College of Social Work, University of Utah, Salt Lake City, Utah, United States of America.
PLoS One. 2012;7(5):e36626. doi: 10.1371/journal.pone.0036626. Epub 2012 May 4.
There is no specific guidance for the reporting of Cochrane systematic reviews that do not have studies eligible for inclusion. As a result, the reporting of these so-called "empty reviews" may vary across reviews. This research explores the incidence of empty systematic reviews in The Cochrane Database of Systematic Reviews (The CDSR) and describes their current characteristics.
METHODOLOGY/PRINCIPAL FINDINGS: Empty reviews within The CDSR as of 15 August 2010 were identified, extracted, and coded for analysis. Review group, original publication year, and time since last update, as well as number of studies listed as excluded, awaiting assessment, or on-going within empty reviews were examined. 376 (8.7%) active reviews in The CDSR reported no included studies. At the time of data collection, 45 (84.9%) of the Cochrane Collaboration's 53 Review Groups sustained at least one empty review, with the number of empty reviews for each of these 45 groups ranging from 1 to 35 (2.2-26.9%). Time since original publication of empty reviews ranged from 0 to 15 years with a mean of 4.2 years (SD = 3.4). Time since last assessed as up-to-date ranged from 0 to 12 years with a mean of 2.8 years (SD = 2.2). The number of excluded studies reported in these reviews ranged from 0 to 124, with an average of 9.6 per review (SD = 14.5). Eighty-eight (23.4%) empty reviews reported no excluded studies, studies awaiting assessment, or on-going studies.
There is a substantial number of empty reviews in The CDSR, and there is some variation in the reporting and updating of empty reviews across Cochrane Review Groups. This variation warrants further analysis, and may indicate a need to develop guidance for the reporting of empty systematic reviews in The CDSR.
对于没有符合纳入标准的研究的 Cochrane 系统评价，目前尚无特定的报告指南。因此，这些所谓的“空评论”在各评论中的报告方式可能存在差异。本研究旨在探讨《Cochrane 系统评价数据库》（The CDSR）中空系统评价的发生率，并描述其当前特征。
方法/主要发现：截至 2010 年 8 月 15 日，从《Cochrane 系统评价数据库》中确定、提取并编码分析了空评论。审查小组、原始出版年份以及上次更新以来的时间，以及在空评论中列出的排除、待评估或正在进行的研究数量都进行了检查。在《Cochrane 系统评价数据库》中，376 篇（8.7%）活跃的系统评价未报告纳入的研究。在数据收集时，Cochrane 协作组的 53 个审查小组中有 45 个（84.9%）至少维持了一篇空评论，这 45 个小组中的每一个的空评论数量从 1 到 35 不等（2.2-26.9%）。空评论的原始出版时间从 0 年到 15 年不等，平均为 4.2 年（SD=3.4）。上次评估为最新的时间从 0 年到 12 年不等，平均为 2.8 年（SD=2.2）。这些评论报告的排除研究数量从 0 到 124 不等，平均每篇评论 9.6 篇（SD=14.5）。88 篇（23.4%）空评论未报告排除研究、待评估研究或正在进行的研究。
《Cochrane 系统评价数据库》中有相当数量的空评论，而且各 Cochrane 评论小组在空评论的报告和更新方面存在一些差异。这种差异需要进一步分析，并且可能表明需要为《Cochrane 系统评价数据库》中空系统评价的报告制定指南。
