Agnes Dechartres, MD, PhD; Ignacio Atal, MSc; Carolina Riveros, MSc; Joerg Meerpohl, MD; Philippe Ravaud, MD, PhD
Acknowledgment: The authors thank David Tovey, editor in chief of the Cochrane Library, for agreeing to share data from Cochrane reviews; Javier Mayoral Campos, system administrator; the Cochrane Central Executive for preparing files; and all Cochrane reviewers who collected data. They also thank Elise Diard from INSERM U1153 for help with figures and Laura Smales for English revision of the manuscript.
Financial Support: The researchers did not receive any external funding. This work was internally funded by Cochrane France.
Disclosures: Dr. Meerpohl reports that he is a member of Cochrane and co-director of Cochrane Germany. Authors not named here have disclosed no conflicts of interest. Disclosures can also be viewed at www.acponline.org/authors/icmje/ConflictOfInterestForms.do?msNum=M18-1517.
Reproducible Research Statement:Study protocol: Available from Dr. Dechartres (e-mail, email@example.com). Statistical code and data set: See Methods. Additional information is available to academic researchers from Dr. Dechartres (e-mail, firstname.lastname@example.org).
Corresponding Author: Agnes Dechartres, MD, PhD, Département Biostatistique, Santé Publique et Information Médicale, Hôpitaux Universitaires Pitié Salpêtrière–Charles Foix, 47/83 Boulevard de l’Hôpital, 75013 Paris, France; e-mail, email@example.com.
Current Author Addresses: Dr. Dechartres: Département Biostatistique, Santé Publique et Information Médicale, AP-HP, Hôpitaux Universitaires Pitié Salpêtrière–Charles Foix, 47/83 Boulevard de l’Hôpital, 75013 Paris, France.
Mr. Atal: Cochrane France, Hôtel-Dieu, 1 Place du Parvis Notre Dame, 75004 Paris, France.
Ms. Riveros and Prof. Ravaud: Centre d’Epidémiologie Clinique, Hôtel-Dieu, 1 Place du Parvis Notre Dame, 75004 Paris, France.
Dr. Meerpohl: Institute for Evidence in Medicine (for Cochrane Germany Foundation), Medical Center–University of Freiburg, Breisacher Strasse 153, 79110 Freiburg, Germany.
Author Contributions: Conception and design: A. Dechartres, I. Atal, J. Meerpohl, P. Ravaud.
Analysis and interpretation of the data: A. Dechartres, I. Atal, J. Meerpohl, P. Ravaud.
Drafting of the article: A. Dechartres, P. Ravaud.
Critical revision of the article for important intellectual content: A. Dechartres, I. Atal, J. Meerpohl, P. Ravaud.
Final approval of the article: A. Dechartres, I. Atal, C. Riveros, J. Meerpohl, P. Ravaud.
Provision of study materials or patients: P. Ravaud.
Obtaining of funding: P. Ravaud.
Administrative, technical, or logistic support: I. Atal, P. Ravaud.
Collection and assembly of data: A. Dechartres, I. Atal, C. Riveros, P. Ravaud.
Evidence about the effect on meta-analysis results of including unpublished trials or those published in languages other than English is unclear or discordant.
To compare treatment effects between published and unpublished randomized controlled trials (RCTs) and between trials published in English and other languages using a meta-epidemiologic approach.
Cochrane reviews published between March 2011 and January 2017 and trial references cited in the reviews.
RCTs included in meta-analyses of 3 or more trials with a binary efficacy outcome.
Trial characteristics were extracted by original review authors. A single reviewer assessed publication status and language, with quality assurance by another investigator.
Among 5659 RCTs included in 698 meta-analyses, 5303 (93.7%) were published in journal articles and 356 (6.3%) were unpublished. Of journal articles, 92.6% (4910 of 5303) were published in English and 7.4% (393 of 5303) in another language. Treatment effects were larger in published than unpublished trials (combined ratio of odds ratios [ROR] for 174 meta-analyses, 0.90 [95% CI, 0.82 to 0.98]; I2 = 19.3%; τ2 = 0.0492). Treatment effects were also larger for trials published in a language other than English than in English (combined ROR for 147 meta-analyses, 0.86 [CI, 0.78 to 0.95]; I2 = 0%; τ2 = 0.0000).
Reliance on the primary reference cited by review authors as the record of interest.
In meta-analyses, treatment effects were larger in published than unpublished trials and, for published trials, in those published in a language other than English than in English.
Dechartres A, Atal I, Riveros C, et al. Association Between Publication Characteristics and Treatment Effect Estimates: A Meta-epidemiologic Study. Ann Intern Med. 2018;169:385–393. [Epub ahead of print 21 August 2018]. doi: https://doi.org/10.7326/M18-1517
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Published: Ann Intern Med. 2018;169(6):385-393.
Published at www.annals.org on 21 August 2018
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