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Special Reports |
1 From the Department of Radiology, St Vincent’s Hospital (S.S.H., J.H.B., S.L.J., Y.H.P.), Department of Radiology, Kangnam St Mary’s Hospital (S.H.P., K.H.C.), and Department of Biostatistics (H.H.S.), Catholic University of Korea, 505 Banpo-dong, Seocho-ku, Seoul 137-701, Korea. Received July 23, 2001; revision requested September 24; final revision received April 15, 2002; accepted May 17. Address correspondence to H.H.S. (e-mail: hhsong@catholic.ac.kr).
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ABSTRACT |
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 TOP ABSTRACT INTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSION REFERENCES |
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MATERIALS AND METHODS: The author contribution lists of Radiology articles published between 1998 and 2000 with at least three authors were reviewed. The fulfillment of ICMJE criteria for authorship and the contribution percentage were assessed according to each researcher’s position in the byline and nationality (American vs international), number of researchers per article, and year of publication.
RESULTS: Sixty-eight percent of researchers fulfilled the ICMJE authorship criteria. Position in the byline indicated a significant difference in fulfillment (P < .001): 98.9% and 85.3% for the first and second authors, respectively, and 52.8% and 66.5% for the middle and last authors, respectively. American researchers had a higher percentage (78%) of fulfillment than did international researchers (57%) (P < .001). Fulfillment decreased as the number of authors per article increased (P < .001), although there was no significant change throughout 1998–2000. The mean contribution percentages decreased greatly from first to second to last to middle authors. American researchers had a significantly larger mean contribution percentage than did international researchers. Of the total 6,686 researchers, 2,316 (35%) contributed to one or two categories. This rate was higher for middle and international authors.
CONCLUSION: The 68% fulfillment of criteria for authorship was closely related to the large number of researchers contributing to one category or to categories belonging to the same ICMJE criterion.
© RSNA, 2002
Index terms: Education • Radiology and radiologists, research
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INTRODUCTION |
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TOPABSTRACTINTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSION REFERENCES |
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In 1985, the International Committee of Medical Journal Editors (ICMJE) established the criteria for authorship, which were modified during the May 2000 ICMJE meeting. In the criteria for authorship, the ICMJE states the following (7):
All persons designated as authors should qualify for authorship, and all those who qualify should be listed. Each author should have participated sufficiently in the work to take public responsibility for appropriate portions of the content. One or more authors should take responsibility for the integrity of the work as a whole, from inception to published article. Authorship credit should be based only on 1) substantial contributions to conception and design, or acquisition of data, or analysis and interpretation of data; 2) drafting the article or revising it critically for important intellectual content; and 3) final approval of the version to be published. Conditions 1, 2, and 3 must all be met. Acquisition of funding, the collection of data, or general supervision of the research group, by themselves, do not justify authorship.
The order of authors in the byline provides little information regarding each author’s contribution in research articles with multiple authors. To disclose a researcher’s specific contributions for journal readers, the use of a contribution list was proposed (1,8) and adopted by The Lancet in 1997. In this disclosure, the authors were not required to use any predefined categories or checklists of contributions but were free to devise their own descriptions of the tasks each author performed. Subsequently, a few journals began to publish author contributions, and Radiology is the only imaging journal that does. Radiology has published author contributions in the form of a list of specific categories since 1998. This information is published on the first page of each original research article (9). Unlike in the contribution list of The Lancet, each author of an article published in Radiology must select from among 14 categories those that best fit the tasks that he or she performed. Radiology also requests that guarantors be identified—that is, those who have responsibility for the integrity of the work as a whole (10).
Yank and Rennie (11) performed a preliminary analysis of the author contribution lists in The Lancet during a 6-month period from July to December 1997 and suggested that their results needed to be replicated in larger studies of other journals. In this spirit, we initiated our study—we analyzed author contribution lists from articles published during a 3-year period in Radiology. The purpose of this study was to determine the number of researchers who fulfill the ICMJE authorship criteria and to evaluate the extent and nature of individual contributions.
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MATERIALS AND METHODS |
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TOPABSTRACTINTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSION REFERENCES |
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To determine authorship trends among researchers listed in the bylines, researchers were grouped as first, second, middle, and last authors. The last researcher in the byline was defined only as the "last author." Middle authors were those not listed as first, second, or last. Thus, for articles with three authors, there was no middle author. Also, to assess geographic differences in authorship trends, research articles were defined as having either American or international authorship according to researcher nationality, as determined by the institution(s) documented in the article. In articles published in collaboration with both American and international authors, the nationality was that of the first author.
How Many Researchers Fulfill ICMJE Criteria for Authorship?
There are 14 categories in the author contribution list for Radiology. To study the association between this contribution list and the three conditions of the ICMJE authorship criteria, we identified categories in Radiology that applied to each condition. We consider that contribution to any of the following eight categories would fulfill the first condition of the ICMJE criteria for authorship—that is, any aspect of conception and design, acquisition of data, or analysis and interpretation of data: "study concepts," "study design," "literature research," "clinical studies," "experimental studies," "data acquisition," "data analysis/interpretation," and "statistical analysis." The second condition of the ICMJE criteria—that is, any part of drafting the article or revising it critically for important intellectual content, includes four categories: "manuscript definition of intellectual content," "manuscript preparation," "manuscript editing," and "manuscript revision/review." The third condition of the ICMJE criteria, which consists of final approval of the version to be published, includes a single category: "manuscript final version approval."
In a one-to-one comparison of the Radiology contribution list categories and ICMJE conditions, the category of "manuscript final version approval" in Radiology poses a problem, since this category was first included in the contribution list in December 2000. Thus, we presumed that all authors of Radiology whose manuscript was published from 1998 to 2000 justly approved their final version, implying that all authors fulfilled the third condition for authorship criteria. This is not unreasonable, because the copyright transfer form signed by all authors stipulates it.
In addition, the category of "guarantor of integrity of entire study" was omitted from our comparison, since it was not included in the ICMJE conditions. In summary, by excluding "guarantor of integrity of entire study" and "manuscript final version approval," we considered 12 categories in our study of fulfillment of ICMJE’s authorship criteria. We ascertained the percentage of researchers who fulfilled the first two conditions of the ICMJE criteria, and these percentages were compared with the researchers’ positions in the byline, researchers’ nationality, number of researchers per article, and the year of publication.
Assessment of Extent and Nature of Contributions
In the assessment of the percentages or types of each researcher’s specific contributions, there is no need to exclude the category of "guarantor of integrity of entire study," unlike in the study of the fulfillment for authorship criteria. We wanted to find out which author had a role as "guarantor of integrity of entire study." Also, since we examined data from 1998 to 2000 in Radiology, we excluded the category of "manuscript final version approval" for the reason explained above.
In summary, for the study of the extent and nature of researcher contributions, we considered 13 categories by excluding "manuscript final version approval." To assess the extent of the contributions of each researcher to an article with respect to the 13 categories, we developed a "contribution percentage." The actual contribution of an author is difficult or even impossible to quantify. However, the contribution categories checked for each author in an article provide some indication of workload, and thus, a measure of "contribution percentage" can be computed. The relative individual contribution of an author is computed on the basis of the number of categories in which the author participated, when the total number of categories checked in that article is counted as a 100% contribution. On the basis of the assumption that each category in an article implies equal contribution, the contribution percentage of an author was calculated as 100m/n, where m is the number of categories checked by that author and n is the number of categories checked by all authors in that article. For example, a contribution percentage of 90% for a researcher means that when the total number of categories checked by all researchers in that article is 10, the researcher participated in nine categories.
We compared the mean contribution percentage of all researchers according to position in the byline and nationality. In addition, we evaluated the percentages and types of contributions of researchers who contributed to one or two categories and compared them according to each researcher’s position in the byline or nationality.
Statistical Analysis
Data were analyzed by using the 
2 test or analysis of variance with Scheffé multiple comparison methods (12). Statistical significance depended on the total number of samples, and for a large sample, even a slight difference of percentages or means can be highly significant. In our study, sample size was determined on the basis of the number of articles or the number of researchers. Therefore, the contribution percentage or mean difference in the number of researchers, which was 6,686 in our study, was calculated more conservatively with a significance level of .01. However, for a statistical evaluation of the number of articles, the usual significance level of .05 was applied.
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RESULTS |
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TOPABSTRACTINTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSION REFERENCES |
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There was variation in the number of contribution categories per article, with a mean of 11.4 categories ± 1.2. Nine hundred seventy-seven (92%) of the 1,068 articles assessed had between 11 and 13 categories when the category of "manuscript final version approval" was not included. Despite these variations, however, fulfillment of authorship criteria results and researcher contribution percentages did not correlate with the numbers of documented contribution categories (Table 1) (P > .01 for both).
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The geographic difference of the percentages of researchers who fulfilled all three conditions for authorship criteria was significant, with a larger percentage (78%) of American researchers compared with that (57%) of international researchers (P < .001). This difference was mainly due to the second criterion, with a higher percentage (84%) of fulfillment for the American researchers compared with that (68%) of the international researchers. The relationship between the percentages of fulfillment of ICMJE criteria and the number of researchers per article was negatively associated, with the percentages of fulfillment decreasing as the number of authors per article increased (P < .001).
The percentages of authors who fulfilled all three conditions for authorship did not change throughout 1998–2000 (66.3% in 1998, 68.9% in 1999, and 67.4% in 2000) (P = .18); this was true even when the first or second criterion was examined separately.
Extent and Nature of Contributions
Thirteen of the 14 contribution categories (excluding "manuscript final version approval") were analyzed, and the extent of contribution was evaluated by using the contribution percentage of each researcher as noted above. The mean percentages shown in Table 3 are classified according to the number of researchers per article, researcher position in the byline, and researcher nationality. Mean percentages decreased from 61% for articles with three researchers to 31% for articles with more than 10 researchers, with an overall mean contribution of 40% ± 28. These mean percentages varied greatly depending on researcher position in the byline, which decreased from 82% to 51% to 35% to 25% for the first, second, last, and middle authors, respectively. For each researcher position in the byline, a pattern of decreasing mean percentages persisted as the number of researchers per article increased. Overall, the mean contribution percentage of American researchers (45%) was significantly higher than that of international researchers (35%) (P < .001).
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Researchers Contributing to One or Two Categories
In Table 5, 1,133 (17%) of 6,686 researchers contributed to a single category, and 1,183 (18%) researchers contributed to two categories. The percentages of researchers with contributions to one or two categories were significantly higher for middle and international authors (P < .001 for both). The authors contributing to one category most commonly participated in "clinical studies" (348 of 1,133, 30.7%), "data acquisition" (212 of 1,133, 18.7%), and "manuscript revision/review" (170 of 1,133, 15.0%), with participation in the rest of the categories at 1.3% to 6.4%. Twenty-six authors (1.4%) contributed to the single category of "guarantor of integrity of entire study," and 25 of the 26 were international authors.
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DISCUSSION |
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TOPABSTRACTINTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSION REFERENCES |
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Other reasons that motivated authors to add as many co-authors as possible have been suggested: for example, honorary or guest authorship due to the need to please someone such as the head of the group or the person who acquired funding for the study by including him or her, even if that person did not substantially contribute to the research. Another example is swap authorship, defined as the listing of another person’s name in one’s article and vice versa (1,4,5).
Since the ICMJE authorship criteria were established in 1985 and implementation has been encouraged in many medical journals, numerous investigators have studied the extent to which these authorship criteria have been fulfilled among published articles. Goodman (14) found that about one third of 84 authors did not meet authorship criteria in an analysis of 12 articles. After surveying 184 research articles with multiple authors from 10 medical journals, Shapiro et al (15) reported that 268 (26%) of 1,014 authors had insufficient contributions to the research to merit authorship. Hoen et al (16) studied 1 year of issues of the Dutch Journal of Medicine and found that 128 (36%) of 352 authors failed to fulfill ICMJE authorship criteria. Yank and Rennie (11) found that 346 (44%) of 785 authors in 6 months of issues of The Lancet did not fulfill ICMJE authorship criteria. In our analysis of research articles published in Radiology between 1998 and 2000, 2,172 (32.5%) of 6,686 researchers in the bylines did not meet ICMJE criteria. According to the policies of both Radiology and the ICMJE, researchers who do not have substantial contribution to all three conditions for authorship criteria should only be listed in the acknowledgments (7,10). However, there were researchers who did not meet the authorship criteria who appeared in the bylines.
Similar to the findings of the previous study of Yank and Rennie (11), our findings showed that researcher participation in the first condition of authorship criteria—that is, contributions to conception and design, acquisition of data, and analysis and interpretation of data—was higher than that in the second condition—that is, contributions to drafting the article or revising it critically for important intellectual content.
The "substantial" contribution stated in the ICMJE criteria supports exclusion of researchers with a limited role in all three conditions, but simply checking each of the three ICMJE conditions does not reveal the type or degree of each author’s contribution. On the other hand, if the 13 Radiology contribution categories are used in a meaningful and reproducible way, these categories can reveal more detailed information than can the three ICMJE conditions.
The results of our analysis of these two methods of disclosure of author contributions demonstrated a misunderstanding or unawareness of the authorship criteria, or, if the criteria were well understood, the presence of honorary or guest authors in Radiology. A few indications of a limited role of such authors are as follows: 1,133 authors checked a single category, a clear indication of not fulfilling the authorship criteria—that is, 348 authors checked only "clinical studies," 212 checked only "data acquisition," and 170 checked only "manuscript revision/review." Such results were more common among middle and international authors.
Although the researcher(s) listed as "guarantor of integrity of entire study" should make a substantial contribution to all three parts of the authorship criteria, in our opinion, as well as be responsible for the integrity of the entire study, there were 26 authors who contributed solely to the category of "guarantor of integrity of entire study," and 25 of them were international authors. For those authors who checked two categories, the results were similar to those of authors who checked a single category. Under our presumption of the third condition of authorship criteria being fulfilled, each author has to participate in more than two categories to meet both the first and second conditions of the ICMJE. Authors contributing to one category do not meet both criteria. Also, authors contributing to two categories may not fulfill both criteria, unless each category comes from the first and second conditions of the ICMJE. All of the authors contributing to one category (1,133 authors) and 656 (56%) of 1,183 authors contributing to two categories did not meet the authorship criteria.
Including 26 authors with single contributions to the category of "guarantor of integrity of entire study," the authors who contributed to one or two categories represented 82% (1,789 of 2,172) of authors who did not fulfill the ICMJE criteria. Consistent with the results of Shapiro et al (15), these authors were principally responsible for a decreased fulfillment of authorship. These results show that there is an evident need for clarification and continual education of the terms of the establishment of the authorship criteria, especially for non-American researchers. Although there may not be wide agreement on or recognition of ICMJE authorship criteria, we believe that fulfilling the ICMJE criteria as the standard for authorship is essential for justified authorship.
In our analysis, we examined the association between the percentage of researchers who fulfilled the authorship criteria and the number of researchers per article, as well as the researchers’ positions in the byline. These percentages decreased significantly as the number of researchers per article increased, from 89% in an article with three authors to 61% in an article with more than 10 authors.
The mean contribution percentages showed the same trend, which demonstrates that the principal problem for authorship seems to be closely related to the number of researchers per article. This increased number of researchers per article also shows a decreased individual contribution to the research. In our study, there were several differences in authorship trends between American and international researchers. Articles with international researchers had a lower fulfillment of ICMJE authorship criteria, a higher mean number of researchers per article, a lower contribution percentage per researcher, and a higher number of researchers contributing to a single category. It is possible that factors such as sociocultural differences, different reward, and tenure systems might determine the geographic differences of authorship trends.
Although Radiology has made an effort to reduce inappropriate authorship, the results of our study showed no substantial improvement of the fulfillment of authorship criteria from 1998 to 2000, thus demonstrating that researcher awareness or interest in authorship criteria has not increased during this 3-year period.
Individual Author Contributions
Overall, the percentages of researcher contributions varied in each category. The categories most frequently participated in, including "manuscript revision/review," "clinical studies," and "data acquisition," had a 50%–60% contribution rate. According to researcher position in the byline, as in previous studies (15,17), the contribution of the first author was noteworthy, with percentages exceeding 60% contribution in all categories. Contributions of nonfirst authors varied greatly, however, with a relatively larger contribution of the second authors compared with that of the last or middle authors, and there were markedly variable types and numbers of categories frequently participated in. With regard to the geographic differences among researcher contributions, there was a tendency toward lower participation in articles by international researchers than that in articles by American researchers in all the contribution categories. This tendency toward lower participation was correlated closely with a greater number of researchers per article, a lower contribution percentage per researcher, and a larger proportion of researchers contributing to a single category.
To quantify individual author contributions, in an era of no available information about each author’s contributions, such as self-documented or checked categories of author contributions, Moulopoulos et al (18) considered a simple contribution percentage based on the total number of authors, computed by assuming that the contributions of different authors in an article were all equal. To compare the curricula vitae of four candidates for a professional appointment, they further devised a different measure of contribution by giving more weight to the first or higher-positioned authors in the byline. However, when the contribution of the last authors is greater than that of the middle authors, as was shown in our analysis, this mea-sure is not valid. In our study, author contributions could be quantified and compared simply by calculating the contribution percentage. Although contribution percentage as an index for authorship is simple and easy to apply, it may be difficult to generalize because it requires some premises, such as the presence of specific categorization of author contributions and a presumption of giving equal value to all contribution categories.
The order of authorship in the byline is a joint decision of the authors, who should be prepared to explain the order in which they are listed (7). If the meaning of the author order can be explained, the author order in the byline may be a way to reduce inappropriate authorship, in addition to listing each author’s specific contribution. However, findings in previous studies of researcher contributions, along with our study results, demonstrated the variable extent and nature of researcher contributions, despite their positions in the byline (1,11,15,17).
There have been some preconceptions about author order in the byline. In a typical example, many authors reserve the position of last author for an honorary person, such as a senior staff member or department director, but this may encourage honorary authorship (3). If a brief sentence is attached at the beginning or end of an article or within the author contribution list regarding how author order in the byline was determined, we believe it will provide useful information to journal readers. For instance, the sentence "Except for the first author, author order in the byline was arranged alphabetically by last name" indicates that author order in the byline was not meaningful. To the contrary, the sentence "The order of author names was based on the number of contributions made by each" indicates that the author order in the byline was meaningful.
In summary, our analysis of the information in the author contribution list demonstrated some important findings. First, in our study, only 68% of the researchers listed in the byline fulfilled the ICMJE authorship criteria, and this low percentage of fulfillment was closely related to the number of researchers per article, especially to the number of researchers who contributed to a single category. Second, the order of researcher names in the byline had limited reference to the extent and nature of contributions made to the research. Third, geographic differences exist in the nature and extent of researcher contributions and in the fulfillment of authorship. The fulfillment of authorship of American researchers seems to be greater than that of authors from other countries and is partly related to the smaller number of researchers contributing to a single category in American articles. As suggested by Athanasoulis (5) and Probyn et al (19), our results are one piece of evidence suggesting the necessity for continual education on valid authorship by various means, especially for international researchers. In addition, efforts to make the ICMJE criteria more widely known may reduce confusion regarding authorship for those researchers who are unfamiliar with the ICMJE criteria (16). Our findings should be interpreted with the understanding that our results were derived only from the journal Radiology, and thus, one should be cautious not to generalize them to other journals.
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ACKNOWLEDGMENTS |
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FOOTNOTES |
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Abbreviation: ICMJE = International Committee of Medical Journal Editors
Author contributions: Guarantors of integrity of entire study, H.H.S., S.H.P.; study concepts, S.S.H., S.H.P., K.H.C.; study design, S.S.H., H.H.S., Y.H.P.; literature research, S.S.H.; data acquisition, S.S.H., J.H.B., S.L.J.; data analysis/interpretation, S.S.H., J.H.B., S.H.P.; statistical analysis, H.H.S., J.H.B.; manuscript preparation, S.S.H., H.H.S.; manuscript definition of intellectual content, H.H.S., S.H.P.; manuscript editing, H.H.S., S.S.H.; manuscript revision/review and final version approval, all authors.
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REFERENCES |
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TOPABSTRACTINTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSION REFERENCES |
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