Multiple authorship: growth or inflationary bubble?


Múltiple autoría: crecimiento o burbuja expandida



Kenneth Rochel de Camargo Jr.I; Claudia Medina CoeliII

IDepartamento de Planejamento e Administração em Saúde. Instituto de Medicina Social. Universidade do Estado do Rio de Janeiro. Rio de Janeiro, RJ, Brasil
IIInstituto de Estudos em Saúde Coletiva e Departamento de Medicina Preventiva. Faculdade de Medicina. Universidade Federal do Rio de Janeiro. Rio de Janeiro, RJ, Brasil





OBJECTIVE: To analyze the increase in number of authors per article in Brazilian scientific journals on public health.
METHODS: Articles published between 1999 and 2010 in six journals on public health and one medical journal (for comparison) from SciELO with Qualis (Capes) classification equal or superior to B-1, were searched on the LILACS database. The evolution of the median number of authors/article and the proportion of articles with more than four authors were evaluated. The association between the the triennium of publication and the presence of four or more authors per paper was estimated through the Mantel-Haenzel odds ratio, adjusted for the type of journal.
RESULTS: An increase of the median number of authors and the proportion of articles with more than four authors was observed in all journals, especially in the last triennium. The odds ratio for articles with four or more authors, adjusted for the type of journal, were: second triennium 1.3 (95%CI 1.1;1.4); third triennium 1.5 (95%CI 1.3;1.8), fourth triennium 2.39 (95%CI 2.1;2.8).
CONCLUSIONS: Scientific journals on public health have shown an increase in the number of authors per article over the years, regardless of editorial orientation.

Descriptors: Authorship. Journal Article. Public Health. Authorship and Co-Authorship in Scientific Publications. Scientific and Technical Publications. Scientific Publication Ethics.


OBJETIVO: Analizar el aumento del número de autores por artículo en revistas científicas brasileñas de salud colectiva.
MÉTODOS: Se investigaron en la base de datos LILACS artículos publicados en seis revistas de salud colectiva y una revista médica (para comparación), de la colección SciELO, con clasificación Qualis, de la Capes, igual o superior a B-1, entre 1999 y 2010. Se evaluaron la evolución de la mediana de números de autores/artículo y la proporción de artículos con más de cuatro autores. Se estimó la asociación entre el trienio de publicación y la presencia de cuatro o más autores por artículo por medio de odds ratios de Mantel-Haenzel, ajustados para el tipo de revista.
RESULTADOS: Hubo crecimiento de la mediana del número de autores y de la proporción de artículos con más de cuatro autores para todas las revistas, principalmente en el último trienio. Los odds ratios para publicación de artículos con cuatro autores o más, ajustados para el tipo de revista, fueron: segundo trienio: 1,3 (IC95% 1,1; ,4); tercero trienio: 1,5 (IC95% 1,3; ,8); cuarto trienio: 2,39 (IC95% 2,1; 2,8).
face="Verdana, Arial, Helvetica, sans-serif" size="2"> Periódicos científicos de salud colectiva han presentado aumento en el número de autores por artículo a lo largo de los años, independientemente de la orientación editorial.

Descriptores: Autoria. Artículo de Revista. Salud Pública. Autoría y Coautoría en la Publicación Científica. Publicaciones Científicas y Técnicas. Ética en la Publicación Científica.




The number of authors per article has increased in scientific journals, a peculiar worldwide phenomenon in recent decades. Studies using different techniques, involving diverse journal groups and varied reference periods have unequivocally verified this fact.1, 8,15,18,22 One of these studies24 quantified the authorship of millions of articles in five decades and showed that such phenomenon occurs in all areas of knowledge, including the social sciences, albeit with less intensity.

Most of these studies merely identify and describe the phenomenon, but there are those that seek to understand its determinants.2,5,12,17,23 Analysis performed on a sample of authors of 896 articles published in leading medical journals (Annals of Internal Medicine, JAMA, Lancet, Nature Medicine, New England Journal of Medicine and PLoS Medicine) showed a reasonable proportion (17.6%) of cases in which individuals who were included as authors had not contributed sufficiently to merit this designation, characterizing the so-called "honorary authorship". Considering only research articles, this proportion reached 25%.

One of the mentioned studies5 showed that the main contribution to the growing number of authors per article in the British Medical Journal (BMJ), over 20 years, was the relative increase in the number of senior authors. This finding becomes worrying in the view of the "white bull effect" (a reference to the myth of seduction of Europa by Zeus, disguised as a white bull), described by Kwok14 as the self-imposition of a given individual as "honorary author" to a researcher in a weaker position. For instance, the negotiation of senior researchers with students under their guidance. How much of the senior authors' contribution in the study on the BMJ articles would be attributable to the "white bull" is something that must be questioned.

A frequent explanation for the increase in the average number of authors is that the greater complexity of studies would demand more and more cooperative work.1,7,8,17 While this is possible and even probable, Papatheodorou et al17 disagree that this fact explains all the situations in which such an increase is observed. Their research showed an increase in the number of authors over the years, in both randomized and non-randomized studies, with the effect of year of publication remaining significant after adjustment for other factors, such as the topic of study, multinational study and population size.

One reason for the growing number of authors would be the answer to the pressures on researchers to increasingly publish articles (the so-called "publish or perish"). However, in some situations a large number of authors is justified, including multicenter and/or multidisciplinary studies, and research involving complex and laborious designs. Therefore, the analyses presented are justified to protect and adequately characterize these situations.

Such considerations led to the question: Would this growth also be observed in Brazilian journals on public health?

Hence, the objective of this study is to analyze the increasing number of authors per article in Brazilian scientific journals on public health.



A study was carried out in 2010 with Brazilian journals on public health included in the ScieLO collection, with classification Qualis/CAPES equal or superior than B1: Revista de Saúde Pública (RSP), Cadernos de Saúde Pública (CSP), Ciência & Saúde Coletiva (C&SC), Revista Brasileira de Epidemiologia (RBE), Physis e Interface. The Brazilian Journal of Medical and Biological Research (BJMBR), also holding a Qualis B1 classification in public healthª (2010) and found in SciELO, was included for comparison. For each journal, all references in the LILACS database (1999 to 2010) were selected. The initial year of the period was chosen for the journals that were already being published for at least one year, and 2010 represented the last year with all issues published and present in the database at the time of the review.

The references were exported in RIS format and the number of authors per paper was calculated by an application developed for this purpose. Analyses were performed according to the four triennia of the studied period to ensure a greater stability in the estimates. The median number of authors per article (interquartile range) and the proportion of the number of articles with four or more authors were calculated for each triennium. The association between the triennium of publication and the presence of four or more authors per paper was estimated through the Mantel-Haenzel odds ratio, adjusted for the type of journal. The journals were grouped into four categories3: 1) clinical journal (BJMBR); 2) journals with a higher proportion of epidemiological articles (RBE, CSC, RSP); 3) journal without a clear predominance of a specific study field (C&SC); 4) journals with a higher proportion of articles on the humanities (Physis and Interface). The analyses were performed with the Stata program (version 9.0).



A higher median of authors for the BJMBR, followed by group 2 journals (RBE, CSC, RSP), was observed in all periods (Table 1). Group 4 (Physis and Interface) and group 3 (C&SC) journals had the lowest medians. An increase in the median number of authors in the last triennium was observed for all journals, when compared to the first triennium. The proportion of articles with four or more authors had a roughly similar distribution to the median of authors related to journal category, although C&SC has shown higher proportions than the group 4 journals for this indicator (Figure 1). The growth of this proportion was observed for all journals analyzed. Taking the first triennium as a reference, the odds ratios are presented for articles with four or more authors, adjusted according to journal group (Table 2). This analysis also reveals growth. The chance of having four or more authors was 2.39 higher for articles published in the last three years compared to those published in the first three years (Table 2).



An increase in the number of authors per paper was observed, particularly in the last triennium, based on two indicators: median number of articles and proportion of articles with four or more authors.

As this phenomenon is confirmed in the analyzed journals, a question remains: Is it the result of an increased cooperation between Brazilian authors or "honorary authorship"?

The possibility of undue authorship has taken various editors to express their views over time.9-11,19,21 An editorial published in Nature9 reports the difficulty of finding mechanisms to control the situation. Another10 connects this problem with the use of quantitative indicators of scientific production, as the productivity incentive would lead to the proliferation of authors as a way to cheat the system, at least partially.

A particularly intense exchange began after a joint editorial by the then editors of Lancet and BMJ11 (Richard Horton and Richard Smith, respectively), who analyzed their concerns regarding this problem, and announced a seminar to discuss proposals to address the situation. An editorial in the BMJ19 points to a radical strategy, based on the discussions from the seminar previously mentioned: articles would have contributors instead of authors, who would be identified according to their participation, just as in the credits of a movie. To ensure ethical responsibility on the printed content, the articles would have a "guarantor". These ideas prompted the then editor of the American Journal of Public Health (AJPH), Mervyn Susser, to publish an editorial21 that endorsed such proposal, asking the readers for their opinions. Responses were published in the May 1998 issue, occupying practically the entire letters section of the AJPH. The positions were varied, and no consensus was reached.

Publications4,6,7,16,20 make revisions of proposed solutions, trying to offer control models to limit the possibility of undue authorship. Such solutions are divided into two major groups, both based on exhaustive lists of possible actions (contributions) in the making of an article. The first treats the list as a checklist, requiring minimum number of contributions (usually three) for the authorship to be considered. The other works with complex score systems assigned to each type of contribution, requiring a minimum total value, which varies according to the scheme adopted. One of the consulted papers13 sought to evaluate the operation of such schemes. The authors of 181 articles published in the Croatian Medical Journal, from January to July 2005, were consulted, by randomly using instruments based on the checklist or scoring system. It was concluded that the latter was more sensitive for determining authorship.

These proposals are attempts to implement the minimum requirements for authorship by the International Committee of Medical Journal Editors (ICMJE),b which states that "authorship credit should be based on 1) substantial contributions towards the conception and design, data acquisition, or analysis and interpretation of data; 2) article writing or critical revision with important intellectual content; and 3) final approval of the version to be published. Authors should meet conditions 1, 2 and 3." This guidance resulted from the discovery of a fraud case (known as "Darsee affair") in the 1980s, which exposed several cases of "honorary authorship".19

One review article analyzed16 points out to usual and mistaken roles for attributing authorship, such as being administratively in charge of a research group or department, and raising funds for a project without being involved with it otherwise. In addition, there are other roles that could be acknowledged, but no authorship would be given to those revising or editing a manuscript, performing manual data collection (exceptional circumstances could change this), cleaning data, as well as providing resources (e.g. reagents or basic processes involved in the research that have not been specifically developed for it), basic maintenance and management of equipment/instruments (equipment/tools developed specifically for the considered project could, nonetheless, qualify for authorship). The studied journals adopt the ICMJE criteria with small systematic variations, demanding the authors a statement of authorship responsibility, without presenting any kind of checklist or score.

The CNPq itself recently reported problems in the dissemination of scientific research under its funding. Considering that overcoming such problems would require the formulation of specific internal rules, nonexistent at that time, a committee responsible for their elaboration was created. Their publication on the organization's website followed.c Several rules relate to the question of authorship (referring to the ICMJE criteria), indicating that, at least, there is some concern over this issue in our circles.

We emphasize that there are multiple authors per article, and even though the average number of authors is growing, it does not translates as an irregularity. The scientific work becomes more complex with the development of major projects. In health sciences, and particularly in public health, increasingly large databases are created, requiring more sophisticated strategies for extracting relevant information, or able to articulate diverse data and/or material sources (biobanks, collections of genetic profiles). Therefore, the appearance of larger research teams is inevitable, and this will tension the definition of what exactly qualifies for authorship. The growing complexity of research, with multiple insertion possibilities, even without undue manipulation, creates difficulties in defining who can appear as an author in a given publication, and this is not adequately discussed by Brazilian authors and editors.

It is not possible to determine, due to the limitations of this study, whether or not the honorary authorship was occurring in the publications analyzed. The increasing number of authors per article, regardless of the journal's editorial orientation, indicates the need to further explore this issue through more extensive studies that include other variables, allow to qualify more precisely the type of study that originated the article and also assess authorship qualitatively.

Particularly in the absence of effective controls, the attribution of "honorary authorship" may be a considerable temptation in an environment which stimulates the production of increasing numbers of articles. It is a task for editors, authors and readers to ensure compliance with the ethical principles governing authorship, thus avoiding the situation when the basic currency of academic credibility will suffer from inflationary devaluation, as expressed by Papatheodorou et al.17 These authors made a clear allusion to what repeatedly occurred in recent decades with certain products under accelerated growth: the collapse of their markets, showing that their apparent value was unreal, an inflationary bubble.



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6. Dulhunty JM, Boots RJ, Paratz JD, Lipman J. Determining authorship in multicenter trials: a systematic review. Acta Anaesthesiol Scand. 2011;55(9):1037-43. DOI:10.1111/j.1399-6576.2011.02477.x        

7. Eggert LD. Best practices for allocating appropriate credit and responsibility to authors of multi-authored articles. Front Psychol. 2011;2:196. DOI:10.3389/fpsyg.2011.00196        

8. Epstein RJ. Six authors in search of a citation: villains or victims of the Vancouver convention? BMJ. 1993;306(6880):765-7.         

9. Games people play with authors' names. Nature. 1997;387(6636):831. DOI:10.1038/43001        

10. Greene M. The demise of the lone author. Nature. 2007;450(7173):1165. DOI:10.1038/4501165a        

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14. Kwok LS. The White Bull effect: abusive coauthorship and publication parasitism. J Med Ethics. 2005;(9):554-6. DOI:10.1136/jme.2004.010553        

15. Levsky ME, Rosin A, Coon TP, Enslow WL, Miller MA. A descriptive analysis of authorship within medical journals, 1995-2005. South Med J. 2007;100(4):371-5. DOI:10.1097/01.smj.0000257537.51929.4b        

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19. Smith R. Authorship: time for a paradigm shift? [editorial]. BMJ. 1997;314(7086):5.         

20. Strange K. Authorship: why not just toss a coin? Am J Physiol Cell Physiol. 2008;295(3):C567-75. DOI:10.1152/ajpcell.00208.2008        

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22. Weeks WB, Wallace AE, Kimberly BCS. Changes in authorship patterns in prestigious US medical journals. Soc Sci Med. 2004;59(9):1949-54. DOI:10.1016/j.socscimed.2004.02.029        

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24. Wuchty S, Jones BF, Uzzi B. The increasing dominance of teams in production of knowledge. Science. 2007;316(5827):1036-9. DOI:10.1126/science.1136099        



Kenneth Rochel de Camargo Jr.
R. São Francisco Xavier, 524, 7º andar
Bloco D 20559-900
Rio de Janeiro, RJ, Brasil
Email: kenneth@uerj.br

Receveid: 1/2/2012
Approved: 4/23/2012



The authors declare that there are no conflicts of interest.
a For purposes of evaluation of postgraduate programs, the Brazilian Ministry of Education created a ranking of journals based on different criteria and specifi c to each area of knowledge. Further information at http://www.capes.gov.br/avaliacao/qualis
b International Committee of Medical Journals Editors. Uniform requirements for manuscripts submitted to journals: updated April 2010. [cited 2011 Dec 28]. Available from: http://www.icmje.org/urm_main.html
c Ministério da Ciência e Tecnologia, Conselho Nacional de Desenvolvimento Científi co e Tecnológico. Normas: ética e integridade na prática
científi ca: relatório da Comissão de Integridade do CNPQ [cited 2012 Aug 11]. Available from: http://www.cnpq.br/normas/lei_po_085_11.htm#etica http://www.cnpq.br/documents/10157/a8927840-2b8f-43b9-8962-5a2ccfa74dda

Faculdade de Saúde Pública da Universidade de São Paulo São Paulo - SP - Brazil
E-mail: revsp@org.usp.br