LIVER TRANSPLANTATION 20:355–360, 2014
SPECIAL ARTICLE
Fate of Abstracts Presented at the 2004-2008 International Liver Transplantation Society Meetings Patrick J. Hackett,1 Marina Guirguis,2 Nozomi Sakai,3 and Tetsuro Sakai1,4 Department of Anesthesiology, University of Pittsburgh Medical Center, Pittsburgh, PA; 2West Virginia University, Morgantown, WV; 3University of California Berkeley, Berkeley, CA; and 4McGowan Institute for Regenerative Medicine, University of Pittsburgh School of Medicine, Pittsburgh, PA
1
Only 20.5% to 61.6% of abstracts presented at biomedical meetings are subsequently published as full-length articles. The aim of this study was to analyze the abstract-to-publication rate of International Liver Transplantation Society (ILTS) meeting abstracts. Abstracts presented at 5 consecutive annual ILTS meetings (2004-2008) were included to ensure a minimum follow-up period of 4 years. For each abstract, a PubMed Central search was conducted with the first author’s name and affiliation along with keywords from the title. The following abstract characteristics were examined and used to obtain the abstractto-publication rate: (1) the year of presentation, (2) the presentation category (plenary session, concurrent oral presentation, or poster presentation), (3) the type of study (randomized clinical study, case report, other clinical study, or basic science study), (4) the first author’s discipline (surgery, medicine, anesthesiology/critical care medicine, pathology, radiology, or pharmacology), and (5) the location of the authors (ie, an English-speaking or non–English-speaking country). A total of 2345 abstracts (469 6 144 abstracts per meeting) were presented, and 913 of those abstracts (38.9%) were expanded into fulllength publications. It took 46 months for 90% of the abstracts to be published as full-length journal articles. The abstract-topublication rates differed with the year of abstract presentation (50.2% in 2004, 45.9% in 2005, 47.6% in 2006, 30.6% in 2007, and 30.3% in 2008; P < 0.001), with the presentation category (49.6% for plenary sessions, 48.5% for concurrent oral presentations, and 34.8% for poster presentations; P < 0.001), and with the type of study (66.7% for randomized clinical studies, 63.1% for basic science studies, 36.7% for other clinical studies, and 35.0% for case reports; P < 0.001). Abstracts from authors from non–English-speaking countries had a higher publication rate (41.1% versus 33.6%, P < 0.001). No differences C 2014 AASLD. were found between first authors’ disciplines. Liver Transpl 20:355-360, 2014. V Received November 5, 2013; accepted November 24, 2013. Presenting abstracts at national meetings allows researchers to share their scientific discoveries with a large audience, and this should lead them to submit their findings as full-length manuscripts to peer-
reviewed journals for publication. Unfortunately, not all researchers follow through with this process after the presentation of their abstracts. This failure to publish abstract data in full-length articles limits the
Abbreviations: CCM, critical care medicine; ILTS, International Liver Transplantation Society. Financial support for this work was provided solely by the institutions and departments named in the affiliations. There are no conflicts of interest to report. Tetsuro Sakai designed the study. Patrick J. Hackett, Marina Guirguis, and Nozomi Sakai collected the data. Tetsuro Sakai verified the data. Patrick J. Hackett and Tetsuro Sakai analyzed the data. Patrick J. Hackett and Tetsuro Sakai wrote the paper. Marina Guirguis and Nozomi Sakai reviewed the manuscript. This article was presented in part as a poster presentation at the 19th Annual International Congress of the International Liver Transplantation Society (Sydney, Australia, June 12-15, 2013) and at the 67th Annual PostGraduate Assembly in Anesthesiology (New York, NY, December 13-17, 2013). Address reprint requests to Tetsuro Sakai, M.D., Ph.D., Department of Anesthesiology, University of Pittsburgh Medical Center, UPMC Montefiore, N469.11, 200 Lothrop Street, Pittsburgh, PA, 15213. Telephone: 412-648-6077; FAX: 412-648-6014; E-mail: [email protected] DOI 10.1002/lt.23807 View this article online at wileyonlinelibrary.com. LIVER TRANSPLANTATION.DOI 10.1002/lt. Published on behalf of the American Association for the Study of Liver Diseases
C 2014 American Association for the Study of Liver Diseases. V
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dissemination of knowledge, the opportunity for more rigorous peer review of the findings, and ultimately could indicate the need to improve society meetings and their related specialties. The abstract to peerreviewed publication rate has been reported to be 20.5% to 61.6% for various medical specialties.1-20 In the field of liver transplantation, the annual meeting of the International Liver Transplantation Society (ILTS) has attracted a large number of multidisciplinary physicians and researchers with shared scientific interests. No prior study has investigated the abstract-to-publication rate of work presented at this meeting. The aim of this study was to analyze the fate of abstracts presented at ILTS meetings and determine any particular qualities of abstracts that were later expanded and published as full-length journal articles.
MATERIALS AND METHODS No institutional review board approval was sought for this study because all data were publicly available.
Study Materials Abstracts presented at 5 consecutive annual ILTS meetings (2004-2008) were identified in supplements to Liver Transplantation. The most recent meeting included in the study was the 2008 meeting to guarantee a minimum 4-year follow-up period and thus allow adequate time for the publication of full-length articles.1-3
Abstract Data Each abstract was categorized as follows: the year of presentation, the presentation category (plenary session, concurrent oral presentation, or poster presentation), the author’s subspecialty [surgery, medicine (hepatology, immunology, or infectious disease), anesthesiology/critical care medicine (CCM), pathology, radiology, or pharmacology], the type of study (prospective randomized study, retrospective clinical study, case report, or basic science study), and the location of the authors (ie, an English-speaking or non–English-speaking country). If an abstract listed multiple subspecialties and/or multiple affiliations in multiple countries, only the first author’s subspecialty and affiliation/country data were considered. When the subspecialty was not clearly identified (eg, liver unit), the first author’s name, the last author’s name, or both were entered into the Google search engine (last accessed on December 31, 2012) to identify the subspecialty. The countries of the authors’ affiliated institutions were later categorized as either countries with English as the dominant or official language (eg, United States, United Kingdom, Canada, Australia, New Zealand, Republic of Ireland, South Africa, India, Pakistan, Philippines, and Singapore) or non–Englishspeaking countries.
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Full-Length Manuscript Publication Search Strategy PubMed (last accessed on December 31, 2012) was used exclusively to search for publications on the basis of abstracts. The advanced search setting, PubMed Advanced Search Builder (last accessed on December 31, 2012), was used for each abstract. In the builder, the first author’s name (eg, sakai t) was entered as the author, and after the selection of the “and” linkage, the first author’s affiliation (eg, Pittsburgh) was entered as the affiliation. To narrow the search results, a specific time range including the year before the abstract presentation and the date of the search (eg, if the abstract was presented at the ILTS meeting in 2005, the range was 2004-2012) and some of the keywords in the abstract title (eg, liver or liver transplantation) were further entered. Each potential candidate manuscript was reviewed (the list of authors, the title, the abstract, and the disclosure of prior presentation of the work in the manuscript if available). When it was unclear whether an article was indeed based on the abstract of interest, the senior author of the present work (T.S.) made the final decision. Once a peer-reviewed article of interest was identified, the year of publication and the peer-reviewed journal’s name were recorded. The 5-year impact factor of each journal was identified with Journal Citation Reports (ISI Web of Knowledge, Thomson Reuters, New York, NY).21
Data Analyses The data are reported as means and standard deviations, medians and ranges, or numbers and percentages as appropriate. To compare abstract-topublication rates by the year of presentation, type of study, author’s subspecialty, presentation category, or language, Pearson’s chi-square test or Fisher’s exact test, as indicated, was used. A log-rank (MantelCox) test was used to compare the time from abstract presentation to manuscript publication between presentation years. A P value less than 0.05 was considered statistically significant. The statistical analysis was performed with GraphPad Prism 6 (GraphPad Software, Inc., La Jolla, CA).
RESULTS ILTS Meeting Abstracts The venues and dates of the ILTS meetings included in this study were as follows: the 10th ILTS meeting was held in Kyoto, Japan (June 9-12, 2004); the 11th ILTS meeting was held in Los Angeles, CA (July 2023, 2005); the 2006 Joint International Congress of the ILTS, the European Liver and Intestinal Transplant Association, and the Liver Intensive Care Group of Europe was held in Milan, Italy (May 3-6, 2006); the 13th ILTS meeting was held in Rio de Janeiro, Brazil (June 20-23, 2007); and the 2008 Joint
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International Congress of the ILTS, the European Liver and Intestinal Transplant Association, and the Liver Intensive Care Group of Europe was held in Paris, France (July 9-12, 2008). A total of 2345 abstracts were presented; there were 469 6 144 abstracts per meeting (299 abstracts in 2004, 338 in 2005, 515 in 2006, 561 in 2007, and 634 in 2008). The majority of the abstracts were presented as posters (68.5% 6 8.4% as poster presentations, 26.4% 6 7.8% as concurrent oral presentations, and 5.1% 6 0.9% at plenary sessions), and most of the abstracts were based on retrospective clinical studies (81.2% 6 4.4% for retrospective clinical studies, 9.4% 6 2.4% for case reports, 7.0% 6 1.1% for basic science studies, and 2.5% 6 2.0% for prospective randomized studies). Surgery was the main subspecialty of the first authors (74.5% 6 4.0% in surgery, 12.8% 6 2.2% in medicine, 8.2% 6 1.8% in anesthesiology/CCM, 2.0% 6 1.9% in pathology, 1.5% 6 0.7% in radiology, 0.6% 6 0.3% in pharmacology, and 0.2% 6 0.6% in other subspecialties). Authors from English-speaking countries were responsible for 30.1% 6 7.2% of the abstracts, and authors from non– English-speaking countries were responsible for 69.9% 6 7.2%. The nations of the affiliated institutions of the first authors were as follows: the United States (n 5 532 or 26.7%), Italy (n 5 272 or 11.6%), Brazil (n 5 226 or 9.6%), South Korea (n 5 177 or 7.5%), Japan (n 5 176 or 7.5%), Spain (n 5 115 or 4.9%), France (n 5 110 or 4.7%), Germany (n 5 109 or 4.6%), United Kingdom (n 5 80 or 3.4%), Taiwan (n 5 72 or 3.1%), China (n 5 55 or 2.3%), Netherlands (n 5 54 or 2.3%), Turkey (n 5 50 or 2.1%), Poland (n 5 42 or 1.8%), Canada (n 5 37 or 1.6%), Saudi Arabia (n 5 25 or 1.1%), Argentina (n 5 24 or 1.0%), Australia (n 5 22 or 0.9%), Austria (n 5 21 or 0.9%), Egypt (n 5 19 or 0.8%), Belgium (n 5 18 or 0.8%), India (n 5 13 or 0.6%), Finland (n 5 11 or 0.5%), Switzerland (n 5 11 or 0.5%), Sweden (n 5 11 or 0.5%), and 20 other countries (a total of 63 abstracts with fewer than 10 abstracts from each country).
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Figure 1. Abstract-to-publication rate. This stacked column graph shows the total number of abstracts presented at the 2004-2008 ILTS meetings, and each column is divided into abstracts with published full-length manuscripts and abstracts without published full-length manuscripts. The publication rates are shown beneath the years; the combined publication rate was 38.9%. A statistically significant decline (P < 0.001) in the rate from 2004 to 2008 was noted.
(150/299 abstracts) for the 2004 ILTS meeting, 45.9% (155/338) for the 2005 ILTS meeting, 47.6% (245/515) for the 2006 ILTS meeting, 30.7% (172/ 561) for the 2007 ILTS meeting, and 30.3% (192/ 634) for the 2008 ILTS meeting. The rates were also higher for abstracts presented at plenary sessions and concurrent oral sessions (49.6% for plenary session abstracts, 48.5% for concurrent oral session abstracts, and 34.8% for poster session abstracts; P < 0.001) and for randomized clinical studies and basic science studies (66.7% for randomized clinical studies, 63.1% for basic science studies, 36.7% for retrospective clinical studies, and 35.0% for case reports; P < 0.001). Abstracts from authors from non– English-speaking countries had a higher publication rate (41.1% versus 33.6%, odds ratio 5 1.4, 95% confidence interval 5 1.15-1.66, P < 0.001). No differences were found between the disciplines of first authors (Fig. 3).
Abstract-to-Publication Rate Nine hundred thirteen of the 2345 abstracts (38.9%) were ultimately published as full-length, peerreviewed journal articles (Fig. 1). A list of top 20 journals is provided in Table 1. The top 6 journals in which the ILTS abstracts were published as fulllength articles were Liver Transplantation (264 abstracts), Transplant Proceedings (139), Transplantation (86), American Journal of Transplantation (70), Transplant International (61), and Clinical Transplantation (42). Ninety percent of the abstracts were published as full-length articles within 46 months after abstract presentation. No statistical difference was found between the presentation years for the time from abstract presentation to full-length manuscript publication (P 5 0.73; Fig. 2). The abstract-to-publication rates varied significantly (P < 0.001) with the year of presentation: 50.2%
DISCUSSION There were 2345 abstracts presented at 5 consecutive annual ILTS meetings (2004-2008), and 38.9% were published as full-length articles within the minimum 4-year follow-up period; this rate is comparable to other reported rates.1-20 Several abstract characteristics were found to be associated with a higher publication rate, including oral presentations, randomized controlled clinical trials, and basic science studies, and this has been supported by similar studies.2,4,5 The importance of publishing full-length manuscripts expanded from meeting abstracts cannot be overemphasized. The full-length manuscript publication rate of meeting abstracts not only illustrates the quality of research conducted by an institution’s investigators but also portrays the activity and reputation of a particular scientific meeting and its society
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TABLE 1. Top 20 Journals That Published Full-Length Manuscripts of Abstracts Presented at ILTS Meetings (20042008) Journal Name Liver Transplantation Transplant Proceedings Transplantation American Journal of Transplantation Transplant International Clinical Transplantation Hepatogastroenterology Pediatric Transplant Surgery Journal of Surgical Research Digestive Disease and Sciences Anesthesia and Analgesia Annals of Transplantation Journal of Hepatology Annals of Surgery American Surgeon Critical Care Medicine Gastroenterology Journal of the American College of Surgeons World Journal of Surgery
Publications (n)
5-Year Impact Factor*
264 139 86 70 61 42 19 18 13 13 12 11 10 10 8 6 6 6 6 6
3.944 0.952 3.781 6.192 3.155 1.884 0.774 1.500 3.373 2.018 2.260 3.300 0.815 9.858 6.329 0.918 6.124 12.821 4.500 2.228
*This information was obtained from Journal Citation Reports (ISI Web of Knowledge, Thomson Reuters, New York, NY).21
Figure 2. Time to full publication. This graph shows the time needed for abstracts to be published as full-length articles after the abstract presentation. The percentages of published manuscripts by meeting year are shown for post–abstract presentation times ranging from 0 to 90 months. Ninety percent of the abstracts were published within 46 months of presentation, and then the rate plateaued. There was no significant difference between meeting years.
Figure 3. Publication rate by specialty. The overall abstractto-publication rate is shown for each specialty of first authors who presented abstracts at the 2004-2008 ILTS meetings. There were no statistically significant differences between specialties.
members. ul Haq and Gill14 analyzed the presentation-to-publication conversion rate in peerreviewed indexed journals of a British Orthopaedic Association meeting and proposed a more rigorous abstract selection process to ensure that material could withstand peer review and have an improved chance of final publication. By striving to improve the quality but not necessarily the quantity of abstracts accepted for presentation at any scientific meeting,
one may facilitate enhanced discussion between peers, and this could lead to improved research and better meetings overall. We found a steady downward trend in the abstract-to-publication rate from the 2004 ILTS meeting (50.2%) to the 2008 meeting (30.3%). This decline was statistically significant and was possibly due to the increased number of accepted abstracts: 299 abstracts in 2004 versus 634 abstracts in 2008. Researchers’ perceptions also affect the
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outcomes of abstracts. A survey showed that abstract authors’ most common reason for not submitting fulllength manuscripts for publication included an alleged lack of time and/or low priority.1 The latter may explain why the authors of poster presentations had lower rates of publication than authors of oral presentations in this study and others1,7,8: the authors might have believed that their work was considered less important than the work of podium presenters. There is a common belief that studies selected for oral presentations are more significant and of greater quality, and this may motivate authors to seek full-length manuscript publication.1,7,8 This belief has been soundly challenged by Varghese et al.,9 who demonstrated that a significant proportion (45%) of abstracts rejected by the 2003-2005 Pediatric Orthopedic Society of North America meetings were subsequently published as full-length articles in peerreviewed journals. The importance of submitting a study with negative findings to address publication bias has been emphasized by Hopewell et al.,10 who discovered that trials with positive results were approximately 4 times more likely to be published in peer-reviewed journals than trials with negative findings. They also reported that positive findings reached publication within 4 to 5 years versus 6 to 8 years for negative findings.10 Such publication bias may affect the conclusions of meta-analyses, which depend on published manuscripts. To prevent these consequences due to possible publication bias, prospective clinical trial registries/repositories have been established to allow other researchers conducting systematic reviews to access relevant data in the United States when studies have concluded.10-16 Our study is large and comprehensive and includes all abstracts presented at 5 ILTS meetings. It is a stark exception in comparison with similar studies conducted on this topic; only 1 study published in European Heart Journal exceeded our total number of abstracts with 10,020; however, that study examined only 10% of the abstracts.6 In this study, we included the 2008 meeting as the last and most recent meeting to ensure a follow-up period of at least 4 years. This follow-up period is supported by Greenberg et al.,1 who showed that 97% of abstracts expanded into fulllength articles were published within 40 months. Indeed, we found that 90% of the ILTS abstracts expanded into full-length manuscripts were published within 46 months. To our knowledge, this study is the first to compare the abstract-to-publication rates of multiple specialties in the same society. It is difficult to find a large society meeting such as the ILTS meeting where researchers from multiple disciplines share a common interest,1 and a simple comparison of the abstract-topublication rates of leading national societies for each subspecialty may not necessarily lead to a fair comparison because of the various numbers of accepted abstracts and different selection criteria. In this work, we analyzed more than 2000 abstracts, which included a reasonable number of abstracts from sub-
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specialties less represented at the ILTS meeting (ie, anesthesiology/CCM, pathology, and radiology). We found no significant differences in the abstract-topublication rates between specialties at the ILTS meetings. Also, we discovered a positive correlation between abstracts by authors from non–Englishspeaking countries and the rate of publication. This is contradictory to the common notion that Englishspeaking authors may have an advantage in their ability to submit papers for publication in scientific journals published in English; Chan and Graham17 found a statistically significant difference (36.9% versus 18.8%) between the publication rates of countries with English as the official or widely spoken language and non–English-speaking countries. All of the indexed journals that published these manuscripts officially publish in the English language; therefore, no publication opportunity bias due to non-English languages was found. The reason for our finding is unclear; however, the result at least should encourage authors from non–English-speaking countries to continue to submit full-length manuscripts to journals published in English. Our study has several limitations. First, the minimum 4-year-follow-up period1,3,19 may still not have been long enough to identify all published articles because the time from abstract presentation to fulllength manuscript publication ranged from 1 to 85.9 months.20 We still believe that the inclusion of abstracts presented at the 2004-2008 ILTS meetings provides a reasonable picture because the longest follow-up period was 108 months, and the publication rate reached a plateau approximately 70 months after presentation. Second, some articles might have been missed during our search. One issue is that we relied on a single search engine. We trust that PubMed is the most comprehensive search engine for medical literature. The other issue is that the first authors’ last names and affiliations along with some keywords were used for the searches. We accept the critique that this strategy may not necessarily be totally reliable. However, given the sheer number of abstracts and limited logistic resources, we believe that our method gave us a reasonable chance to identify the published manuscripts. In conclusion, the full-length manuscript publication rate for the 2345 abstracts presented at the 2004-2008 ILTS meetings was 38.9%, which was comparable to the rates for other meetings. A higher rate was found for abstracts for randomized clinical trials, basic science studies, and oral presentations and for abstracts from authors from non–Englishspeaking countries. The rates did not differ between author specialties.
ACKNOWLEDGMENT The authors thank Christine M. Heiner, B.A. (scientific writer, Departments of Anesthesiology and Surgery, University of Pittsburgh School of Medicine,
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Pittsburgh, PA), for her editorial assistance with the manuscript. 11.
REFERENCES 1. Greenberg D, Wacht O, Pliskin JS. Peer review in publication: factors associated with the full-length publication of studies presented in abstract form at the annual meeting of the Society for Medical Decision Making. Med Decis Making 2008;28:938-942. 2. von Elm E, Costanza MC, Walder B, Trame`r MR. More insight into the fate of biomedical meeting abstracts: a systematic review. BMC Med Res Methodol 2003;3:12. 3. Ng L, Hersey K, Fleshner N. Publication rate of abstracts presented at the annual meeting of the American Urological Association. BJU Int 2004;94:79-81. 4. Scherer RW, Langenberg P, von Elm E. Full publication of results initially presented in abstracts. Cochrane Database Syst Rev 2007:MR000005. 5. Secil M, Ucar G, Dicle O. Scientific papers presented at the 2000-2001 European Society of Gastrointestinal and Abdominal Radiology (ESGAR) meetings: publication rates during the period 2000-2004. Eur Radiol 2007;17: 2183-2188. 6. Winnik S, Raptis DA, Walker JH, Hasun M, Speer T, Clavien PA, et al. From abstract to impact in cardiovascular research: factors predicting publication and citation. Eur Heart J 2012;33:3034-3045. 7. Cartwright R, Khoo AK, Cardozo L. Publish or be damned? The fate of abstracts presented at the International Continence Society Meeting 2003. Neurourol Urodyn 2007;26:154-157. 8. Fesperman SF, West CS, Bischoff CJ, Algood CB, Vieweg J, Dahm P. Study characteristics of abstracts presented at the annual meetings of the Southeastern Section of the American Urological Association (1996-2005). J Urol 2008;179:667-671. 9. Varghese RA, Chang J, Miyanji F, Reilly CW, Mulpuri K. Publication of abstracts submitted to the annual meeting of the Pediatric Orthopaedic Society of North America: is there a difference between accepted versus rejected abstracts? J Pediatr Orthop 2011;31:334-340. 10. Hopewell S, Loudon K, Clarke MJ, Oxman AD, Dickersin K. Publication bias in clinical trials due to statistical sig-
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nificance or direction of trial results. Cochrane Database Syst Rev 2009:MR000006. Wong CX, Wong MX, Wong NX, Sun MT, Brooks AG, Stiles MK, et al. Impact of research presentations at the annual scientific sessions of the Heart Rhythm Society. Heart Rhythm 2009;6:1345-1348. Bydder SA, Joseph DJ, Spry NA. Publication rates of abstracts presented at annual scientific meeting: how does the Royal Australian and New Zealand College of Radiologists compare? Australas Radiol 2004;48:25-28. Autorino R, Quarto G, Sio MD, Lima E, Quarto E, Damiano R, et al. Fate of abstracts presented at the World Congress of Endourology: are they followed by publication in peer-reviewed journals? J Endourol 2006; 20:996-1001. ul Haq MI, Gill I. Observational analysis of BOA freepapers (2001): from presentation to publication and comparison with the American Academy of Orthopaedic Surgeons (AAOS). Injury 2011;42:418-420. Oliveira LR, Figueiredo AA, Choi M, Ferrarez CE, Bastos AN, Netto JM. The publication rate of abstracts presented at the 2003 Urological Brazilian Meeting. Clinics (Sao Paulo) 2009;64:345-349. Akbari-Kamrani M, Shakiba B, Parsian S. Transition from congress abstract to full publication for clinical trials presented at Laser meetings. Lasers Med Sci 2008; 23:295-299. Chan JW, Graham CA. Full text publication rates of studies presented at an international emergency medicine scientific meeting. Emerg Med J 2011;28:802-803. Scherer RW, Dickersin K, Langenberg P. Full publication of results initially presented in abstracts. A metaanalysis. JAMA 1994;272:158-162. Oliver DW, Whitaker IS, Chohan DP. Publication rates for abstracts presented at the British Association of Plastic Surgeons meetings: how do we compare with other specialties? Br J Plast Surg 2003;56:158-160. Gregory TN, Liu T, Machuk A, Arneja JS. What is the ultimate fate of presented abstracts? The conversion rates of presentations to publications over a 5-year period from three North American plastic surgery meetings. Can J Plast Surg 2012;20:33-36. Journal Citation Reports. http://admin-apps.isiknowledge.com/JCR/JCR?SID51CKOdCOe46NeBC7dN73. Accessed October 2013.
SPECIAL ARTICLE
Fate of Abstracts Presented at the 2004-2008 International Liver Transplantation Society Meetings Patrick J. Hackett,1 Marina Guirguis,2 Nozomi Sakai,3 and Tetsuro Sakai1,4 Department of Anesthesiology, University of Pittsburgh Medical Center, Pittsburgh, PA; 2West Virginia University, Morgantown, WV; 3University of California Berkeley, Berkeley, CA; and 4McGowan Institute for Regenerative Medicine, University of Pittsburgh School of Medicine, Pittsburgh, PA
1
Only 20.5% to 61.6% of abstracts presented at biomedical meetings are subsequently published as full-length articles. The aim of this study was to analyze the abstract-to-publication rate of International Liver Transplantation Society (ILTS) meeting abstracts. Abstracts presented at 5 consecutive annual ILTS meetings (2004-2008) were included to ensure a minimum follow-up period of 4 years. For each abstract, a PubMed Central search was conducted with the first author’s name and affiliation along with keywords from the title. The following abstract characteristics were examined and used to obtain the abstractto-publication rate: (1) the year of presentation, (2) the presentation category (plenary session, concurrent oral presentation, or poster presentation), (3) the type of study (randomized clinical study, case report, other clinical study, or basic science study), (4) the first author’s discipline (surgery, medicine, anesthesiology/critical care medicine, pathology, radiology, or pharmacology), and (5) the location of the authors (ie, an English-speaking or non–English-speaking country). A total of 2345 abstracts (469 6 144 abstracts per meeting) were presented, and 913 of those abstracts (38.9%) were expanded into fulllength publications. It took 46 months for 90% of the abstracts to be published as full-length journal articles. The abstract-topublication rates differed with the year of abstract presentation (50.2% in 2004, 45.9% in 2005, 47.6% in 2006, 30.6% in 2007, and 30.3% in 2008; P < 0.001), with the presentation category (49.6% for plenary sessions, 48.5% for concurrent oral presentations, and 34.8% for poster presentations; P < 0.001), and with the type of study (66.7% for randomized clinical studies, 63.1% for basic science studies, 36.7% for other clinical studies, and 35.0% for case reports; P < 0.001). Abstracts from authors from non–English-speaking countries had a higher publication rate (41.1% versus 33.6%, P < 0.001). No differences C 2014 AASLD. were found between first authors’ disciplines. Liver Transpl 20:355-360, 2014. V Received November 5, 2013; accepted November 24, 2013. Presenting abstracts at national meetings allows researchers to share their scientific discoveries with a large audience, and this should lead them to submit their findings as full-length manuscripts to peer-
reviewed journals for publication. Unfortunately, not all researchers follow through with this process after the presentation of their abstracts. This failure to publish abstract data in full-length articles limits the
Abbreviations: CCM, critical care medicine; ILTS, International Liver Transplantation Society. Financial support for this work was provided solely by the institutions and departments named in the affiliations. There are no conflicts of interest to report. Tetsuro Sakai designed the study. Patrick J. Hackett, Marina Guirguis, and Nozomi Sakai collected the data. Tetsuro Sakai verified the data. Patrick J. Hackett and Tetsuro Sakai analyzed the data. Patrick J. Hackett and Tetsuro Sakai wrote the paper. Marina Guirguis and Nozomi Sakai reviewed the manuscript. This article was presented in part as a poster presentation at the 19th Annual International Congress of the International Liver Transplantation Society (Sydney, Australia, June 12-15, 2013) and at the 67th Annual PostGraduate Assembly in Anesthesiology (New York, NY, December 13-17, 2013). Address reprint requests to Tetsuro Sakai, M.D., Ph.D., Department of Anesthesiology, University of Pittsburgh Medical Center, UPMC Montefiore, N469.11, 200 Lothrop Street, Pittsburgh, PA, 15213. Telephone: 412-648-6077; FAX: 412-648-6014; E-mail: [email protected] DOI 10.1002/lt.23807 View this article online at wileyonlinelibrary.com. LIVER TRANSPLANTATION.DOI 10.1002/lt. Published on behalf of the American Association for the Study of Liver Diseases
C 2014 American Association for the Study of Liver Diseases. V
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dissemination of knowledge, the opportunity for more rigorous peer review of the findings, and ultimately could indicate the need to improve society meetings and their related specialties. The abstract to peerreviewed publication rate has been reported to be 20.5% to 61.6% for various medical specialties.1-20 In the field of liver transplantation, the annual meeting of the International Liver Transplantation Society (ILTS) has attracted a large number of multidisciplinary physicians and researchers with shared scientific interests. No prior study has investigated the abstract-to-publication rate of work presented at this meeting. The aim of this study was to analyze the fate of abstracts presented at ILTS meetings and determine any particular qualities of abstracts that were later expanded and published as full-length journal articles.
MATERIALS AND METHODS No institutional review board approval was sought for this study because all data were publicly available.
Study Materials Abstracts presented at 5 consecutive annual ILTS meetings (2004-2008) were identified in supplements to Liver Transplantation. The most recent meeting included in the study was the 2008 meeting to guarantee a minimum 4-year follow-up period and thus allow adequate time for the publication of full-length articles.1-3
Abstract Data Each abstract was categorized as follows: the year of presentation, the presentation category (plenary session, concurrent oral presentation, or poster presentation), the author’s subspecialty [surgery, medicine (hepatology, immunology, or infectious disease), anesthesiology/critical care medicine (CCM), pathology, radiology, or pharmacology], the type of study (prospective randomized study, retrospective clinical study, case report, or basic science study), and the location of the authors (ie, an English-speaking or non–English-speaking country). If an abstract listed multiple subspecialties and/or multiple affiliations in multiple countries, only the first author’s subspecialty and affiliation/country data were considered. When the subspecialty was not clearly identified (eg, liver unit), the first author’s name, the last author’s name, or both were entered into the Google search engine (last accessed on December 31, 2012) to identify the subspecialty. The countries of the authors’ affiliated institutions were later categorized as either countries with English as the dominant or official language (eg, United States, United Kingdom, Canada, Australia, New Zealand, Republic of Ireland, South Africa, India, Pakistan, Philippines, and Singapore) or non–Englishspeaking countries.
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Full-Length Manuscript Publication Search Strategy PubMed (last accessed on December 31, 2012) was used exclusively to search for publications on the basis of abstracts. The advanced search setting, PubMed Advanced Search Builder (last accessed on December 31, 2012), was used for each abstract. In the builder, the first author’s name (eg, sakai t) was entered as the author, and after the selection of the “and” linkage, the first author’s affiliation (eg, Pittsburgh) was entered as the affiliation. To narrow the search results, a specific time range including the year before the abstract presentation and the date of the search (eg, if the abstract was presented at the ILTS meeting in 2005, the range was 2004-2012) and some of the keywords in the abstract title (eg, liver or liver transplantation) were further entered. Each potential candidate manuscript was reviewed (the list of authors, the title, the abstract, and the disclosure of prior presentation of the work in the manuscript if available). When it was unclear whether an article was indeed based on the abstract of interest, the senior author of the present work (T.S.) made the final decision. Once a peer-reviewed article of interest was identified, the year of publication and the peer-reviewed journal’s name were recorded. The 5-year impact factor of each journal was identified with Journal Citation Reports (ISI Web of Knowledge, Thomson Reuters, New York, NY).21
Data Analyses The data are reported as means and standard deviations, medians and ranges, or numbers and percentages as appropriate. To compare abstract-topublication rates by the year of presentation, type of study, author’s subspecialty, presentation category, or language, Pearson’s chi-square test or Fisher’s exact test, as indicated, was used. A log-rank (MantelCox) test was used to compare the time from abstract presentation to manuscript publication between presentation years. A P value less than 0.05 was considered statistically significant. The statistical analysis was performed with GraphPad Prism 6 (GraphPad Software, Inc., La Jolla, CA).
RESULTS ILTS Meeting Abstracts The venues and dates of the ILTS meetings included in this study were as follows: the 10th ILTS meeting was held in Kyoto, Japan (June 9-12, 2004); the 11th ILTS meeting was held in Los Angeles, CA (July 2023, 2005); the 2006 Joint International Congress of the ILTS, the European Liver and Intestinal Transplant Association, and the Liver Intensive Care Group of Europe was held in Milan, Italy (May 3-6, 2006); the 13th ILTS meeting was held in Rio de Janeiro, Brazil (June 20-23, 2007); and the 2008 Joint
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International Congress of the ILTS, the European Liver and Intestinal Transplant Association, and the Liver Intensive Care Group of Europe was held in Paris, France (July 9-12, 2008). A total of 2345 abstracts were presented; there were 469 6 144 abstracts per meeting (299 abstracts in 2004, 338 in 2005, 515 in 2006, 561 in 2007, and 634 in 2008). The majority of the abstracts were presented as posters (68.5% 6 8.4% as poster presentations, 26.4% 6 7.8% as concurrent oral presentations, and 5.1% 6 0.9% at plenary sessions), and most of the abstracts were based on retrospective clinical studies (81.2% 6 4.4% for retrospective clinical studies, 9.4% 6 2.4% for case reports, 7.0% 6 1.1% for basic science studies, and 2.5% 6 2.0% for prospective randomized studies). Surgery was the main subspecialty of the first authors (74.5% 6 4.0% in surgery, 12.8% 6 2.2% in medicine, 8.2% 6 1.8% in anesthesiology/CCM, 2.0% 6 1.9% in pathology, 1.5% 6 0.7% in radiology, 0.6% 6 0.3% in pharmacology, and 0.2% 6 0.6% in other subspecialties). Authors from English-speaking countries were responsible for 30.1% 6 7.2% of the abstracts, and authors from non– English-speaking countries were responsible for 69.9% 6 7.2%. The nations of the affiliated institutions of the first authors were as follows: the United States (n 5 532 or 26.7%), Italy (n 5 272 or 11.6%), Brazil (n 5 226 or 9.6%), South Korea (n 5 177 or 7.5%), Japan (n 5 176 or 7.5%), Spain (n 5 115 or 4.9%), France (n 5 110 or 4.7%), Germany (n 5 109 or 4.6%), United Kingdom (n 5 80 or 3.4%), Taiwan (n 5 72 or 3.1%), China (n 5 55 or 2.3%), Netherlands (n 5 54 or 2.3%), Turkey (n 5 50 or 2.1%), Poland (n 5 42 or 1.8%), Canada (n 5 37 or 1.6%), Saudi Arabia (n 5 25 or 1.1%), Argentina (n 5 24 or 1.0%), Australia (n 5 22 or 0.9%), Austria (n 5 21 or 0.9%), Egypt (n 5 19 or 0.8%), Belgium (n 5 18 or 0.8%), India (n 5 13 or 0.6%), Finland (n 5 11 or 0.5%), Switzerland (n 5 11 or 0.5%), Sweden (n 5 11 or 0.5%), and 20 other countries (a total of 63 abstracts with fewer than 10 abstracts from each country).
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Figure 1. Abstract-to-publication rate. This stacked column graph shows the total number of abstracts presented at the 2004-2008 ILTS meetings, and each column is divided into abstracts with published full-length manuscripts and abstracts without published full-length manuscripts. The publication rates are shown beneath the years; the combined publication rate was 38.9%. A statistically significant decline (P < 0.001) in the rate from 2004 to 2008 was noted.
(150/299 abstracts) for the 2004 ILTS meeting, 45.9% (155/338) for the 2005 ILTS meeting, 47.6% (245/515) for the 2006 ILTS meeting, 30.7% (172/ 561) for the 2007 ILTS meeting, and 30.3% (192/ 634) for the 2008 ILTS meeting. The rates were also higher for abstracts presented at plenary sessions and concurrent oral sessions (49.6% for plenary session abstracts, 48.5% for concurrent oral session abstracts, and 34.8% for poster session abstracts; P < 0.001) and for randomized clinical studies and basic science studies (66.7% for randomized clinical studies, 63.1% for basic science studies, 36.7% for retrospective clinical studies, and 35.0% for case reports; P < 0.001). Abstracts from authors from non– English-speaking countries had a higher publication rate (41.1% versus 33.6%, odds ratio 5 1.4, 95% confidence interval 5 1.15-1.66, P < 0.001). No differences were found between the disciplines of first authors (Fig. 3).
Abstract-to-Publication Rate Nine hundred thirteen of the 2345 abstracts (38.9%) were ultimately published as full-length, peerreviewed journal articles (Fig. 1). A list of top 20 journals is provided in Table 1. The top 6 journals in which the ILTS abstracts were published as fulllength articles were Liver Transplantation (264 abstracts), Transplant Proceedings (139), Transplantation (86), American Journal of Transplantation (70), Transplant International (61), and Clinical Transplantation (42). Ninety percent of the abstracts were published as full-length articles within 46 months after abstract presentation. No statistical difference was found between the presentation years for the time from abstract presentation to full-length manuscript publication (P 5 0.73; Fig. 2). The abstract-to-publication rates varied significantly (P < 0.001) with the year of presentation: 50.2%
DISCUSSION There were 2345 abstracts presented at 5 consecutive annual ILTS meetings (2004-2008), and 38.9% were published as full-length articles within the minimum 4-year follow-up period; this rate is comparable to other reported rates.1-20 Several abstract characteristics were found to be associated with a higher publication rate, including oral presentations, randomized controlled clinical trials, and basic science studies, and this has been supported by similar studies.2,4,5 The importance of publishing full-length manuscripts expanded from meeting abstracts cannot be overemphasized. The full-length manuscript publication rate of meeting abstracts not only illustrates the quality of research conducted by an institution’s investigators but also portrays the activity and reputation of a particular scientific meeting and its society
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TABLE 1. Top 20 Journals That Published Full-Length Manuscripts of Abstracts Presented at ILTS Meetings (20042008) Journal Name Liver Transplantation Transplant Proceedings Transplantation American Journal of Transplantation Transplant International Clinical Transplantation Hepatogastroenterology Pediatric Transplant Surgery Journal of Surgical Research Digestive Disease and Sciences Anesthesia and Analgesia Annals of Transplantation Journal of Hepatology Annals of Surgery American Surgeon Critical Care Medicine Gastroenterology Journal of the American College of Surgeons World Journal of Surgery
Publications (n)
5-Year Impact Factor*
264 139 86 70 61 42 19 18 13 13 12 11 10 10 8 6 6 6 6 6
3.944 0.952 3.781 6.192 3.155 1.884 0.774 1.500 3.373 2.018 2.260 3.300 0.815 9.858 6.329 0.918 6.124 12.821 4.500 2.228
*This information was obtained from Journal Citation Reports (ISI Web of Knowledge, Thomson Reuters, New York, NY).21
Figure 2. Time to full publication. This graph shows the time needed for abstracts to be published as full-length articles after the abstract presentation. The percentages of published manuscripts by meeting year are shown for post–abstract presentation times ranging from 0 to 90 months. Ninety percent of the abstracts were published within 46 months of presentation, and then the rate plateaued. There was no significant difference between meeting years.
Figure 3. Publication rate by specialty. The overall abstractto-publication rate is shown for each specialty of first authors who presented abstracts at the 2004-2008 ILTS meetings. There were no statistically significant differences between specialties.
members. ul Haq and Gill14 analyzed the presentation-to-publication conversion rate in peerreviewed indexed journals of a British Orthopaedic Association meeting and proposed a more rigorous abstract selection process to ensure that material could withstand peer review and have an improved chance of final publication. By striving to improve the quality but not necessarily the quantity of abstracts accepted for presentation at any scientific meeting,
one may facilitate enhanced discussion between peers, and this could lead to improved research and better meetings overall. We found a steady downward trend in the abstract-to-publication rate from the 2004 ILTS meeting (50.2%) to the 2008 meeting (30.3%). This decline was statistically significant and was possibly due to the increased number of accepted abstracts: 299 abstracts in 2004 versus 634 abstracts in 2008. Researchers’ perceptions also affect the
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outcomes of abstracts. A survey showed that abstract authors’ most common reason for not submitting fulllength manuscripts for publication included an alleged lack of time and/or low priority.1 The latter may explain why the authors of poster presentations had lower rates of publication than authors of oral presentations in this study and others1,7,8: the authors might have believed that their work was considered less important than the work of podium presenters. There is a common belief that studies selected for oral presentations are more significant and of greater quality, and this may motivate authors to seek full-length manuscript publication.1,7,8 This belief has been soundly challenged by Varghese et al.,9 who demonstrated that a significant proportion (45%) of abstracts rejected by the 2003-2005 Pediatric Orthopedic Society of North America meetings were subsequently published as full-length articles in peerreviewed journals. The importance of submitting a study with negative findings to address publication bias has been emphasized by Hopewell et al.,10 who discovered that trials with positive results were approximately 4 times more likely to be published in peer-reviewed journals than trials with negative findings. They also reported that positive findings reached publication within 4 to 5 years versus 6 to 8 years for negative findings.10 Such publication bias may affect the conclusions of meta-analyses, which depend on published manuscripts. To prevent these consequences due to possible publication bias, prospective clinical trial registries/repositories have been established to allow other researchers conducting systematic reviews to access relevant data in the United States when studies have concluded.10-16 Our study is large and comprehensive and includes all abstracts presented at 5 ILTS meetings. It is a stark exception in comparison with similar studies conducted on this topic; only 1 study published in European Heart Journal exceeded our total number of abstracts with 10,020; however, that study examined only 10% of the abstracts.6 In this study, we included the 2008 meeting as the last and most recent meeting to ensure a follow-up period of at least 4 years. This follow-up period is supported by Greenberg et al.,1 who showed that 97% of abstracts expanded into fulllength articles were published within 40 months. Indeed, we found that 90% of the ILTS abstracts expanded into full-length manuscripts were published within 46 months. To our knowledge, this study is the first to compare the abstract-to-publication rates of multiple specialties in the same society. It is difficult to find a large society meeting such as the ILTS meeting where researchers from multiple disciplines share a common interest,1 and a simple comparison of the abstract-topublication rates of leading national societies for each subspecialty may not necessarily lead to a fair comparison because of the various numbers of accepted abstracts and different selection criteria. In this work, we analyzed more than 2000 abstracts, which included a reasonable number of abstracts from sub-
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specialties less represented at the ILTS meeting (ie, anesthesiology/CCM, pathology, and radiology). We found no significant differences in the abstract-topublication rates between specialties at the ILTS meetings. Also, we discovered a positive correlation between abstracts by authors from non–Englishspeaking countries and the rate of publication. This is contradictory to the common notion that Englishspeaking authors may have an advantage in their ability to submit papers for publication in scientific journals published in English; Chan and Graham17 found a statistically significant difference (36.9% versus 18.8%) between the publication rates of countries with English as the official or widely spoken language and non–English-speaking countries. All of the indexed journals that published these manuscripts officially publish in the English language; therefore, no publication opportunity bias due to non-English languages was found. The reason for our finding is unclear; however, the result at least should encourage authors from non–English-speaking countries to continue to submit full-length manuscripts to journals published in English. Our study has several limitations. First, the minimum 4-year-follow-up period1,3,19 may still not have been long enough to identify all published articles because the time from abstract presentation to fulllength manuscript publication ranged from 1 to 85.9 months.20 We still believe that the inclusion of abstracts presented at the 2004-2008 ILTS meetings provides a reasonable picture because the longest follow-up period was 108 months, and the publication rate reached a plateau approximately 70 months after presentation. Second, some articles might have been missed during our search. One issue is that we relied on a single search engine. We trust that PubMed is the most comprehensive search engine for medical literature. The other issue is that the first authors’ last names and affiliations along with some keywords were used for the searches. We accept the critique that this strategy may not necessarily be totally reliable. However, given the sheer number of abstracts and limited logistic resources, we believe that our method gave us a reasonable chance to identify the published manuscripts. In conclusion, the full-length manuscript publication rate for the 2345 abstracts presented at the 2004-2008 ILTS meetings was 38.9%, which was comparable to the rates for other meetings. A higher rate was found for abstracts for randomized clinical trials, basic science studies, and oral presentations and for abstracts from authors from non–Englishspeaking countries. The rates did not differ between author specialties.
ACKNOWLEDGMENT The authors thank Christine M. Heiner, B.A. (scientific writer, Departments of Anesthesiology and Surgery, University of Pittsburgh School of Medicine,
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Pittsburgh, PA), for her editorial assistance with the manuscript. 11.
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