Article and journal impact factor in various scientific fields

BackgroundWe tried to provide the scientific community with data to answer the following simple question: What proportion of publications in the various scientific fields is published in journals with impact factor above the median and mean values of the distribution of journal impact factor?MethodsWe analyzed and compared the distribution of the impact factor data reduced to the unit of science publication, the article. We calculated the proportion of articles published in journals with impact factor above the journal mean impact factor, journal median impact factor, and article mean impact.ResultsFor all categories examined, at the article level, the mean impact factor was higher than the median (by 13.7% to 500% for the various scientific categories). The mean impact factor of journals was considerably lower than the mean impact factor of articles (by 0.3 to 6.4 units). The proportion of articles that were published in journals with impact factor above the journals’ median impact factor was well above 50% in 17 of 19 scientific fields examined (all except mathematics and computer science).SignificanceOur analysis shows that in most scientific fields examined, it is quite easier to publish an article in the top 50% of journals (based on impact factor calculations) than it is for the article to be included in the top 50% of published articles (based on the assumption made regarding the article’ impact factor).     

ORIGINAL ARTICLE: Comparison of the distribution of citations received by articles published in high,moderate, and low impact factor journals in clinical medicine

Background: Whether the journal impact factor (JIF) indicator reflects the number of citations to an average article of a journal in different subject categories is controversial. We sought to further investigate this issue in general and internal medicine journals. Methods: We selected to evaluate three journals of the above subject category, in each of three different JIF levels (high: 15.5–28.6, moderate: 4.4–4.9 and low: 1.6). Using the Scopus database, we retrieved the original research articles (after detailed screening) and review articles (as classified by Scopus) that were published in the selected journals in 2005 along with the number of citations they received in 2006 and 2007. We pooled the citations for articles of the same type in journals with the same JIF level into distinct variables. Results: There was no marked association between the distribution of citations per article published in general medical journals and their JIF. All distributions studied were skewed to the right (higher number of citations). Specifically, 16–22% of the original research articles accounted for 50% of the total citations to this type of article for all three categories of studied journals; 34–37% of original research articles accounted for 75% of citations. The respective values for review articles were 12–18% and 29–39%. Conclusion: The distribution of citations received by articles published in high, moderate and low impact factor journals in clinical medicine seems similar. The JIF is not an accurate indicator of the citations the average article receives; articles published in low impact factor journals can still be highly cited and vice versa.     

《中华肝脏病杂志》近5年学术质量及影响力综合分析

目的通过对近5年《中华肝脏病杂志》载文，引文、学术质量及影响力情况调查分析，以促进《中华肝脏病杂志》及其他相关杂志学术质量及导向性的提高，更好地指导我国肝病科研和临床工作。方法检索《中华肝脏病杂志》1999-2003年载文中原著论文、论文摘要、评(综)述、经验交流等论文，并对作者来源地区、载文及引文信息进行统计分析；对标志杂志学术质量及影响力的总被引频次、影响因子、即年指标、他引总引比、基金项目等指标进行秩和比分析。结果(1)该刊作者来自全国26个省市；大部分作者来自我国医学相关高等院校、省及省级以上医疗机构，1999-2003年刊载论文中，来自高等院校的论文分别占48.8％、49.3％、60.8％、72.2％、71.7％；来自省级及以上医疗机构的论文分别占16.7％、30.3％、24.7％、12.7％、15．2％。少量作者来自地市级及以下医疗机构，分别占34．5％、20.4％、14.5％、15.1％、13．1％。来自海外的作者数逐年增多。(2)年度载文量由248／年增加到336／年；信息充分度由1.21增加到2.26，信息量略有下降。(3)年参考文献量由702增加到1744，外文引文能力由76．1％增加到81．2％。(4)1999-2001年学术质量及影响力略有波动，各指标加权秩和比分别为0.3417、0．2750、0.5000，以后一直维持在0．5000的较高水平。结论该刊作者群覆盖了我国大部分地区；年度载文量和信息充分度增加；引文能力呈自然状态，基本稳定，外文引文能力逐年增加；学术质量在国内一直维持在较高水平。     

Footprint and Imprint: An Ecologic Time-Trend Analysis of Cardiovascular Publications in General and Specialty Journals

Studies have demonstrated strong associations between publication source and citations, as well as investigatory analysis of collaboration effects, in general and medical literature, but are limited to specific journals or short duration of time. This study sought to analyze time trends in cardiovascular research publications in leading general and specialty journals and to determine the association between collaboration and citation index. Cardiovascular publications were retrieved from Web of Knowledge by a cardiovascular bibliometric filter, and annual publication volumes in 8 general and specialty journals were compared. Univariable linear regression models were used to determine global and journal-specific trends for overall publication, cardiovascular publication, proportion of cardiovascular publication, collaboration, and citations. Cardiovascular publications increased (1999 to 2008) by 36% and number of sources by 74%. Volume increased in European Heart Journal (beta: 18.4, 95% confidence interval [CI]: 10.6 to 26.3) and decreased in Circulation (beta: −42.9, 95% CI: −79.3 to −6.5), Annals of Internal Medicine (beta: −1.9, 95% CI: −3.5 to −0.3), and Lancet (beta: −11.2, 95% CI: −14.7 to −7.8). Number of contributing countries increased in 3 journals: BMJ (beta: 0.8, 95% CI: 0.2 to 1.5), European Heart Journal (beta: −1.2, 95% CI: 0.8 to 1.7), and New England Journal of Medicine (beta: 1.6, 95% CI: 0.6 to 2.7). Fraction of collaborative publications increased (beta: 1.1 to 2.9) in all but Annals of Internal Medicine. Collaboration was associated with a higher median actual citation index (p < 0.0001). We found increasing trends in collaboration and citation in both general and specialty journals. Contribution by country in selected journals was disproportionate and under-represents total cardiovascular research in low- and middle-income countries.     

Spanish production of research articles on diagnostic imaging in cardiology and radiology (1994-1998)

INTRODUCTION AND OBJECTIVES: The aim of this study was to evaluate the production of research papers by Spanish authors on diagnostic imaging published in the official journals of two Spanish scientific societies (Revista Espa?ola de Cardiología and Radiología) between 1994 and 1998, and to compare publication rates with those of research papers published in foreign cardiological and radiological journals included in Journal Citation Reports. MATERIAL AND METHOD: Specific search profiles were devised to retrieve items from the Indice Médico Espa?ol (IME) and MEDLINE databases. The impact factor for non-Spanish journals devoted to different specialties was normalized for the number of papers published. RESULTS: 967 articles were analyzed (301 on cardiac imaging, 666 on radiology). In the former specialty, 50.5% of the items were published in Revista Espa?ola de Cardiología, and in the latter, 55.1% were published in Radiología (no statistically significant difference). Impact factor was 2.46 for cardiology and 0.98 for radiology. The percentage of papers published in journals ranked in the top quartile according to impact factor was 38.6% (cardiology) and 17.2% (radiology); the difference was significant at P< .0001. DISCUSSION: Although a tendency for radiologists to publish increasingly in foreign radiological journals has been observed, Spanish cardiologists and radiologists publish more than 50% of their research papers on diagnostic imaging in the official journals of their national societies. The differences in the percentage of articles by Spanish authors published in international specialty journals ranked in the first quartile (twice as great for cardiology as for radiology) suggests that Spanish radiologists are joining the scientific international community at a slower rate than Spanish cardiologists.     

Medline-based bibliometric analysis of gastroenterology journals between 2001 and 2007

AIM： To analyze the MEDLINE-indexed publications in gastroenterology specialty journals from 2001 to 2007. Special attention was paid to specific types of articles, the number of publications for individual authors and the author count in each journal.
METHODS： The bibliographic entries of papers belonging to journals listed under the subject heading of＂gastroenterology＂ were downloaded from MEDLINE on the PubMed web site. The analysis was limited to journal articles published between January 1, 2001 and December 31, 2007. The analytical dimensions of an article included journal, publication year, publication type, and author name （the last name and initials）.
RESULTS： According to MEDLINE, 81561 articles were published in 91 gastroenterology journals from 2001 to 2007. The number of articles increased from 9447 in 2001 to 13340 in 2007. Only 12 journals had more than 2000 articles indexed in MEDLINE. The ＂World Journal of Gastroenterology＇ had the largest number of publications （5684 articles）, followed by ＂Hepato-Gastroenterology＇ （3036） and ＂Gastrointestinal Endoscopy＂ （3005）. Of all the articles published, reviews accounted for 17.2% and case reports for 15.4%. Only 3739 randomized controlled trials （4.6% of all articles） were published and their annual number increased from 442 in 2001 to 572 in 2007. Among 141741 author names appearing in the articles of gastroenterology journals, 92429 had published only in one journal, 22585 in two journals, 9996 in three journals, and 16731 in more than three journals. The ＂World Journal of Gastroenterology＂ had the greatest number of authors （17838）,followed by ＂Gastroenterology＂ （12 770）, ＂Digestive Diseases and Sciences＂ （11395）, ＂American Journal of Gastroenterology＂ （10889）, and ＂Hepatology＂ （ 10 588）.
CONCLUSION： Global gastroenterology publications displayed a continuous growth in the new millennium. The change was most striking in certain journals. Regular bibliometric analyses on the trends and specific topics would help researchers publish more efficiently and allow editors to adjust the policy more accurately.     

Funding source and conflict of interest disclosures by authors and editors in gastroenterology specialty journals

INTRODUCTION: Declarations of conflicts of interest have received considerable scrutiny in recent years. AIM: To determine if the leading gastroenterology journals had a formal conflict of interest disclosure policy and the extent to which this policy was followed by reporting of funding sources and potential conflicts of interests of the authors and editors of published studies. METHODS: We examined original articles and editorials in 12 leading journals (determined by impact factor) devoted to gastroenterology and hepatology. We examined the editorial policy of the journal (if available) on the Web site of the journal or in print versions of the journal and contacted the journal for further information on editorial policies. RESULTS: A total of 1,114 original articles and 154 editorials were evaluated from 12 journals. The source of funding for a study was disclosed in 19-99% of the articles examined with only one journal reporting the funding source (or absence of funding) in over 90% of articles studied. A potential conflict of interest was present in 0-13% of original articles and 0-33% of editorials. Only 2 of 12 (17%) journals publicly disclosed the conflicts of interest of the editors to the reader and only 3 (25%) had a formal method for handling editors' conflicts of interest. CONCLUSIONS: Editors of gastroenterology and hepatology journals have been slow to implement guidelines for the disclosure of their own conflicts of interest. Disclosure of funding sources and conflicts of interest of authors is variable despite the presence of conflict of interest policies at most journals.     

The current status of hepatobiliary and pancreatic surgical literature

Background. A rapidly growing knowledge base has evolved describing recently developed diagnostic and therapeutic techniques in the management of hepatic-pancreatic-biliary (HPB) disease. As such, it is expected that the current literature should reflect these trends in the emerging specialty of HPB surgery. Methods. The content of 10 leading surgical journals was assessed for the separate years 1998 and 2002 using a combination of hand searching and Medline searching using the Pubmed search engine. Data retrieved for each journal included: total number/type of publication, specialty category, disease focus and comment on surgical technique. Results. A total of 817 HPB articles were reviewed (386 in 1998,431 in 2002). Half of the journals showed an absolute increase in the number of HPB articles published; the largest increase was for Surgery (12%; 2002: 64/431; 1998: 10/386, p<0.0001), while the British Journal of Surgery displayed the greatest decrease (11%; 2002: 56/431; 1998: 94/386, p<0.0001). Publication by the nature of disease revealed that overall, there was a trend towards a greater volume of publications on malignant disease over the 4-year period (1998: 41%; 2002: 56%). Furthermore, 91% (10/11) of articles published by the Canadian Journal of Surgery related to benign disease; while almost all (97%) of the articles published by the Annals of Surgical Oncology were on malignant disease. There was a difference in the pathology focus for each sub-category of HPB topics. Fifty percent (150/302) of the articles on hepatic disease focused on malignancy, as compared with 46% (124/272) of those on pancreatic disease and 21% (44/213) of those on biliary disease. A comment on surgical technique was uniform across all categories (47% hepatic, 48% pancreatic and 44% biliary). Discussion. Articles dealing with HPB topics are published widely across all reviewed journals. Although the absolute number of HPB articles published increased over a 4-year period, there is significant variability in overall topics and focus of publication between journals. Overall, there was a uniform paucity of basic science articles, evidence-based reviews and/or meta-analyses, indicating an opportunity for growth in the future.     

Measuring the quality of journals and journal articles: the impact factor tells but a portion of the story

Much emphasis has been placed on the IMPACT FACTOR, a measure of journal article citation rates used as a surrogate marker of both journal and article quality. There is little doubt that the impact factor is an important audit of journal article usage, as it in essence provides a measure of the level of peer attention being given to articles within journals and (by extrapolation) of the level of attention being given to the journal containing those articles. However, the impact factor has its limitations and only tells a very small fraction of the overall story regarding the utility of journals and the articles within them. In addition, the impact factor can be easily manipulated. The current article includes a brief review of the current and past uses and abuses of the impact factor and describes some of its strengths and limitations. In addition, a review of past publications, primarily from this journal, has been undertaken to help show the potential use of alternative measures of journal utility, such as Internet-based journal sessions and article downloads. The evaluation of previously published articles also helps serve to illustrate, by example, some of the limitations to the use of the impact factor as the sole determinant of a journal's "quality."     

Errors in medical literature: not a question of impact

The editorial and peer-review processes should guarantee readers as to the reliability of published data. The first step of these processes is to check for errors. The aim of our study was to look for the presence of objective errors in consecutive articles published on three of the most authoritative clinical journals. Two reviewers evaluated the presence of any error in 200 consecutive original articles containing at least two tables, allowing a reanalysis of the data, published between October 2010 and April 2011. Error was considered any action different from what was planned. Errors were listed as: methodological, numerical and slips. They were considered as severe if numbers in the abstract were completely different from numbers reported in the full text. Among the 125 articles included in the study, 102 (82 %, 95 % CI 74–88 %) contained some kind of error, even multiple. Nine articles (7 %, 95 % CI 3–13 %) contained one slip, 92 articles (74 %, 95 % CI 65–81 %) contained at least one numerical error, and 22 articles (18 %, 95 % CI 11–25 %) contained one methodological error. Five articles (4 %, 95 % CI 1–9 %) contained one serious error. None of the errors retrieved (0 %, 95 % CI 0–2 %) would have changed the results of the studies. Most of the articles published in the most important medical journals present mistakes. Our results could be a clue to editorial and peer review systems system weaknesses. A debate within the scientific medical community about these systems, and possible alternative adjustments are needed.     

Citation classics in acute pancreatitis

Background/ObjectivesThe number of times an article is cited in scientific journals reflects its impact on a specific biomedical field or specialty and reflects the impact of the authors' creativity. Our purpose was to characterize the most frequently cited articles about acute pancreatitis.MethodsWe utilized the 2010 edition of Journal Citation Reports and Social Sciences Citation Index database to determine the most frequently cited articles published after 1956. The 100 most frequently cited articles were selected. Articles were evaluated for several characteristics including number of citations, publication time, country of origin, institution, journal, publication type of article and authorship.ResultsThe most frequently cited article received 1281 citations and the least frequently cited article received 163 citations, with a mean of 266.65 citations per article. These citation classics were published in 31 high-impact journals, led by Gastroenterology. Of the 100 articles, 56 were clinical observational studies, 20 concerned basic science and 15 were review articles. The articles originated from 16 countries, with the United States contributing 47 articles; 56 institutions produced these 100 top-cited articles, led by University of Ulm (9 publications) and New York University (9 publications); 23 persons authored 3 or more of the top-cited articles led by Imrie (10 publications).Conclusion“Citation classics” about acute pancreatitis are detected in both experimental and clinical research field, which provide a historical perspective on the scientific progress and allow for recognition of important advances in this specialty.     

科学引文索引源期刊中肝脏病学期刊及影响因子统计分析

目的统计分析科学引文索引（SCI）源期刊中的肝病相关期刊的影响因子，促进我国肝病科研及相关期刊发展。方法检索SCI源期刊中肝病学相关科技期刊，并对其影响因子等情况进行统计分析。结果19种期刊分别由6个国家出版，其中美国出版有11种，占了SCI收录的胃肠和肝病学期刊总数的58％，19种期刊中有11种被ScienceDirect（Elsevier）、Blackwell和Wiley期刊全文数据库收录。该学科中影响因子最高的期刊是Gastroenterology，影响因子为13．092，其次是Hepatology，影响因子是10．416；在19种期刊中影响因子超过2的有12种。结论以上12种期刊可视为本学科的核心期刊，国内肝病学研究及相关医学期刊需进一步提高国际化程度。     

Methodological issues in trials assessing primary prophylaxis of venous thrombo-embolism.

AIMS: Many trials have been conducted to assess the efficacy of various strategies in the prevention of venous thrombo-embolism (VTE). Some of these trials have been subject to methodological criticisms. We aimed to assess the methodological issues raised by VTE trials. METHODS AND RESULTS: We searched MEDLINE and the Cochrane Central Register of Controlled Trials for articles assessing primary thromboprophylaxis published between 1994 and 2003 in 60 general medical and specialty journals. A total of 77 articles were analysed by two independent reviewers using a list of items. No primary endpoint was defined in 20% of trials. Although the primary endpoint was collected before day 15 in 75% of trials, there were >/=20% missing data in 56% of articles and >/=30% in 24.2% of articles. The rate of missing data was 23.7+/-9.7% in studies using venography-detected deep-vein thrombosis as an endpoint compared with 5.6+/-6.0% in studies using other endpoints. Among the 47 superiority trials, 27 (57.4%) reported an intention-to-treat (ITT) analysis, but only 10 (21.3%) reported an analysis that complied with this principle. These results were consistent when limiting the analysis to articles published in high-impact journal (impact factor more than 5). CONCLUSION: Recent randomized controlled trials assessing prophylactic regimens in VTE have important methodological limitations in terms of primary endpoints, missing data, and compliance with the ITT principle. These methodological shortcomings should be addressed when planning future trials.