Bloomberg School of Public Health, The Johns Hopkins University, Baltimore, Maryland.
Welch Medical Library, The Johns Hopkins University, Baltimore, Maryland.
JAMA Netw Open. 2020 Dec 1;3(12):e2027104. doi: 10.1001/jamanetworkopen.2020.27104.
Duplicate publications of randomized clinical trials are prevalent in the health-related literature. To date, few studies have assessed the interaction between duplicate publication and the language of the original publication.
To assess the existence of duplicate publication and the extent to which duplicate publication is associated with the language of the original publication.
DESIGN, SETTING, AND PARTICIPANTS: In this retrospective cohort study, eligible randomized clinical trials were retrieved from trial registries, and bibliographic databases were searched to determine their publication status. Eligible randomized clinical trials were for drug interventions from January 1, 2008, to December 31, 2014. The search and analysis were conducted from March 1 to August 31, 2019. The trial registries were either primary registries recognized by the World Health Organization or the Drug Clinical Trial Registry Platform sponsored by the China Food and Drug Administration.
Individual randomized clinical trials with positive vs negative results.
Journal articles were classified as main articles (determined by largest sample size and longest follow-up among all journal articles derived from that randomized clinical trial) and duplicates. The duplicates were classified into 4 types: (1) unreferenced subgroup analysis (article did not disclose itself as a subgroup analysis or reference its main article); (2) unreferenced republication (article did not disclose itself as a replicate of the main article or reference it); (3) unreferenced interim analysis (article did not disclose itself as an interim analysis or reference its main article); and (4) partial duplicate (article did not disclose its sharing a subset of participants with other articles or reference them).
Among 470 randomized clinical trials published by August 2019 as journal articles, 55 (11.7%) had 75 duplicates, of which 53 (70.7%) were cross-language duplicates. Of the 75 duplicates, 33 (44.0%) were unreferenced republications, 25 (33.3%) unreferenced subgroup analyses, 15 (20.0%) unreferenced interim analyses, and 2 (2.7%) partial duplicates. When the main article of a randomized clinical trial was published in Chinese, those with positive findings were 2.48 (95% CI, 1.08-5.71) times more likely to have subsequent duplicate publication than those with negative findings.
In this study, most duplicates were cross-language duplicates and the most common type was unreferenced republication of the main article. Duplicate publication bias exists when the main articles of randomized clinical trials were published in Chinese, potentially misleading readers and compromising journals and evidence synthesis.
重复发表的随机临床试验在与健康相关的文献中很普遍。迄今为止，很少有研究评估重复发表与原始出版物语言之间的相互作用。
评估重复发表的存在以及重复发表与原始出版物语言之间的关联程度。
设计、设置和参与者：在这项回顾性队列研究中，从试验注册处检索到合格的随机临床试验，并在文献数据库中进行检索以确定其发表状态。合格的随机临床试验为 2008 年 1 月 1 日至 2014 年 12 月 31 日期间的药物干预试验。搜索和分析于 2019 年 3 月 1 日至 8 月 31 日进行。试验注册处是世界卫生组织认可的主要注册处，或由中国食品药品监督管理局赞助的药物临床试验注册平台。
阳性和阴性结果的个体随机临床试验。
期刊文章分为主要文章（根据所有源自该随机临床试验的期刊文章中最大的样本量和最长的随访时间确定）和重复文章。重复文章分为 4 种类型：（1）未引用的亚组分析（文章本身并未披露为亚组分析或引用主要文章）；（2）未引用的再版（文章本身并未披露为主要文章的复制品或引用它）；（3）未引用的中期分析（文章本身并未披露为中期分析或引用主要文章）；（4）部分重复（文章本身并未披露其与其他文章共享部分参与者或引用它们）。
截至 2019 年 8 月，作为期刊文章发表的 470 项随机临床试验中，有 55 项（11.7%）有 75 篇重复文章，其中 53 篇（70.7%）为跨语言重复文章。在 75 篇重复文章中，33 篇（44.0%）为未引用的再版，25 篇（33.3%）为未引用的亚组分析，15 篇（20.0%）为未引用的中期分析，2 篇（2.7%）为部分重复。当随机临床试验的主要文章以中文发表时，阳性结果的后续重复发表的可能性是阴性结果的 2.48 倍（95%CI，1.08-5.71）。
在这项研究中，大多数重复文章是跨语言重复文章，最常见的类型是未引用的主要文章再版。当随机临床试验的主要文章以中文发表时，存在重复发表偏倚，可能会误导读者，并损害期刊和证据综合。
