Context To determine the prevalence of honorary and ghost authorship in Cochrane
reviews, how authorship is assigned, and the ways in which authors and Cochrane
editorial teams contribute.
Methods Using a Web-based, self-administered survey, corresponding authors for
577 reviews published in issues 1 and 2 from 1999 of The Cochrane Library
were invited to report on the prevalence of honorary and ghost authors, contributions
by authors listed in the byline and members of Cochrane editorial teams, and
identification of methods of assigning authorship. Responses were received
for 362 reviews (63% response rate), which contained 913 authors.
Results One hundred forty-one reviews (39%) had evidence of honorary authors,
32 (9%) had evidence of ghost authors (most commonly a member of the Cochrane
editorial team), and 9 (2%) had evidence of both honorary and ghost authors.
The editorial teams contributed in a wide variety of ways to 301 reviews (83%).
Authorship was decided by the group of authors (31%) or lead author (25%)
in most reviews. Authorship order was assigned according to contribution in
most reviews (76%). The 3 functions contributed to most by those listed in
the byline were assessing the quality of included studies (83%), interpreting
data (82%), and abstracting data from included studies (77%).
Conclusions A substantial proportion of reviews had evidence of honorary and ghost
authorship. The Cochrane editorial teams contributed to most Cochrane reviews.
Authorship in biomedical publications establishes accountability, responsibility,
and credit.1 A survey by Flanagin et al2 found that 26% of review articles in 6 peer-reviewed
medical journals contained evidence of honorary authorship (naming as an author
an individual who does not meet authorship criteria) and 10% of review articles
contained evidence of ghost authorship (failure to name as an author an individual
who has made substantial contributions that merited authorship or an unnamed
individual who participated in writing the article). Other studies3- 5 have confirmed that
a high proportion of authors listed in the byline do not fulfill criteria
The Cochrane Collaboration is an international organization that was
established to help individuals make well-informed decisions about health
care by preparing, maintaining, and ensuring the accessibility of systematic
reviews of the benefits and risks of health care interventions.6
Cochrane Collaborative Review Groups (CRGs) support authors worldwide in preparing
and maintaining systematic reviews according to a common methodologic framework.7 Other types of groups, devoted to methods, dimensions
of health care, consumer perspectives, and geographic regions, also contribute
to the Cochrane Collaboration's work. Cochrane Collaborative Review Groups
cover most of the major areas of health care and are coordinated by an editorial
team, which is composed of a CRG coordinator (who manages and supports a CRG
on a day-to-day basis), a trials search coordinator (who is responsible for
searching for studies that fall within the scope of the group and maintaining
their details in a specialized register), and a group of editors led by a
coordinating editor. The editorial teams edit and assemble completed reviews
for inclusion in The Cochrane Library, a collection of databases published
on CD-ROM and the Web and updated quarterly. Within The Cochrane Library,
Cochrane reviews are published in the Cochrane Database of Systematic Reviews.
A corresponding author is named for each review.
Because Cochrane reviews are published electronically, updated quarterly,
and dependent on assistance from CRGs, they may generate practices of authorship
and contributorship that differ from those generated by print articles. However,
little is known about these practices.
The objectives of this study were to determine the prevalence of honorary
and ghost authorship in Cochrane reviews, the ways in which authors and members
of CRG editorial teams contribute to Cochrane reviews, and the methods by
which authorship is assigned.
In March 2000, we invited the corresponding authors of the 577 Cochrane
reviews published in issues 1 and 2 from 1999 of The Cochrane Library to complete
a 29-item Web-based questionnaire. The questionnaire was piloted before the
launch of the survey and was based on one previously used by Flanagin et al2 in a study aimed at determining the prevalence of
honorary and ghost authors in peer-reviewed biomedical journals. We used the
software package SPSS version 9 (SPSS Inc, Chicago, Ill) to analyze the completed
Our criteria for authorship were based on recommendations of the International
Committee of Medical Journal Editors (ICMJE)8
in March 2000, when the survey was launched. Three conditions defined authorship:
(1) conceiving and designing the review or analyzing and interpreting the
data (we considered the following contributions, common to the conduct of
systematic reviews, to fulfill this criterion: conceived of or designed the
review, designed the literature search, conducted the literature search, screened
results of searches, assessed quality of included studies, abstracted data
from included studies, performed statistical analysis, interpreted data, contacted
authors of primary research or industry, or supervised the work of coauthors,
if any); (2) drafting the review or revising it to make important changes
in content; and (3) approving the final version before it was submitted to
the editorial base of the CRG through which it was to be published in The
Cochrane Library. Any author not meeting all 3 conditions was classified as
an honorary author.
We defined a ghost author as a person who, in the opinion of the corresponding
author, had made a contribution that merited authorship or who had assisted
in drafting the review but was not listed as an author or mentioned in the
acknowledgment section of the review. Corresponding authors were also asked
to indicate, from a list of functions, the support received from members of
the CRG editorial team (Table 1).
Corresponding authors for 362 of 577 reviews (63% response rate) completed
the questionnaire. Of these 362 reviews, 13% had a single author, 49% had
2 authors, 21% had 3 authors, 11% had 4 authors, and 6% had 5 or more authors.
In comparison, of the 215 reviews for which no response to the questionnaire
was received, 23% had a single author, 32% had 2 authors, 16% had 3 authors,
10% had 4 authors, and 19% had 5 or more authors.
The 362 reviews contained a total of 913 authors. Of the 913 authors,
18 (2%) did not participate in conceiving and designing the review or analyzing
and interpreting the data, 204 (22%) did not participate in drafting or revising
the review, and 168 (18%) did not participate in approving the review before
it was submitted. Of the 362 reviews, 141 (39%) had evidence of honorary authors.
Fourteen reviews (4%) contained at least 1 author who had not participated
in conception and design or conduct, 87 reviews (24%) contained at least 1
author who had not participated in drafting or revising the review, and 98
reviews (27%) contained at least 1 author who had not participated in approving
the review before it was submitted.
Authors listed in the byline contributed to a variety of functions (Table 1); the functions contributed to
most often were assessing the quality of included studies (83%), interpreting
data (82%), and abstracting data from included studies (77%).
Thirty-two reviews (9%) had evidence of ghost authors, although from
the information provided it was not possible to determine whether the contribution
of the ghost authors merited authorship or whether a mention in the acknowledgment
section would have sufficed. The CRG editorial team members were identified
as ghost authors in 22 reviews (6%). Other ghost authors identified in 10
reviews (3%) included named individuals, lay reviewers, peer reviewers, or
authors who had contributed to a previous version of the review but were not
involved in the current version. Nine reviews (2%) contained both honorary
and ghost authors.
Authorship was decided by the group of authors (31%) or lead author
(25%) in most reviews. There was no formal mechanism invoked for deciding
authorship in 28% of reviews. Authorship order was assigned according to contribution
in most reviews (76%) and alphabetically by author surname in 9 reviews (2%).
In 79 reviews (22%), a variety of other methods were used to assign authorship,
including seniority of those involved, senior author last, responsibility
for the work, internal discussion and agreement, and the stage at which the
authors became involved in the review. The CRG editorial teams contributed
to 301 reviews (83%) in a variety of ways (Table 1 lists specific functions).
Honorary authorship in Cochrane reviews was more prevalent than ghost
authorship. The main reasons for authors being classified as honorary authors
were that they had not participated in drafting or revising the review or
had not approved it for submission to the editorial base of the CRG. The prevalence
of honorary authorship in Cochrane reviews was greater than that reported
for review articles in peer-reviewed medical journals,2
although this may be at least partly explained by differences in the definition
of honorary authorship used in the 2 studies. The previous study used a less
strict definition of actual authorship, with an article defined as having
an honorary author if the corresponding author did not fulfill the ICMJE authorship
criteria, would not feel comfortable explaining the major conclusions of the
article or review, or reported that a coauthor performed only one function
and nothing else from a list of 17 activities, whereas in this study the authorship
criteria were applied equally to all authors.
In most reviews, the group of authors or lead author decided authorship,
and the order of authors was assigned according to the contribution they had
made. The CRG editorial teams made substantial contributions to most Cochrane
reviews, especially to conception and design, literature searches, and preparation
Our survey had limitations. The information was based on self-report
by the corresponding authors on behalf of their coauthors. Also, the response
rate to our survey was 63%, and we do not know if the reviews of nonrespondents
differed systematically from those of respondents in terms of the prevalence
of honorary or ghost authors or the ways in which authors and CRG editorial
teams contributed to the reviews.
The rate of ghost authorship may be greater than we found, since our
definition excluded the possibility that a person named in the acknowledgment
section of the review could have made a contribution that merited authorship.
Conversely, the rate could be an overestimate, since we included among ghost
authors those individuals who had contributed to a previous version of the
review but were not involved in the current version. Such persons should not
qualify for authorship if they do not contribute to the update of the review,
in the same way as authors who have not been involved in a follow-up of a
previously published trial do not qualify for authorship in the update, although
much of the material and text may be the same.
Steps have been taken by the Cochrane Collaboration to improve the reporting
of contributions to reviews. Since our survey was undertaken, a section in
Cochrane reviews has been created where the names and contributions of all
individuals who have contributed to a Cochrane review (including the editorial
team of the CRG) can be described. The Cochrane Reviewers
Handbook7 gives guidance on this, providing
a list of potential contributions adapted from Yank and Rennie.9
The Handbook7 now also recommends that authorship
criteria for Cochrane reviews should be based on the recommendations of the
ICMJE. Adherence to these recommendations should help reduce the prevalence
of honorary and ghost authorship and encourage transparency in the reporting
of contributions. The Cochrane Collaboration might also wish to consider implementing
a version of the disclosure policies already adopted by some journals,10 which require authors to describe their contributions
in their own words or to complete a checklist on authorship criteria and contributions.
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