Repetitive, Duplicate, and Redundant Publications: A Review for Authors and Readers

Trying to Define the Problem 

It would seem that the topic of duplicate publication is easy to characterize. However, defining this issue is challenging because of the many varieties in which one can slice, reformat, or reproduce material from a study. This issue also goes beyond the duplication of a single study because it is possible that the same or similar data can be published in the early, middle, and late stages of an ongoing study. This can have a damaging impact on the scientific literature base.

Similar to slicing a cake, there are many ways of representing a study or a set of data. One can slice a cake into squares, triangles, rounds, or layers. Which of these is the best way to slice a cake? Unfortunately, this is exactly the wrong question. The point is that the cake that is being referred to, the data set or the study, should not be sliced at all. Instead, the study should be presented as a whole to the readership to ensure the integrity of science and, most importantly, because of the impact it may have on patients who will be affected by the information contained in the literature.1

One of the landmark events relating to duplicate publication is the publication of the 1969 editorial in the New England Journal of Medicine by Franz Joseph Ingelfinger. Now known for the Ingelfinger rule, he proposed that manuscripts should only be considered for publication in his journal if they were not submitted or published elsewhere.2 Since that time, many journals have adopted the same policy. However, there are some who suggest that the evolving publications environment may change the way we address these issues, including the Ingelfinger rule.3, 4

Redundant, duplicate, or repetitive publications occur when there is representation of 2 or more studies, data sets, or publications5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15 in either electronic or print media.7, 15 The publications may overlap partially or completely, such that a similar portion, major component(s), or complete representation of a previously/simultaneously or future published study is duplicated. These publications may share the same, similar, or overlapping data, hypotheses, discussion, methods, results, and/or conclusions.6, 8, 9 Typically, one or more of the publications do not have full cross-references to others5, 8, 15 and may have similar or identical authors in various orders.11, 12 In some cases, redundancy may include salami slicing of the data into subsets instead of representing the study as a whole (eg, using data collected from one group of patients but carving out different data subsets instead of appropriately combining them into 1 study), or the authors may add new data and make a study appear new.1, 6, 9, 10, 11

Bailey16 and von Elm et al17 used classification systems to analyze the practices of duplicate publication in their respective fields. Each method offers an interesting insight on the variations and intricacies of duplicate publication. Bailey16 separated his classification system of similarity into 5 levels: level I, 10% or more of the contents are identical; level II, highly similar contents without exact duplication; level III, subsets (salami slicing) of the same study; level IV, number of subjects in the study increases without new conclusions or changes in the intervention; and level V, the same message is published for different readerships. von Elm et al17 produced an algorithm with 6 endpoints to categorize various patterns of duplicate publications: pattern 1A, identical study sample and identical outcomes; pattern 1B, identical study sample and identical outcomes but 2 or more articles are combined to produce a different article; pattern 2, identical study sample but different outcomes; pattern 3A, different study samples with new data added to a preliminary article with similar outcomes; pattern 3B, different study samples with similar outcomes, part of a larger trial published in separate pieces; and pattern 4, duplication with different study samples and different outcomes. Upon review of these classification systems, it is evident that duplicate publication is a complex issue.

What Is Wrong With Duplicate Publication? 

Duplicate/redundant publication is especially improper when it is deceptive. Covert submission and publication of previously published material are deceiving to those who read or use the information contained in the article.

Most would agree that if the editors, peer reviewers, readers, and all end users of the information were informed about an overlap or duplication of publication, appropriate decisions could be made. However, when authors do not disclose that the same study sample is being used or that an earlier study is being supplemented to produce a larger sample size although the earlier study included the same patients, they would be misleading the readership, and some would consider such act as a form of ethical misconduct. Redundant publication not only has ethical and legal issues but also wastes resources and has a negative impact on the literature base (Fig 1).

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Fig 1. Problems caused by duplicate publication.

Why Do People Do It? 

There are many proposed reasons for why authors engage in the act of covert or overt duplicate publication. Ultimately, the quandary lies in whether an author fully discloses to the editor that there is a potential that the submitted article contains some or much of the data from another study (unpublished or not). Such redundancy should be divulged to the readership by including a disclosure in the text of the article. Table 1 cites some reasons for duplicate publication.

Table 1. Several reasons prompting duplicate publication

	Considered as noble reasons	Considered as questionable or inappropriate reasons	Considered as reasons caused by ignorance
	To reach a larger audience9, 11	To inflate publication bibliography on grant applications6, 11	Some authors are not aware that duplicate/redundant publications are inappropriate or exemplify ethical misconduct1, 19
	To report study findings to the media15	To increase publication record listed on curriculum vitae6, 9	During the request for revision, some editors recommend removing content or publishing an article as 2 studies; thus, although editors may not be suggesting to republish the data, authors may misunderstand and think that this is being condoned and hence publish out of ignorance1
		To secure a patent or financial interest6
		To influence promotion of rank6, 10
		To influence decisions from funding agencies6, 10

It is important to note that although authors have published a body of text, they are not allowed to republish either portions or the whole of their work. As stated in the World Association of Medical Editors guidelines, “[s]elf-plagiarism refers to the practice of an author using portions of their previous writings on the same topic in another of their publications, without specifically citing it formally in quotes…this usually violates the copyright that has been assigned to the publisher…”5

When Is Duplicate Publication Acceptable? 

There are few instances when republication is acceptable; all of these include proper disclosure to all involved (eg, editor, readers).1 Fig 2 lists some instances when this may be appropriate.

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Fig 2. Situations when duplicate publication may be acceptable.

In each case, full disclosure and agreement are necessary. The International Council of Medical Journal Editors has published several criteria necessary if repetitive, redundant, or duplicate publication is acceptable. These conditions include the following: (1) editors from both journals have given the author(s) approval; (2) priority of the primary publication is respected; (3) the secondary publication, which may be an abbreviated version, is intended for a different readership; (4) the secondary publication accurately represents the primary publication; (5) the secondary publication clearly states that it is based on or replicates the primary publication; and (6) the title of the secondary publication indicates that it is a secondary publication.7

Who Is Responsible? 

Embedded in the definition of authorship is the fact that authors are ultimately the ones responsible for presenting, publishing, and defending their work. Therefore, the ultimate burden of integrity falls upon the authors. Although some authors may claim ignorance to publication guidelines, many journals clearly publish what is or is not acceptable with regard to duplicate publication. Thus, authors must read the journal instructions and must be aware of these issues.16, 18 As Tobin10 stated, “[t]he editor is not the police, it is ultimately the authors who are responsible.”

Editors have a different but equally tasking responsibility in relation to duplicate publication. Editors must clearly define and implement the ethical standards of their journals.21 Although editors are responsible for following up on ethical misconduct issues when they come to light, they are not solely responsible for investigating and/or punishing the authors. The structure of the greater scientific community, including authors' institutions, ethics boards, licensing boards, and funding agencies, should also be involved.21

Although challenging to define, it is even more difficult to identify duplicate publication.19 Thus, the responsibility to recognize and report duplication rests with all who come in contact with the study, including colleagues aware of one's work, peer reviewers, editors, and the readership of the journal. At times, clandestine duplicate publications are divulged when someone reads a journal article and informs the editor of the journal or an official of the authors' institution.

Actions and Sanctions Once Covert Duplication Is Identified 

Once inappropriate duplicate publication has been recognized, investigated, and confirmed, there are many suggested actions. These actions are intended to correct the record, notify others that misconduct has taken place, and provide incentive to authors not to replicate this unethical behavior.

Some or all of the following have been recommended and should be based on the circumstances of the situation. If duplication is identified before or after acceptance but before publication, the manuscript should be rejected outright.7, 9 If duplicate publication is identified after publication, the editor should communicate in one or more of the following ways: (1) send a letter of reprimand to the authors5, 20; (2) notify editors of other journals19, 20; (3) inform the authors' clinical institution5, 11, 19, 20, 21, 22; (4) inform the authors' academic institution5, 11, 19, 20, 21, 22; (5) inform ethics/institutional review boards21, 22; (6) inform professional organizations18; (7) inform funding/granting agencies (eg, National Institutes of Health)5, 19, 20; (8) inform indexing services (eg, PubMed)19, 20, 21; and (9) inform a professional ethics body (eg, Office of Research Integrity).22

Once the appropriate bodies have been informed, the next step is to make a correction to the record, which may be accomplished in several ways. A notice of duplicate/redundant publication or plagiarism may be published in the journal.5, 10, 19, 20, 21, 22 A notice of retraction may also be published.5, 7, 22 Some writers suggested that the journal publish a letter of apology from the authors.18 Others recommended that the journal publish reprimanding editorials.11 Finally, articles may be retracted from journals5, 7, 9, 22 and/or from indexing services.5, 7, 11, 22

There are recommended sanctions for authors who have submitted covert duplicate or redundant publications. Several writers suggested restricting authors from future submissions to journals in which the misconduct was recognized.10, 11, 19, 20 A more punitive sanction recommended is to restrict authors from future publication in journals belonging to an editorial group, thereby greatly reducing the number of journals to which a sanctioned author may submit a manuscript.11

How to Prevent Duplication 

Prevention is possibly the best approach to duplicate publication. Both the editor and the author can take steps toward preventing this from becoming an issue. First, the author should read in detail the instructions for authors of the journal to which the manuscript is being submitted. This document will usually provide detailed information regarding the journal's policy toward redundant publication. If uncertain, the author should contact the editor and ask for any necessary clarification. The author should fully disclose to the editor in the cover letter and in the manuscript that some or all of the same study contents or data have been used/will be used in published articles, currently submitted articles, unpublished papers, or any other article relating to the data or content of the article.5, 7, 12, 18 The author should include in the cover letter or sign a statement denying or disclosing overlap with any other work.7, 19, 20 It is suggested that copies of the other work be submitted to the journal at the same time as the study for consideration.7, 21 As a rule of thumb, Tobin10 stated, “[n]o matter how small the overlap, authors need to inform us [editors] about related work.”

Authors should be cautious to report information about their study to the media, funding agencies, government agencies, or others who disseminate information before the publication of their study.7 Some reporting in advance of publication may be warranted but should be discussed with the editor and agreed upon in advance.

Peer reviewers should notify the editor if duplicate publication is supposed during the review process.1, 19, 20 After publication, readers are encouraged to notify the editor if there is suspicion of duplicate publication.

Editors should ensure that their journal's policy on duplicate publication is clearly stated and easy to follow.1, 5, 11, 19, 20, 21 Editors should publish editorials or commentaries to educate readers about this topic.1 Journals should have in place definitions, procedures for handling suspected manuscripts, reporting policies, corrections/retractions, and sanctions.16, 22 Editors may screen each manuscript for redundancy if there are enough resources in their journal office to complete this task successfully. An alternate approach may be to randomly screen submissions for signs of duplication.1, 11, 19, 20 However, screening will not account for manuscripts that are currently in press, have been indexed in an obscure database, or have simultaneously been submitted to another journal. Some encourage editors to use deterrents, such as reporting suspected manuscripts, publishing reprimanding articles, and contacting the offending authors' institutions.11, 22 However, I feel strongly that prevention is the best approach, hence the publication of this editorial.

The JMPT Policy and Conclusion 

It is my hope that through this editorial, the readership of the JMPT will have a better understanding of this complex issue. The JMPT's policy regarding repetitive, duplicate, or redundant publications is presented below. Additional information is included in the JMPT instructions for authors, available on the journal's website at www.mosby.com/jmpt.

The JMPT does not publish articles containing material that has been reported at length elsewhere. The corresponding author must include in the cover letter a statement to the editor about all submissions and previous materials that might be considered to be redundant or duplicate publication of similar work, including if the manuscript includes materials on which the authors have published a previous report or have submitted a related report to another publication. Copies of the related material may be requested by the editor in order to assist with the editorial decision of the paper.

If redundant or duplicate publication is attempted or occurs without proper disclosure to the editor, editorial action will be taken as follows. If it is confirmed that a paper is a duplicate or redundant publication and is discovered in the prepublication phase, the paper will be rejected, even if an accept notice has been distributed previously to the authors. If duplicate or redundant publication is confirmed after publication, the paper will be retracted and the appropriate boards/institutions notified.