von Elm Erik, Poglia Greta, Walder Bernhard, Tramèr Martin R
Division of Anesthesiology, Department of Anesthesiology, Pharmacology, and Surgical Intensive Care, Geneva University Hospitals, Geneva, Switzerland.
JAMA. 2004 Feb 25;291(8):974-80. doi: 10.1001/jama.291.8.974.
Duplicate publication is publication of an article that overlaps substantially with an article published elsewhere. Patterns of duplication are not well understood.
To investigate duplication patterns and propose a decision tree for classification.
We searched a comprehensive list of systematic reviews (1989 through August 15, 2002) in anesthesia and analgesia that is accessible on the Internet. We selected published full articles of duplicates that had been identified in these systematic reviews. Abstracts, letters, or book chapters were excluded.
Authors of 56 (40%) of 141 systematic reviews acknowledged identification of duplicates. Duplication patterns were identified independently by all investigators comparing samples and outcomes of pairs of duplicates and main articles. Information on cross-reference, sponsorship, authorship, and publication characteristics was extracted from the articles.
The 56 systematic reviews included 1131 main articles (129 337 subjects) and excluded 103 duplicates (12 589 subjects) that originated from 78 main articles. Sixty articles were published twice, 13 three times, 3 four times, and 2 five times. We identified 6 duplication patterns: (1A) identical samples and identical outcomes (21 pairs); (1B) same as 1A but several duplicates assembled (n = 16); (2) identical samples and different outcomes (n = 24); (3A) increasing sample and identical outcomes (n = 11); (3B) decreasing sample and identical outcomes (n = 11); (4) different samples and different outcomes (n = 20). The prevalence of covert duplicate articles (without a cross-reference to the main article) was 5.3% (65/1234). Of the duplicates, 34 (33%) were sponsored by the pharmaceutical industry, and 66 (64%) had authorship that differed partly or completely from the main article. The median journal impact factor was 1.8 (range, 0.1-29.5) for duplicates and 2.0 (range, 0.4-29.5) for main articles (P =.13). The median annual citation rate was 1.7 (range, 0-27) for duplicates and 2.1 (range, 0-31) for main articles (P =.45). The median number of authors was 4 (range, 1-14) for duplicates and 4 (range, 1-15) for corresponding main articles (P =.02). The median delay in publication between main articles and duplicates was 1 year (range, 0-7 years).
Duplication goes beyond simple copying. Six distinct duplication patterns were identified after comparing study samples and outcomes of duplicates and corresponding main articles. Authorship was an unreliable criterion. Duplicates were published in journals with similar impact factors and were cited as frequently as main articles.
重复发表是指一篇文章与其他地方发表的文章大量重叠。重复的模式尚未得到很好的理解。
调查重复模式并提出一个分类决策树。
我们在互联网上搜索了一份全面的麻醉与镇痛系统评价列表（1989年至2002年8月15日）。我们选择了这些系统评价中已识别出的重复文章的全文发表版本。排除摘要、信件或书籍章节。
141项系统评价中的56项（40%）的作者承认识别出了重复文章。所有研究人员通过比较重复文章对与主要文章的样本和结果，独立识别重复模式。从文章中提取了关于交叉引用、资助、作者身份和发表特征的信息。
这56项系统评价包括1131篇主要文章（129337名受试者），并排除了来自78篇主要文章的103篇重复文章（12589名受试者）。60篇文章发表了两次，13篇发表了三次，3篇发表了四次，2篇发表了五次。我们识别出6种重复模式：（1A）相同样本和相同结果（21对）；（1B）与1A相同，但有几篇重复文章合并（n = 16）；（2）相同样本和不同结果（n = 24）；（3A）样本增加且结果相同（n = 11）；（3B）样本减少且结果相同（n = 11）；（4）不同样本和不同结果（n = 20）。隐性重复文章（未交叉引用主要文章）的比例为5.3%（65/1234）。在重复文章中，34篇（33%）由制药行业资助，66篇（64%）的作者与主要文章部分或完全不同。重复文章的期刊影响因子中位数为1.8（范围：0.1 - 29.5），主要文章的为2.0（范围：0.4 - 29.5）（P = 0.13）。重复文章的年引用率中位数为1.7（范围：0 - 27），主要文章的为2.1（范围：0 - 31）（P = 0.45）。重复文章的作者数量中位数为4（范围：1 - 14），相应主要文章的为4（范围：1 - 15）（P = 0.02）。主要文章与重复文章之间的发表延迟中位数为1年（范围：0 - 7年）。
重复不仅仅是简单的抄袭。在比较重复文章与相应主要文章的研究样本和结果后，识别出了六种不同的重复模式。作者身份是一个不可靠的标准。重复文章发表在影响因子相似的期刊上，被引用的频率与主要文章相同。
