Introduction
Since 1996, systematic
reviews prepared and maintained by the Cochrane Collaboration
have been published in The Cochrane Library, along with bibliographic
and quality-assessed material on the effects of healthcare interventions
submitted by others. Cochrane reviews have been published in one of
the components of The Cochrane Library, The Cochrane Database
of Systematic Reviews. These reviews are regularly updated as more
information becomes available and in response to comments and criticism.
They are now widely regarded as being of better quality, on average,
than their counterparts in print journals (Jadad et al. 1998).
The development of the Cochrane Collaboration has been described elsewhere
(Chalmers 1993; Chalmers and Haynes 1994; Bero
and Rennie 1995; Chalmers et al. 1997;
Dickersin and Manheimer 1998; Chalmers 2003), but the evolution of The Cochrane
Library has not previously been documented. As many of the systematic
reviews now appearing in The Cochrane Database of Systematic Reviews
were first published electronically in 1988, this seems likely to be
the longest running electronic publication in the field of health care.
Here we look at the evolution of The Cochrane Library as an electronic
publication between 1988 and 2003, and some of the features that set
it apart from more traditional publications.
A
letter to the Lancet, 1986
By the mid 1980’s, people had begun to recognise that it was impossible
to interpret the results of any one study in isolation, and that critical
summaries were needed to put the results into context. Indeed, it began
to be realised that, because a systematic approach to assessing research
on the effects of healthcare interventions was not being used, patients
were suffering and dying unnecessarily. These preventable tragedies
were illustrated dramatically in a comparison of advice in textbooks
and the information that could have been available had a scientifically
defensible approach been used to cumulate evidence as it emerged (Antman
et al. 1992).
 In
1979 Archie Cochrane had issued a call to assemble “a critical summary,
adapted periodically, of all … relevant randomized controlled trials”
(Cochrane 1979), and one of the fields in
which people had begun to heed this call by the mid-1980s was perinatal
medicine. Work had begun on developing registers of controlled trials
of interventions during pregnancy labour and early infancy (Grant
and Chalmers 1981; Chalmers et al.
1986), and the advantages of a more systematic approach to reviewing
evidence about the effects of healthcare interventions, sometimes combining
data from similar studies to create an overall estimate of effect, had
also been demonstrated, both in ‘stand alone’ reviews (Chalmers
1979), and in setting the results of new studies in context (Saunders et al. 1985). The stage was set at the
National Perinatal Epidemiology Unit in Oxford to coordinate the creation
of a body of systematic reviews in pregnancy and childbirth.
Advances in computer technology were making it possible to consider
more ambitious projects. LexisNexis had shown the legal
profession the advantages of bringing together reference literature
in a database format, and electronic publication held the promise of
new ways of assembling and delivering information.
With the earlier example from the perinatal field in mind (Saunders
et al. 1985), a letter to the Lancet published in August 1986 (Chalmers 1986) applauded the editor’s decision to
include a “lengthy tailpiece” putting in context the results of the very
large ISIS-1 trial (ISIS-1 Collaborative group 1986),
which had been preceded by many other trials addressing the same question.
The letter acknowledged that this was difficult to do in a print journal
because of lack of space, and noted the advantages that electronic publication
had to offer. Space is limited in printed journals, consequently the amount
of detail that can be included in the background and methods sections,
as well as in the presentation of results, is restricted. Recognition
that the electronic world was not limited in this way allowed people to
consider new approaches to presenting and summarising of research evidence.
One such approach, heralded in the letter to the Lancet, was The Oxford
Database of Perinatal Trials.
The first electronic publication to present regularly updated systematic
reviews of research on the effects of healthcare interventions was The
Oxford Database of Perinatal Trials (Chalmers 1988) - known to many
affectionately as “Odd Pot” (ODPT).
ODPT was funded by Oxford University Press as part of an ambitious
project at the UK’s National Perinatal Epidemiology Unit to systematically
review the effects of care in pregnancy and childbirth. Drawing on the
experience and success of the Classified Bibliography of Controlled
Trials in Perinatal Medicine (National Perinatal Epidemiology
Unit 1985), ODPT initially sought to provide registers
of perinatal trials to “provide a resource for reviews of the safety
and efficacy of interventions used in perinatal care…” (Chalmers et al. 1986).
A computerised register of randomised controlled trials in perinatal
medicine had been designed and developed earlier (Mugford
et al. 1982). ODPT went beyond storing bibliographic information
on the clinical trials that formed the material for systematic reviews.
In an innovative step, ODPT was expanded to include:
- raw data from the clinical trials, i.e., the results of the trials,
and
- commentaries on the analyses, i.e., the full text of the systematic
reviews themselves.
In addition, ODPT was conceptualised as a publication in its
own right. The database became one of a trio of complementary products
to emerge from the National Perinatal Epidemiology Unit and published
by Oxford University Press. These products, all based on the trial registers
and systematic reviews, included in addition to ODPT, the 2-volume
reference work Effective Care in Pregnancy and Childbirth (Chalmers
et al. 1989), and a paperback, reader-friendly version stripped
of statistics and references, A Guide to Effective Care in Pregnancy
and Childbirth (Enkin et al. 1989). This was a powerful
collection, of direct relevance to practitioners, pregnant women and
their families, researchers, policy makers and others interested in
pregnancy and childbirth.
ODPT was a valuable addition to the printed work. Published
twice yearly, first on 5¼ inch and then on 3½ inch diskettes, it had
several advantages as an electronic publication, not the least of which
was that the systematic reviews could be maintained and updated after
the books had gone to print. Distribution of ODPT on a subscription
basis also provided the opportunity to circulate newsletters highlighting
new or substantially revised reviews (see Spring Newsletter 1992).
ODPT was developed using a popular microcomputer database program
based on the “dBase” file specification. The reviews were not held as
documents per se. Instead, a relational database was used, and
the data were stored in a highly structured form. All references, for
example, were held in one file, while all author’s names and affiliations
were held in another. Similarly, the titles of all comparisons in the
analyses were held together, as were the data extracted from each of
the included studies. As a consequence, the systematic reviews themselves
were highly structured, and were all in the same format.
The systematic reviews in ODPT were known as “overviews” to
distinguish them from the ongoing, planned, unpublished and published
trial reports that were also included in the database. As the term
suggests, overviews were summaries of groups of studies evaluating similar
interventions. Each overview had a designated ‘editor’, who provided
a structured textual summary termed the ‘Editorial Commentary’.
The overviews in ODPT were data orientated. Data on different
outcomes following the interventions studied were considered ‘Parts’
of the overview, and within each Part, where possible and appropriate,
the software would display the data from each included study and produce
a statistical summary or meta-analysis. The analyses were based on the
notion of calculating odds ratios from the outcome data of the individual
trials, and then pooling the odds ratios to get an overall estimate
of effect (cf. Saunders et al. 1985).
This highly structured approach to presentation gave the reader an
important advantage: once you understood how to read one graph and how
to interpret a couple of statistics, you could apply that understanding
to all reviews in the database. This removed one of the big barriers
between research and practice, namely the effort required to figure
out how the researchers had analysed the data and had reached their
conclusions. The process was transparent and consistent for the reviews
presented in ODPT.
Unlike more traditional printed articles, the ODPT database
system allowed the raw data used in the meta-analyses to be stored with
the article, which in turn meant that statistics could be calculated
and figures drawn in ‘real time’, that is, when the figure was displayed.
As new studies were added to the database, and new data became available,
they were automatically incorporated in the analyses.
One interesting feature when displaying meta-analyses in ODPT
was that you could watch the pooled effect estimate and confidence interval
change as each trial was added into the analysis, the ordering being
based on the assessed quality of each study, its statistical power,
or its year of publication.
Storing the data with the reviews also meant that when it came time
to produce the graphs for the 2-volume book Effective Care in Pregnancy
and Childbirth (Chalmers et al. 1989), a software program could
be written to step through the database and produce the graphs and figures
for delivery to the publisher. The data published in printed form represented
a ‘time-slice’ or ‘snap-shot’ of the state of research evidence at the
time of submission for publication.
By 1992, many policy makers, practitioners, and consumers had come to
recognise the importance of systematic reviews for making decisions
about health care. The books Effective Care in Pregnancy
and Childbirth (Chalmers et al. 1989)
and Effective Care of the Newborn Infant (Sinclair & Bracken 1992) were acknowledged
as important achievements within the profession, and A Guide to Effective
Care in Pregnancy and Childbirth (Enkin
et al. 1989) in paperback had proved popular with professionals
and non-professionals alike.
The Oxford Database of Perinatal Trials (Chalmers
1992) was being maintained at the National Perinatal Epidemiology
Unit, and an international team of contributors was updating the systematic
reviews. As the editors of ODPT recounted at the time:
“If we had the opportunity to begin again from
the beginning, we might well have decided that, before any attempt was
made to prepare either of the books, all of the systematic reviews on
which they were based should have been completed, with structured reports
prepared, and held in electronic form.” (Millbank Quarterly Special
Issue 1993).
Although the books had proved popular, Oxford University Press found
the electronic publication costly to maintain, and in the end concluded
that it was not economically viable. In 1992, Oxford University Press
decided to discontinue ODPT as a commercial product.
While it was hoped that central funding could be obtained to support
the dissemination of the database, this was not to be the case. In the
United Kingdom, supporting the production of systematic reviews was
recognised as a legitimate use of research and development money, but
the dissemination of systematic reviews was not. In addition, plans
were being made to create a national Centre for Reviews and Dissemination,
but the exact remit of the Centre was undecided. These two factors contributed
to the decision by the National Health Service Research and Development
Programme not to fund dissemination, and so commercial models were again
pursued.
It was still early days in the history of electronic publishing. The
World Wide Web had yet to gain popularity, and attempts to interest
other publishers in taking over the publication of ODPT were
not successful. The most likely successor to ODPT at the time
was an ambitious project known as ‘Medical Knowledge’, which was to
be a publication under the auspices of the newly formed Maxwell Electronic
Publishing. This project ended following Robert Maxwell’s death in 1991
(http://news.bbc.co.uk/1/hi/business/1249739.stm).
Personal computer technology was changing quickly in the early 1990s,
and access to desktop computers was becoming commonplace. In 1992, Update
Software redesigned ODPT in an attempt to bring the systematic
reviews to the forefront, and to make the information more accessible
to the average computer user. The result was that in April 1993, Update
Software reissued the systematic reviews contained in The Oxford
Database of Perinatal Trials as an electronic publication entitled
The Cochrane Pregnancy
and Childbirth Database (CCPC).
At the same time, the then recently established Research and Development
Programme of the UK National Health Service had recognised the value
of the work being done at the National Perinatal Epidemiology Unit and
provided funds for a new centre, the UK Cochrane Centre, to promote
an extension of the process to other areas of healthcare. The development
and launch of CCPC thus coincided with the opening of the UK
Cochrane Centre in October 1992, and planning for the launch of the
international Cochrane Collaboration in October 1993. CCPC was
designed in part as a pilot to show how Cochrane Reviews in all areas
of healthcare could be published electronically. The original title
of the publication was the “Cochrane Collaboration Pregnancy and Childbirth
database”, hence the double ‘C’s in CCPC.
The reviews in CCPC were organised under topics following the
natural progression of pregnancy and childbirth, from “Care during pregnancy”
to “Unhappiness after childbirth”. Each review included a summary graph
displaying the pooled effect measure for each outcome included in the
review. This meant the there was a single figure, generated directly
from the stored data, which summarised the review. The software allowed
the user to start at the beginning of the database, and, using the PageDown
key on the computer keyboard, display each summary graph in turn until
the end of the database was reached. By 1994, Issue 2, there were 615
reviews included in CCPC.
The highly structured nature of the reviews in CCPC allowed
for very specific search and retrieval facilities. It was possible,
for example, to search on the entry characteristics for the studies
reviewed (for example, women who had had Caesarean sections), the intervention
reviewed (for example, Caesarean section), and/or the outcome measured
(for example, number of women having Caesarean sections after induction
of labour).
When the second edition (Enkin et al. 1995) of A Guide to Effective
Care in Pregnancy and Childbirth (GECPC) was commissioned,
the editors were able to start at the top of the topic list and step
through the database summarising the evidence available under each topic.
One immediate benefit of the relationship between the database and the
book was that it allowed linking the individual reviews to text from
the relevant chapters. That is, while reading a review on screen, a
single keystroke allowed the reader to display the relevant chapter
of the book. For example, the review “Upright versus recumbent position
during the second stage of labour” was linked to the GECPC Chapter
2, ‘The Second Stage of Labour’, which includes a discussion of position
during labour.
CCPC proved very popular and sold over 1000 copies in the first
year, which was remarkable given that it was still early days in electronic
publishing. It was especially popular among midwives and others who
did not have ready access to the research literature. Including the
text from GECPC in the electronic publication was a significant
contribution, in part because it provided those not familiar with the
research literature with a context in which it could be interpreted.
The Cochrane Collaboration was inaugurated in October 1993, but it continued
to be difficult to interest publishers in an exclusively electronic
publication. The most promising discussions were with the American Association
for the Advancement of Science (AAAS), which had just launched an electronic
journal named the Online Journal of Current Clinical Trials (hosted
by OCLC – Online Computer Library Center, Inc; click
here for a description of the Online Journal). The idea was to create
a separate section for Cochrane Reviews in the Online Journal of
Current Clinical Trials. It was proposed that authors prepare the
documents electronically, and, once approved by the appropriate Cochrane
Review Group, the reviews would be sent electronically and automatically
published on the OCLC system. These discussions ultimately failed to
progress, in part because of the legal implications of AAAS and OCLC
publishing ‘sight unseen’ material from international sources over which
they had no editorial control.
Update Software continued to develop a system for managing and disseminating
registers of trials and systematic reviews, and by October 1994, at
the 2nd Cochrane Colloquium in Hamilton, Ontario, Canada,
Update Software demonstrated a prototype of a new CD-ROM publication,
The Cochrane Database of Systematic Reviews (CDSR).
The Cochrane Collaboration was, and continues to be, a loose-knit organisation.
It is based on the enthusiasm of people wishing to contribute and does
not have an easily defined membership. The CD-ROM publication provided
a means of communication among those interested in the work of the Collaboration,
as well as an outlet for the work of the Collaboration. The CD-ROM listed
contact details of all groups in the Collaboration, including the reference
Cochrane Centres for all countries in the world. It also included listings
of titles of planned reviews, and protocols for reviews in preparation.
CDSR continued the tradition established with CCPC, where
authors retained copyright and were encouraged to publish articles in
print journals based on the reviews held in electronic form. In keeping
with the spirit of Collaboration, and as an incentive to publish, each
author was given a complimentary subscription to the CD-ROM publication.
The original information management system supporting the Oxford Database
of Perinatal Trials was a program named the Oxford Database Manager
(ODMAN). This started the ‘manager’ naming convention that has
persisted to this day. ODMAN was maintained at the National Perinatal
Epidemiology Unit in Oxford, UK, and all data were entered and reviews
created on this one system.
With the development of the Cochrane Collaboration, it became clear
that the resources were not available for a centralised management system.
“Let a hundred flowers bloom” was the sentiment of the time. The Cochrane
Collaboration was committed to building on the enthusiasm of individuals.
In response to this new organisation, Update Software introduced a review
authoring tool, the Review Manager (RevMan), that was intended
to allow individuals to produce the highly structured reviews that featured
in ODPT and CCPC. The information management system was
designed to mirror the structure of the Collaboration, where systematic
reviews produced by individual authors were authored in RevMan,
and then sent to the editorial bases of Collaborative Review Groups
where they were assembled into modules of reviews using a Module
Management program (ModMan). The modules were then sent to
Update Software where they were assembled to form a Parent Database
from which publications could be derived.
This system has remained intact for 10 years now and the software programs
supporting the system remain virtually unchanged. RevMan was
first released in July 1993 (RevMan 1.03 for DOS) followed by versions
2 and 3 in November 1995 and October 1996, respectively. Interim versions
have been released subsequently but it was recognised that a period
of stability was desirable and so no major changes were made for a couple
of years. At present, RevMan 4.2 is available without charge
on the Internet at http://www.cochrane.de/cochrane/revman.htm.
In 1997, Update Software gave the Information Management System to
the Collaboration, and the Nordic Cochrane Centre took over responsibility
for maintaining RevMan. A few years later, in 2001, the Nordic
Cochrane Centre assumed responsibility for developing ModMan
as well. The RevMan software has always been freely available
and has been used widely to produce systematic reviews outside the Cochrane
Collaboration.
The great advantage of using the authoring tool was that all documents
had the same structure and the different parts of the document could
be readily identified and independently manipulated. This allowed them
to be transformed into different formats for different publishing systems.
Over the years, Cochrane Reviews have appeared as ASCII text, in MARC
formats (www.loc.gov/marc),
using Standardized General Markup Language (SGML), HyperText Markup
Language (HTML), and Extensible Markup Language (XML; see http://www.w3.org
for information on standard technologies for Web publishing), as well
as proprietary formats for specialised products.
The
Cochrane Library
It was clear from the start of the Cochrane Collaboration in 1993 that
it would be many years before the majority of reliable research studies
assessing the effects of healthcare interventions could be placed in
the context of a systematic review. It was also clear that the Cochrane
Collaboration was not the only group producing high-quality reviews.
In addition, while the management software supporting The Cochrane
Database of Systematic Reviews helped to create structured reviews
in many different clinical areas, it was missing one essential element:
the register of trials that provided the source material for the systematic
reviews.
In 1995, Update Software convened an advisory group that recommended
creating a library of information sources to inform decision-making
in healthcare and to help in the production of systematic reviews. David
Sackett, then Chair of the Cochrane Collaboration, welcomed the suggestion
and authorised its implementation by Update Software. Thus it was that,
in April 1996, Update Software presented the first issue of The Cochrane
Library. This incorporated:
- Regularly-updated systematic reviews and protocols for reviews in
preparation, in the Cochrane Database of Systematic Reviews
(contributed by the Cochrane Collaboration)
- Quality appraisals of reviews published elsewhere, in the Database
of Abstracts of Reviews of Effectiveness (contributed by the UK
National Health Service Centre for Reviews and Dissemination)
- A register of controlled trials, in the Cochrane Controlled Trials
Register (assembled by Update Software from registers submitted
by Cochrane Centres and Cochrane review groups, together with entries
downloaded from MEDLINE and Embase)
- A register of articles on the science of reviewing evidence (contributed
by the Oslo branch of the Nordic Cochrane Centre)
- Information about the Cochrane Collaboration (assembled from material
supplied by the Cochrane Collaboration)
The first three of these collections were viewed as part of a hierarchy
of evidence, ranging from regularly updated reviews, to high-quality
reviews published elsewhere, to reports of individual controlled trials.
The intention was to extend this range to include planned and ongoing
trials (cf. Chalmers et al. 1986)
and topic summaries such as those from the Guide to Effective Care
in Pregnancy and Childbirth (cf. CCPC).
The Cochrane Library was accessed using specially written software
that allowed rapid searching of all documents in the collection, while
distinguishing between types of documents when reporting the results
of the search. That is, after entering search criteria, the user was
shown the number of regularly updated systematic reviews that met the
criteria, followed by the number of reviews published elsewhere, then
the number of trial reports, and so forth. This design was intended
to emphasise the differences between the types of documents retrieved
by a search strategy, a design now known as a “thematic approach to
information retrieval” and was unusual at the time.
MetaView
The Cochrane Library used a novel approach to presenting figures
and graphs, and further developed the strategy of separating the data
themselves from displays of the data. In most scientific publications,
figures and graphs are stored as images. The Cochrane Library
broke with this tradition and continued the strategy first used in ODPT
- storing raw data with the Cochrane Reviews and generating figures
and graphs in ‘real time’, that is, at the time when they were displayed.
In the case of The Cochrane Library, this was accomplished by
developing a specialised program named MetaView that acted as a “data
viewer”. MetaView was included with the authoring tool RevMan to allow
the review authors to calculate statistics and view figures and graphs.
MetaView was also included with the CD-ROM and later Internet versions
of The Cochrane Library, which meant not only that readers of
reviews could view the same figures and graphs as the authors, but they
could select different statistics and manipulate the data as well.
Technically, this was a very efficient method of publishing figures
and graphs. By 2003 there were almost 35,000 graphs with over 100,000
trial outcomes with numerical data to be displayed. The numerical data
needed to create a graph could be transmitted far more rapidly than
the graph images themselves, and the space saved by storing numerical
data allowed the database to be published on CD-ROM.
This approach was criticized by some statisticians (Senn 2000), who argued that the average reader would
not know what statistics were appropriate to a given data set (e.g.,
odds ratio or relative risk; fixed effect or random effect analysis),
and in recent years reviewers have had the option of setting a default
analysis.
Comments
and criticisms
Each completed review and review protocol appearing in The Cochrane
Library includes contact details for both the reviewer(s) and
the Collaborative Review Group responsible for the review. Readers were
encouraged from the outset to use these contacts if they had criticisms
or suggestions for how the review might be improved. Comments on review
protocols provide a form of ‘pre-publication’ feedback on how the reviewers
plan to conduct the review. Comments made ‘post-publication’ provide
a mechanism for ongoing feedback on such topics as the methods used,
the questions addressed, and the conclusions reached. Reviewers and
review group editors take these comments into account when updating
the reviews. By updating reviews in response to comments and criticisms,
mistakes can be corrected and the overall quality of the review will
continue to improve.
Update Software launched a formal ‘Comments and Criticisms’ system
for Cochrane Reviews at the 4th Cochrane Colloquium in Adelaide, Australia,
in 1996. In its current form, the system allows readers to post comments
to a Web site from links in the reviews, the abstracts of reviews, or
directly (see links in the review abstracts at www.update-software.com/cochrane/abstract.htm).
Once posted, a copy of the comment is automatically forwarded to the
Collaborative Review Group responsible for the review and to a Criticism
Editor, who in turn passes the comment or a summary of the comment to
the appropriate reviewer. When the review is updated, either the comment
or the Criticism Editor’s summary of the comment along with the reviewer’s
reply is published as part of the updated review. Reviewers, editors
and others may also reply to the comment directly on the Web site.
Update Software distributed The Cochrane Library from January
1997 to March 2003. The dissemination strategy, as agreed with the Cochrane
Collaboration, was to make The Cochrane Library available directly
to subscribers, and to prepare the reviews and other resources for those
wishing to disseminate the material on other platforms.
In September 1996, for example, The Cochrane Database of Systematic
Reviews was made available on the World Wide Web in partnership
with Synapse Publishing Inc. Update Software worked with Ovid Technologies
to prepare data for use in Evidence Base Medicine Reviews, launched
in October 1998.
Similarly, the World Health Organisation sponsored the WHO
Reproductive Health Library. This highly successful disk-based
product disseminated a selection of Cochrane reviews relevant to developing
countries, together with practitioners’ comments on the applicability
of the reviews in different practice settings. Evidence-based
medicine guidelines presented treatment recommendations backed
by evidence summaries and the full text of Cochrane Reviews. This allows
a ‘drill-down’ approach where readers can examine for themselves the
evidence on which treatment recommendations had been based.
By 2003, Cochrane Reviews were available from most major information
providers, including Dialog and DataStar, EBSCO, SilverPlatter and Ovid.
Open access over the Internet was provided in several countries, including
Australia, Finland, Ireland, Norway and the United Kingdom. The Cochrane
Library was also made available throughout Latin America and the
Caribbean through the BIREME
system, and to all low- and low-middle countries as defined by the World
Bank, through the HINARI,
INASP and TALC
programs.
Discussion
Evidence-based healthcare in general, and systematic reviews in particular,
have achieved widespread recognition in the years since ODPT was first
published 1988. In 2003, for example, the “Grady
Filters” on the Emory University Health Libraries Web site retrieved
over 8500 systematic reviews, including health-technology assessments,
when used on PubMed.
Although no longer unique, Cochrane reviews remain distinctive because
their electronic publication allows two key features difficult to achieve
with traditional print media:
(1) because there are no practical constraints on space, systematic
reviews published electronically can include more transparently details
of background, materials and methods, data presentation and analysis,
which would often have to be omitted in print documents.
(2) reviews published electronically can be updated as new information
becomes available and when mistakes or other ways of improving them
are identified. This makes it possible to produce a reference work that
is continually improving in content and quality.
Although there are a great number of electronic publications available
on CD-ROM and over the Internet today, most of these contain ‘papers’
originally intended for print journals. In general, the electronic
versions of the major medical journals have been judged to be very much
like their print counterparts, and in many respects have failed to live
up to expectations (Delamothe 2002).
The Cochrane Library differs from traditional publications in
that it was conceived as an electronic publication from the outset,
and was designed to take advantage of features unique to electronic
publishing. It illustrates how an electronic publication was developed
in its own right to improve the quality and relevance of published reports
of scientific information. Cochrane reviews are now widely cited in
policy documents and practice guidelines (Holmes et al. 2001). Hopefully they will also
be used increasingly to improve the quality of Discussion sections in
reports of new research on the effects of health care (Clarke
et al. 2002). In these ways, The Cochrane Library has helped
and should continue to help ensure that healthcare interventions do
more good than harm.
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