Montori Victor M, Wilczynski Nancy L, Morgan Douglas, Haynes R Brian
Division of Diabetes and Internal Medicine, Mayo Clinic, Rochester, Minnesota, USA.
BMC Med. 2003 Nov 24;1:2. doi: 10.1186/1741-7015-1-2.
Systematic reviews summarize all pertinent evidence on a defined health question. They help clinical scientists to direct their research and clinicians to keep updated. Our objective was to determine the extent to which systematic reviews are clustered in a large collection of clinical journals and whether review type (narrative or systematic) affects citation counts.
We used hand searches of 170 clinical journals in the fields of general internal medicine, primary medical care, nursing, and mental health to identify review articles (year 2000). We defined 'review' as any full text article that was bannered as a review, overview, or meta-analysis in the title or in a section heading, or that indicated in the text that the intention of the authors was to review or summarize the literature on a particular topic. We obtained citation counts for review articles in the five journals that published the most systematic reviews.
11% of the journals concentrated 80% of all systematic reviews. Impact factors were weakly correlated with the publication of systematic reviews (R2 = 0.075, P = 0.0035). There were more citations for systematic reviews (median 26.5, IQR 12 - 56.5) than for narrative reviews (8, 20, P <.0001 for the difference). Systematic reviews had twice as many citations as narrative reviews published in the same journal (95% confidence interval 1.5 - 2.7).
A few clinical journals published most systematic reviews. Authors cited systematic reviews more often than narrative reviews, an indirect endorsement of the 'hierarchy of evidence'.
系统评价总结了关于特定健康问题的所有相关证据。它们有助于临床科学家指导其研究，并帮助临床医生了解最新情况。我们的目的是确定系统评价在大量临床期刊中的集中程度，以及评价类型（叙述性或系统性）是否会影响引用次数。
我们通过手工检索普通内科、初级医疗保健、护理和心理健康领域的170种临床期刊来识别综述文章（2000年）。我们将“综述”定义为任何在标题或章节标题中标记为综述、概述或荟萃分析的全文文章，或者在正文中表明作者意图是对特定主题的文献进行综述或总结的文章。我们获取了发表系统评价最多的五种期刊中综述文章的引用次数。
11%的期刊集中了所有系统评价的80%。影响因子与系统评价的发表呈弱相关（R2 = 0.075，P = 0.0035）。系统评价的引用次数（中位数26.5，四分位数间距12 - 56.5）多于叙述性综述（8，20，差异P <.0001）。在同一期刊上发表的系统评价的引用次数是叙述性综述的两倍（95%置信区间1.5 - 2.7）。
少数临床期刊发表了大多数系统评价。作者引用系统评价的频率高于叙述性综述，这是对“证据等级”的间接认可。
