Cochrane library page also gives you info on what is Cochrane library
and how to access it. But here is a simple explanation.
Cochrane reviews investigate the effects of interventions for
prevention, treatment and rehabilitation in a healthcare setting. They
are designed to facilitate the choices that doctors, patients, policy
makers, and others face in health care.
Most Cochrane reviews are
based on randomised controlled trials, but other types of evidence may
also be taken into account, if appropriate. Cochrane reviews have the
following general features:
w A structured
format helps the reader to find his/her way around the review
easily.
w A detailed methods
section allows the reader to assess whether the review was
done in such a way as to justify its conclusions.
w The quality
of clinical studies to be incorporated into a review is carefully
considered, using predefined criteria.
w A thorough and
systematic search strategy, which includes searches for
unpublished and non-English records, aims to provide as complete a
picture as possible to try to answer the question considered.
w If the data collected in a review are of
sufficient quality and similar enough, they are summarised statistically
in a meta-analysis, which generally
provides a better overall estimate of a clinical effect than the results
from individual studies. A meta-analysis also allows the reviewer to
explore the effect of specific characteristics of given studies (for
example, study quality) on the reported results (for example, does
exclusion of non-randomised studies change the overall result?). It also
allows an exploration of the effects of an intervention on sub-groups of
patients (for example, does the treatment have a different effect on
smokers compared with non-smokers?).
w Reviews aim to be relatively easy
to understand for non-experts (although a certain amount of
technical detail is always necessary). To achieve this, Review Groups
like to work with "consumers", for example patients, who also
contribute by pointing out issues that are important for people
receiving certain interventions. Additionally, the Cochrane Library
contains glossaries to explain
technical terms.
w Multinational
editorial teams try to ensure that a review is applicable in different
parts of the world.
w Reviews are updateable.
Results from newly completed or identified clinical trials can be
incorporated into the review after publication. Additionally, readers
can send in comments and criticisms to
any review, and reviews may be changed accordingly to improve their
quality.
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Structure of a Cochrane
Review
This is the general layout of a Cochrane Review:
1. Synopsis - a short summary of the
review, specifically aimed at lay people
2. Structured Abstract - a
structured summary of the review, subdivided into similar sections as
the main review. This may be published independently from the review and
appears on the medical bibliographic database Medline.
3. Background - this gives an
introduction to the question considered, including, for example, details
on causes and incidence of a given problem, the possible mechanism of
action of a proposed treatment, uncertainties about management options
etc.
4. Objectives - short statement of
the aim of the review.
5. Selection criteria - brief
description of the main elements of the question under consideration.
This is subdivided into:
- Types of studies - for example,
randomised controlled trials.
- Types of participants - the
population of interest. This section may include details of
diagnostic criteria, if desired or appropriate.
- Types of interventions - the main
intervention under consideration and any comparison treatments.
- Types of outcome measures - any
outcome measures/endpoints (for example, reduction in symptoms) that
are considered important by the reviewer, defined in advance; not
only outcome measures actually used in trials.
6. Search strategy for identification of
studies - details of how an exhaustive identification of
relevant information was attempted, including details of searches of
electronic databases, searches for unpublished information,
handsearching of journals or conference proceedings, searching of
reference lists of relevant articles, etc.
7. Methods of the review -
description of how studies eligible for inclusion in the review were
selected, how their quality was assessed, how data were extracted from
the studies, how data were analysed, whether any subgroups were studied
or whether any sensitivity analyses were carried out, etc.
8. Description of studies - how many
studies were found, what were their inclusion criteria, how big were
they, etc.?
9. Methodological quality of included studies
- were there any reasons to doubt the conclusions of any studies because
of concerns about the study quality?
10. Results - what do the data show?
The results section may be accompanied by a graph to show a
meta-analysis, if this was carried out.
11. Discussion - interpretation and
assessment of results.
12. Reviewers' conclusions -
subdivided into Implications for practice
and Implications for research.
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A multi-stage process
Preparing and maintaining a Cochrane Review is a process with many
stages. In contrast to the practices of most print journals, reviewers
do in general not approach the Cochrane Editorial Base with their
finished review, but the Editorial Base provides an input to the review
process from the very beginning. Suggested review titles
are thoroughly discussed with the Editorial Team, reviewers are then
encouraged to attend a protocol workshop,
which leads to the preparation and subsequent publication of a protocol,
i.e. a plan of how the review will be carried out. This is followed by
work on the main review, with help available for problems with
statistical or methodological issues and with trials searching. The
Editorial Team will also try to help with any other issues. Finally, the
reviewers, with the help of the Editorial Team, are responsible for updating
their review regularly (usually about once a year). At all stages of the
process, the work is carefully checked by members of the Editorial Team
and by external referees to ensure its quality.
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