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This section focuses on the full-text Cochrane
reviews that appear in the Cochrane Database of Systematic Reviews.
In the example below we look at the review of nicotine replacement therapy.
This describes the main features of a Cochrane review and highlights the
sections most likely to be relevant to users of the Library.
From the Search Results screen, you can view the full-text of articles by selecting Record for the item you are interested in.
Cochrane reviews can be very long, but they all follow a standard structure. When you select a Cochrane review to look at, the document display format includes a left-hand column table of contents that allows you to navigate within the review.
For a quick overview of the review’s findings, the following three
sections summarise the evidence:
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The Abstract
summarises the objectives, methods, results and conclusions.
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The Plain language summary
summarise the review in a straightforward style that can be understood
by consumers of health care.
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Authors’ Conclusions gives an overview
of the most important findings and discusses the implications for
practice and research.
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Nicotine replacement therapies (NRT), such as chewing gum and transdermal
patches, are widely promoted as helping people to resist the urge to smoke
by reducing the withdrawal symptoms associated with smoking cessation. Is
there any evidence to support this?
The Cochrane review Nicotine replacement therapy for smoking cessation
addresses this question. Using a comprehensive register of controlled trials
of smoking cessation, the review authors located 132 randomised trials that
compared different types of NRTs against a control (either a placebo or
no treatment). Because the review authors want to determine the long-term
effectiveness of NRT, they only included studies that reported smoking cessation
rates a minimum of six months after starting NRT.
More information about the types of studies, participants, interventions
and outcomes included in the review can be found in the Criteria for
considering studies for this review section.
The authors give detailed descriptions of the studies included in the review
and assess the quality of each study. It’s important that authors take
account of any concerns about the quality of the included studies when interpreting
the results. This is especially the case for reviews with small numbers
of studies. The reason for this is that we know poorer quality or less rigorously
conducted studies are likely to overestimate the benefits of the treatment
or intervention being tested.
More information about the studies included in the review can be found
in the Description of studies and Methodological quality sections.
The results of reviews are often summarised statistically (called meta-analysis)
as well as descriptively. In the review of nicotine replacement therapy
the results are based on evidence from over 130 randomised trials involving
over 40,000 smokers. The results found evidence that all forms of NRT made
it more likely that a person's attempt to quit smoking would succeed. The
chances of stopping smoking were increased by 50 to 70%.
More information can be found in the Results and Analyses
sections.
An overview of the most important findings is given in the form of Implications
for practice and Implications for research. Here the review's
authors confirm that nicotine replacement therapies increase long-term quit
rates. Other conclusions provide information on which smokers are likely
to benefit most, which doses are most effective, whether one form of NRT
is better than another, and the risk of adverse events. The Discussion
section will often include comments on any methodological limitations with
the review and set the results in the context of existing evidence and current
practice.
More information can be found in the Discussion and Authors’
conclusions sections.
Keeping reviews up-to-date is an important part of the review process. Unlike
articles that are published in paper journals, the electronic format of
Cochrane reviews allows new evidence to be incorporated as further trials
are published or identified. The review of nicotine replacement therapy,
for example, was first published in 1996. Since that time an additional
70 randomised trials have been published and included in the Cochrane review.
Finally, a unique feature of Cochrane reviews is the Submit Feedback facility.
Because the reviews are published electronically and are updated regularly,
readers of the review can submit comments that are then fed back to the
authors. The original comment(s) together with the response of the author(s)
will then appear on subsequent updates of the review. (Reviews that contain
comments submitted by readers are flagged with a Comment tag.) It is hoped
that enabling readers to contribute to the review process in this way will
lead to improvements in the quality and relevance of reviews in the Cochrane
Library.
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Printing Reviews
Because of the length of reviews (many are over 30 to 40 pages) think twice before hitting the print button! If you want to print the whole review, or particular sections, then we advise viewing the PDF version which you can link to from the top of the left-hand column.
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