考克兰META分析研究的描述（横断面研究）

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今日，考克兰协作网官方网站发表了一篇研究成果。

由Jonathan Davey1, Rebecca M Turner1*, Mike J Clarke2 and Julian PT Higgins1研究对考克兰的META分析进行总体的横断面研究。该研究发表在【Davey et al. BMC Medical Research Methodology 2011, 11:160】

*                                                                         Corresponding author:                                                                                            Rebecca M Turner rebecca.turner@mrc-bsu.cam.ac.uk

[url=]Author Affiliations[/url]

1                                MRC Biostatistics Unit, Institute of Public Health, Cambridge, UK                           
2                                All-Ireland Hub for Trials Methodology Research, Centre for Public Health, Queen's University Belfast, Northern Ireland                           

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BMC Medical Research Methodology 2011, 11:160 doi:10.1186/1471-2288-11-160

The electronic version of this article is the complete one and can be found online at: http://www.biomedcentral.com/1471-2288/11/160

Received:	9 May 2011
Accepted:	24 November 2011
Published:	24 November 2011

© 2011 Davey et al; licensee BioMed Central Ltd.

                                This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.                       

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Abstract
Background: Cochrane systematic reviews collate and summarise studies of the effects of healthcare interventions.
The characteristics of these reviews and the meta-analyses and individual studies they contain provide insights into
the nature of healthcare research and important context for the development of relevant statistical and other
methods.
Methods: We classified every meta-analysis with at least two studies in every review in the January 2008 issue of
the Cochrane Database of Systematic Reviews (CDSR) according to the medical specialty, the types of interventions
being compared and the type of outcome. We provide descriptive statistics for numbers of meta-analyses,
numbers of component studies and sample sizes of component studies, broken down by these categories.
Results: We included 2321 reviews containing 22,453 meta-analyses, which themselves consist of data from
112,600 individual studies (which may appear in more than one meta-analysis). Meta-analyses in the areas of
gynaecology, pregnancy and childbirth (21%), mental health (13%) and respiratory diseases (13%) are well
represented in the CDSR. Most meta-analyses address drugs, either with a control or placebo group (37%) or in a
comparison with another drug (25%). The median number of meta-analyses per review is six (inter-quartile range 3
to 12). The median number of studies included in the meta-analyses with at least two studies is three (interquartile
range 2 to 6). Sample sizes of individual studies range from 2 to 1,242,071, with a median of 91
participants.
Discussion: It is clear that the numbers of studies eligible for meta-analyses are typically very small for all medical
areas, outcomes and interventions covered by Cochrane reviews. This highlights the particular importance of
suitable methods for the meta-analysis of small data sets. There was little variation in number of studies per metaanalysis
across medical areas, across outcome data types or across types of interventions being compared.

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蓝鱼版主真是敬业啊，除夕之夜还在SIFIC论坛上耕耘！辛苦了！