomes had a higher odds of being fully reported compared to non-significant outcomes (range of odds ratios: 2.2 to 4.7). In comparing trial publications to protocols, we found that 40–62% of studies had at least one primary outcome that was changed, introduced, or omitted. We decided not to undertake meta-analysis due to the differences between studies.</p>
</sec>
<sec><title>Conclusions</title>
<p>Recent work provides direct empirical evidence for the existence of study publication bias and outcome reporting bias. There is strong evidence of an association between significant results and publication; studies that report positive or significant results are more likely to be published and outcomes that are statistically significant have higher odds of being fully reported. Publications have been found to be inconsistent with their protocols. Researchers need to be aware of the problems of both types of bias and efforts should be concentrated on improving the reporting of trials.</p>
</sec>
</div>
</front>
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<pmc article-type="research-article" xml:lang="EN"><pmc-dir>properties open_access</pmc-dir>
<front><journal-meta><journal-id journal-id-type="nlm-ta">PLoS ONE</journal-id>
<journal-id journal-id-type="publisher-id">plos</journal-id>
<journal-id journal-id-type="pmc">plosone</journal-id>
<journal-title>PLoS ONE</journal-title>
<issn pub-type="epub">1932-6203</issn>
<publisher><publisher-name>Public Library of Science</publisher-name>
<publisher-loc>San Francisco, USA</publisher-loc>
</publisher>
</journal-meta>
<article-meta><article-id pub-id-type="pmid">18769481</article-id>
<article-id pub-id-type="pmc">2518111</article-id>
<article-id pub-id-type="publisher-id">07-PONE-RA-02968R1</article-id>
<article-id pub-id-type="doi">10.1371/journal.pone.0003081</article-id>
<article-categories><subj-group subj-group-type="heading"><subject>Research Article</subject>
</subj-group>
<subj-group subj-group-type="Discipline"><subject>Evidence-Based Healthcare</subject>
<subject>Evidence-Based Healthcare/Clinical Decision-Making</subject>
<subject>Evidence-Based Healthcare/Statistical Methodologies and Health Informatics</subject>
</subj-group>
</article-categories>
<title-group><article-title>Systematic Review of the Empirical Evidence of Study Publication Bias and Outcome Reporting Bias</article-title>
<alt-title alt-title-type="running-head">Publication and Reporting Bias</alt-title>
</title-group>
<contrib-group><contrib contrib-type="author"><name><surname>Dwan</surname>
<given-names>Kerry</given-names>
</name>
<xref ref-type="aff" rid="aff1"><sup>1</sup>
</xref>
<xref ref-type="corresp" rid="cor1"><sup>*</sup>
</xref>
</contrib>
<contrib contrib-type="author"><name><surname>Altman</surname>
<given-names>Douglas G.</given-names>
</name>
<xref ref-type="aff" rid="aff2"><sup>2</sup>
</xref>
</contrib>
<contrib contrib-type="author"><name><surname>Arnaiz</surname>
<given-names>Juan A.</given-names>
</name>
<xref ref-type="aff" rid="aff3"><sup>3</sup>
</xref>
</contrib>
<contrib contrib-type="author"><name><surname>Bloom</surname>
<given-names>Jill</given-names>
</name>
<xref ref-type="aff" rid="aff4"><sup>4</sup>
</xref>
</contrib>
<contrib contrib-type="author"><name><surname>Chan</surname>
<given-names>An-Wen</given-names>
</name>
<xref ref-type="aff" rid="aff5"><sup>5</sup>
</xref>
</contrib>
<contrib contrib-type="author"><name><surname>Cronin</surname>
<given-names>Eugenia</given-names>
</name>
<xref ref-type="aff" rid="aff6"><sup>6</sup>
</xref>
</contrib>
<contrib contrib-type="author"><name><surname>Decullier</surname>
<given-names>Evelyne</given-names>
</name>
<xref ref-type="aff" rid="aff7"><sup>7</sup>
</xref>
</contrib>
<contrib contrib-type="author"><name><surname>Easterbrook</surname>
<given-names>Philippa J.</given-names>
</name>
<xref ref-type="aff" rid="aff8"><sup>8</sup>
</xref>
</contrib>
<contrib contrib-type="author"><name><surname>Von Elm</surname>
<given-names>Erik</given-names>
</name>
<xref ref-type="aff" rid="aff9"><sup>9</sup>
</xref>
<xref ref-type="aff" rid="aff10"><sup>10</sup>
</xref>
</contrib>
<contrib contrib-type="author"><name><surname>Gamble</surname>
<given-names>Carrol</given-names>
</name>
<xref ref-type="aff" rid="aff1"><sup>1</sup>
</xref>
</contrib>
<contrib contrib-type="author"><name><surname>Ghersi</surname>
<given-names>Davina</given-names>
</name>
<xref ref-type="aff" rid="aff11"><sup>11</sup>
</xref>
</contrib>
<contrib contrib-type="author"><name><surname>Ioannidis</surname>
<given-names>John P. A.</given-names>
</name>
<xref ref-type="aff" rid="aff12"><sup>12</sup>
</xref>
<xref ref-type="aff" rid="aff13"><sup>13</sup>
</xref>
</contrib>
<contrib contrib-type="author"><name><surname>Simes</surname>
<given-names>John</given-names>
</name>
<xref ref-type="aff" rid="aff14"><sup>14</sup>
</xref>
</contrib>
<contrib contrib-type="author"><name><surname>Williamson</surname>
<given-names>Paula R.</given-names>
</name>
<xref ref-type="aff" rid="aff1"><sup>1</sup>
</xref>
</contrib>
</contrib-group>
<aff id="aff1"><label>1</label>
<addr-line>Centre for Medical Statistics and Health Evaluation, University of Liverpool, Liverpool, United Kingdom</addr-line>
</aff>
<aff id="aff2"><label>2</label>
<addr-line>Centre for Statistics in Medicine, University of Oxford, Oxford, United Kingdom</addr-line>
</aff>
<aff id="aff3"><label>3</label>
<addr-line>Clinical Pharmacology Unit, UASP Hospital Clínic, Barcelona, Spain</addr-line>
</aff>
<aff id="aff4"><label>4</label>
<addr-line>Moorfields Eye Hospital, London, United Kingdom</addr-line>
</aff>
<aff id="aff5"><label>5</label>
<addr-line>Randomized Controlled Trials Unit, Canadian Institutes of Health Research, Ottawa, Canada</addr-line>
</aff>
<aff id="aff6"><label>6</label>
<addr-line>Healthier Communities/Public Health, Greenwich Council, London, England</addr-line>
</aff>
<aff id="aff7"><label>7</label>
<addr-line>Clinical Epidemiology Unit, DIM-Hospices Civils de Lyon, Lyon, France</addr-line>
</aff>
<aff id="aff8"><label>8</label>
<addr-line>Department of HIV/GUM, King's College London, London, United Kingdom</addr-line>
</aff>
<aff id="aff9"><label>9</label>
<addr-line>Institute of Social and Preventive Medicine, University of Bern, Bern, Switzerland</addr-line>
</aff>
<aff id="aff10"><label>10</label>
<addr-line>German Cochrane Centre, Department of Medical Biometry and Medical Informatics, University Medical Centre Freiburg, Freiburg, Germany</addr-line>
</aff>
<aff id="aff11"><label>11</label>
<addr-line>NHMRC Clinical Trials Centre, Camperdown, Australia</addr-line>
</aff>
<aff id="aff12"><label>12</label>
<addr-line>Department of Hygiene and Epidemiology, University of Ioannina School of Medicine, Ioannina, Greece</addr-line>
</aff>
<aff id="aff13"><label>13</label>
<addr-line>Institute for Clinical Research and Health Policy Studies, Department of Medicine, Tufts Medical Center, Tufts University School of Medicine, Boston, Massachusetts, United States of America</addr-line>
</aff>
<aff id="aff14"><label>14</label>
<addr-line>National Health and Medical Research Council (NHMRC) Clinical Trials Centre, University of Sydney, Sydney, Australia</addr-line>
</aff>
<contrib-group><contrib contrib-type="editor"><name><surname>Siegfried</surname>
<given-names>Nandi</given-names>
</name>
<role>Editor</role>
<xref ref-type="aff" rid="edit1"></xref>
</contrib>
</contrib-group>
<aff id="edit1">Medical Research Council South Africa, South Africa</aff>
<author-notes><corresp id="cor1">* E-mail: <email>kerry.dwan@liverpool.ac.uk</email>
</corresp>
<fn fn-type="con"><p>Conceived and designed the experiments: KD DGA CG PW. Performed the experiments: KD. Analyzed the data: KD. Contributed reagents/materials/analysis tools: JAA JB AWC EC ED PE EvE CG DG JPAI JS PW. Wrote the paper: KD DGA. Performed the literature search and data extraction, contacted all authors of included studies and wrote the first draft: KD. Contributed to the development of the protocol: KD DGA CG PW. Provided comments on the manuscript: DGA ED EvE CG JPAI JS PW. Gave permission to include data from their study in the review, responded to queries and provided extra information when needed and available: JAA JB AWC EC ED PE EvE DG JPAI.</p>
</fn>
</author-notes>
<pub-date pub-type="collection"><year>2008</year>
</pub-date>
<pub-date pub-type="epub"><day>28</day>
<month>8</month>
<year>2008</year>
</pub-date>
<volume>3</volume>
<issue>8</issue>
<elocation-id>e3081</elocation-id>
<history><date date-type="received"><day>7</day>
<month>12</month>
<year>2007</year>
</date>
<date date-type="accepted"><day>20</day>
<month>6</month>
<year>2008</year>
</date>
</history>
<copyright-statement>Dwan et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.</copyright-statement>
<copyright-year>2008</copyright-year>
<abstract><sec><title>Background</title>
<p>The increased use of meta-analysis in systematic reviews of healthcare interventions has highlighted several types of bias that can arise during the completion of a randomised controlled trial. Study publication bias has been recognised as a potential threat to the validity of meta-analysis and can make the readily available evidence unreliable for decision making. Until recently, outcome reporting bias has received less attention.</p>
</sec>
<sec><title>Methodology/Principal Findings</title>
<p>We review and summarise the evidence from a series of cohort studies that have assessed study publication bias and outcome reporting bias in randomised controlled trials. Sixteen studies were eligible of which only two followed the cohort all the way through from protocol approval to information regarding publication of outcomes. Eleven of the studies investigated study publication bias and five investigated outcome reporting bias. Three studies have found that statistically significant outcomes had a higher odds of being fully reported compared to non-significant outcomes (range of odds ratios: 2.2 to 4.7). In comparing trial publications to protocols, we found that 40–62% of studies had at least one primary outcome that was changed, introduced, or omitted. We decided not to undertake meta-analysis due to the differences between studies.</p>
</sec>
<sec><title>Conclusions</title>
<p>Recent work provides direct empirical evidence for the existence of study publication bias and outcome reporting bias. There is strong evidence of an association between significant results and publication; studies that report positive or significant results are more likely to be published and outcomes that are statistically significant have higher odds of being fully reported. Publications have been found to be inconsistent with their protocols. Researchers need to be aware of the problems of both types of bias and efforts should be concentrated on improving the reporting of trials.</p>
</sec>
</abstract>
<counts><page-count count="31"></page-count>
</counts>
</article-meta>
</front>
</pmc>
<affiliations><list><country><li>Allemagne</li>
<li>Australie</li>
<li>Canada</li>
<li>Espagne</li>
<li>France</li>
<li>Grèce</li>
<li>Royaume-Uni</li>
<li>Suisse</li>
<li>États-Unis</li>
</country>
<region><li>Angleterre</li>
<li>Auvergne-Rhône-Alpes</li>
<li>Bade-Wurtemberg</li>
<li>Canton de Berne</li>
<li>Catalogne</li>
<li>District de Fribourg-en-Brisgau</li>
<li>Grand Londres</li>
<li>Massachusetts</li>
<li>Nouvelle-Galles du Sud</li>
<li>Oxfordshire</li>
<li>Rhône-Alpes</li>
</region>
<settlement><li>Barcelone</li>
<li>Berne</li>
<li>Fribourg-en-Brisgau</li>
<li>Londres</li>
<li>Lyon</li>
<li>Oxford</li>
<li>Sydney</li>
</settlement>
<orgName><li>Université d'Oxford</li>
<li>Université de Berne</li>
<li>Université de Sydney</li>
</orgName>
</list>
<tree><country name="Royaume-Uni"><noRegion><name sortKey="Dwan, Kerry" sort="Dwan, Kerry" uniqKey="Dwan K" first="Kerry" last="Dwan">Kerry Dwan</name>
</noRegion>
<name sortKey="Altman, Douglas G" sort="Altman, Douglas G" uniqKey="Altman D" first="Douglas G." last="Altman">Douglas G. Altman</name>
<name sortKey="Bloom, Jill" sort="Bloom, Jill" uniqKey="Bloom J" first="Jill" last="Bloom">Jill Bloom</name>
<name sortKey="Cronin, Eugenia" sort="Cronin, Eugenia" uniqKey="Cronin E" first="Eugenia" last="Cronin">Eugenia Cronin</name>
<name sortKey="Easterbrook, Philippa J" sort="Easterbrook, Philippa J" uniqKey="Easterbrook P" first="Philippa J." last="Easterbrook">Philippa J. Easterbrook</name>
<name sortKey="Gamble, Carrol" sort="Gamble, Carrol" uniqKey="Gamble C" first="Carrol" last="Gamble">Carrol Gamble</name>
<name sortKey="Williamson, Paula R" sort="Williamson, Paula R" uniqKey="Williamson P" first="Paula R." last="Williamson">Paula R. Williamson</name>
</country>
<country name="Espagne"><region name="Catalogne"><name sortKey="Arnaiz, Juan A" sort="Arnaiz, Juan A" uniqKey="Arnaiz J" first="Juan A." last="Arnaiz">Juan A. Arnaiz</name>
</region>
</country>
<country name="Canada"><noRegion><name sortKey="Chan, An Wen" sort="Chan, An Wen" uniqKey="Chan A" first="An-Wen" last="Chan">An-Wen Chan</name>
</noRegion>
</country>
<country name="France"><region name="Auvergne-Rhône-Alpes"><name sortKey="Decullier, Evelyne" sort="Decullier, Evelyne" uniqKey="Decullier E" first="Evelyne" last="Decullier">Evelyne Decullier</name>
</region>
</country>
<country name="Suisse"><region name="Canton de Berne"><name sortKey="Von Elm, Erik" sort="Von Elm, Erik" uniqKey="Von Elm E" first="Erik" last="Von Elm">Erik Von Elm</name>
</region>
</country>
<country name="Allemagne"><region name="Bade-Wurtemberg"><name sortKey="Von Elm, Erik" sort="Von Elm, Erik" uniqKey="Von Elm E" first="Erik" last="Von Elm">Erik Von Elm</name>
</region>
</country>
<country name="Australie"><noRegion><name sortKey="Ghersi, Davina" sort="Ghersi, Davina" uniqKey="Ghersi D" first="Davina" last="Ghersi">Davina Ghersi</name>
</noRegion>
<name sortKey="Simes, John" sort="Simes, John" uniqKey="Simes J" first="John" last="Simes">John Simes</name>
</country>
<country name="Grèce"><noRegion><name sortKey="Ioannidis, John P A" sort="Ioannidis, John P A" uniqKey="Ioannidis J" first="John P. A." last="Ioannidis">John P. A. Ioannidis</name>
</noRegion>
</country>
<country name="États-Unis"><region name="Massachusetts"><name sortKey="Ioannidis, John P A" sort="Ioannidis, John P A" uniqKey="Ioannidis J" first="John P. A." last="Ioannidis">John P. A. Ioannidis</name>
</region>
</country>
</tree>
</affiliations>
</record>
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