Freeloading in biomedical research

  • M. P. RozingEmail author
  • T. N. van Leeuwen
  • P. H. Reitsma
  • F. R. Rosendaal
  • N. A. Aziz


The surge in the number of authors per article in the biomedical field makes it difficult to quantify the contribution of individual authors. Conventional citation metrics are typically based on the number of publications and the number of citations generated by a scientist, thereby disregarding the contribution of co-authors. Previously we developed the p-index that estimates the dependency of a scientist on co-authors during their career. In this study we aimed to evaluate the ability of the p-index to identify researchers with a relatively high degree of scientific dependence on co-authors. For this purpose, we retrieved articles, which were rejected for publication in Journal of Thrombosis and Haemostasis and subsequently published elsewhere. Assuming that authors who were added to a later version of these articles would not fulfill the full authorship criteria, we tested whether these authors showed a larger dependency on co-authors during their scientific career as would be evident from a higher p-index. In accordance with this hypothesis, authors who were added on later versions of articles showed a higher p-index than their peers, indicating an enduring pattern of dependency on other co-authors for publishing their work. This study underscores that questionable authorship practices are endemic to the biomedical research, which calls for alternative methods to evaluate a scientist’s qualities.


Citation metric Authorship p-Index 



The authors would like to thank Professor Lex Bouter, VUmc, for fruitful discussions relating to this manuscript. The authors are also extremely grateful for the indispensable help and assistance by Ms Fee Johnstone and Ms Sofija Gugina (Managing Editors of the Journal of Thrombosis and Hemostasis). NAA was supported by a VENI-grant (#91615080) from the Netherlands Organization of Scientific Research and a Marie Sklodowska-Curie Individual Fellowship grant from the European Union (Horizon 2020, #701130).

Compliance with ethical standards

Conflict of interest

The authors report no conflicts of interest.


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Copyright information

© Akadémiai Kiadó, Budapest, Hungary 2019

Authors and Affiliations

  • M. P. Rozing
    • 1
    • 2
    • 3
    Email author
  • T. N. van Leeuwen
    • 4
  • P. H. Reitsma
    • 5
    • 6
  • F. R. Rosendaal
    • 7
  • N. A. Aziz
    • 7
    • 8
  1. 1.Department of Public Health, Section of EpidemiologyUniversity of CopenhagenCopenhagenDenmark
  2. 2.Center for Healthy AgingUniversity of CopenhagenCopenhagenDenmark
  3. 3.The Research Unit for General Practice and Section of General Practice, Department of Public HealthUniversity of CopenhagenCopenhagenDenmark
  4. 4.Centre for Science and Technology Studies (CWTS)Leiden UniversityLeidenThe Netherlands
  5. 5.Department of Thrombosis and HemostasisLeiden University Medical CenterLeidenThe Netherlands
  6. 6.Einthoven Laboratory for Experimental Vascular MedicineLeiden University Medical CenterLeidenThe Netherlands
  7. 7.Department of Clinical EpidemiologyLeiden University Medical CenterLeidenThe Netherlands
  8. 8.German Centre for Neurodegenerative Diseases (DZNE)BonnGermany

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