Can authorship bias be detected in meta-analysis?

  • Ahmed M. Abou-SettaEmail author
  • Rasheda Rabbani
  • Lisa M. Lix
  • Alexis F. Turgeon
  • Brett L. Houston
  • Dean A. Fergusson
  • Ryan Zarychanski
Reports of Original Investigations



Statistical approaches have been developed to detect bias in individual trials, but guidance on how to detect systematic differences at a meta-analytical level is lacking. In this paper, we elucidate whether author bias can be detected in a cohort of randomized trials included in a meta-analysis.


We utilized mortality data from 35 trials (10,880 patients) included in our previously published meta-analysis. First, we linked each author with their trial (or trials). Then we calculated author-specific odds ratios using univariate cross table methods. Finally, we tested the effect of authorship by comparing each author’s estimated odds ratio with all other pooled estimated odds ratios using meta-regression.


The median number of investigators named as authors on the primary trial reports was six (interquartile range: 5-8, range: 2-32). The results showed that the slope of author effect for mortality ranged from − 1.35 to 0.71. We identified only one author team showing a marginally significant effect (− 0.39; 95% confidence interval, − 0.78 to 0.00). This author team has a history of retractions due to data manipulations and ethical violations.


When combining trial-level data to produce a pooled effect estimate, investigators must consider sources of potential bias. Our results suggest that systematic errors can be detected using meta-regression, although further research is needed to examine the sensitivity of this model. Systematic reviewers will benefit from the availability of methods to guard against the dissemination of results with the potential to mislead decision-making.

Les biais liés aux auteurs peuvent-ils être détectés dans une méta-analyse?



Des approches statistiques ont été élaborées pour détecter les biais dans les essais individuels, mais nous manquons d’orientations sur les méthodes à utiliser pour les détecter au niveau des méta-analyses. Dans cet article, nous étudions s’il est possible de détecter des biais liés à l’auteur dans un ensemble d’essais randomisés inclus dans une méta-analyse.


Nous avons utilisé les données sur la mortalité tirées de 35 essais (10 880 patients) inclus dans notre méta-analyse publiée antérieurement. Nous avons tout d’abord lié chaque auteur à son étude (ou à ses études). Nous avons ensuite calculé des rapports de cotes (odds ratios) spécifiques utilisant des méthodes de tableaux unifactoriels croisés. Enfin, nous avons testé l’effet « auteur » en comparant les rapports de cotes estimés de chaque auteur avec le rapport de cotes groupé de tous les autres auteurs au moyen d’une métarégression.


Le nombre médian d’investigateurs cité comme auteurs dans les publications principales des essais était de six (plage interquartile : 5 à 8, limites : 2 à 32). Les résultats ont montré que la pente de l’effet « auteur » pour la mortalité allait de -1,35 à 0,71. Nous n’avons identifié qu’une seule équipe d’auteurs ayant un effet peu à la limite de la significativité (-0,39; intervalle de confiance à 95 % : -0,78 à 0,00). Cette équipe a un historique de rétractions de publications en raison de manipulations des données et de violations de l’éthique.


Lorsqu’ils combinent les données des essais pour produire une estimation groupée de l’effet, les investigateurs doivent envisager les sources de biais potentiels. Nos résultats suggèrent que des erreurs systématiques peuvent être détectées en utilisant une métarégression bien qu’il soit nécessaire de poursuivre les recherches pour évaluer la sensibilité de ce modèle. Les réviseurs systématiques tireront parti de la disponibilité de méthodes les protégeant de la dissémination de résultats susceptibles de fausser des prises de décision potentielles.



Ryan Zarychanski and Alexis F. Turgeon receive salary support and operating funds from the Canadian Institutes of Health Research (CIHR). Lisa Lix is supported by a Manitoba Research Chair from Research Manitoba and a Foundation Scheme grant from CIHR. These funding agencies had no role in the design or conduct of the study, including but not limited to, study identification, collection, management, analysis, and interpretation of the data, or preparation, review, or approval of the final report.

Conflicts of interest

None declared.

Editorial responsibility

This submission was handled by Dr. Gregory L. Bryson, Deputy Editor-in-Chief, Canadian Journal of Anesthesia.

Author contributions

Ahmed Abou-Setta, Rasheda Rabbani, Lisa Lix, and Ryan Zarychanski contributed substantially to all aspects of this manuscript, including study conception and design; acquisition, analysis, and interpretation of data; and drafting the article. Alexis Turgeon, Brett Houston, and Dean Fergusson contributed substantially to the interpretation of data.


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Copyright information

© Canadian Anesthesiologists' Society 2019

Authors and Affiliations

  1. 1.George and Fay Yee Centre for Healthcare InnovationUniversity of Manitoba/Winnipeg Regional Health AuthorityWinnipegCanada
  2. 2.Department of Community Health Sciences, Max Rady College of Medicine, Rady Faculty of Health SciencesUniversity of ManitobaWinnipegCanada
  3. 3.Division of Critical Care Medicine, Department of Anesthesiology and Critical Care MedicineCentre de recherche CHU de Québec - Université Laval, Population Health and Optimal Health Practice Research Unit, Université LavalQuébec CityCanada
  4. 4.Department of Internal Medicine, Max Rady College of Medicine, Rady Faculty of Health SciencesUniversity of ManitobaWinnipegCanada
  5. 5.Clinical Epidemiology Program, Department of Medicine, Ottawa Hospital Research InstituteUniversity of OttawaOttawaCanada

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