Cochrane Reviews

What are Cochrane Reviews?

Cochrane Reviews are systematic reviews of primary research in human health care and health policy. They investigate the effects of interventions for prevention, treatment and rehabilitation. They also assess the accuracy of a diagnostic test for a given condition in a specific patient group and setting.

Each systematic review addresses a clearly formulated question; for example: Can antibiotics help in alleviating the symptoms of a sore throat? All the existing primary research on a topic that meets certain criteria is searched for and collated, and then assessed using stringent guidelines, to establish whether or not there is conclusive evidence about a specific treatment. The reviews are updated regularly, ensuring that treatment decisions can be based on the most up-to-date and reliable evidence.

“We care that you care enough to help us provide people all over the world, with a personal or professional interest in health care, with reliable information.”

- Sonja Henderson, Managing Editor of the Cochrane Pregnancy and Childbirth Group, Liverpool, UK

Cochrane Reviews are designed to facilitate the choices that practitioners, consumers, policy-makers and others face in health care. No other organisation matches the volume, scope and range of healthcare topics addressed by Cochrane Reviews.

As well as covering hundreds of medical conditions and diverse healthcare topics such as injury prevention and natural treatments, Cochrane Reviews have an international appeal through their global coverage of healthcare issues affecting people in all countries and contexts, including resource-poor settings, where it is vital to ensure that funds are used to maximum benefit.

Without Cochrane Reviews, people making decisions are unlikely to be able to access and make full use of existing healthcare research.

“To ensure that the work of The Cochrane Collaboration is relevant to low and middle-income countries it is essential that people from those countries actively participate.”

- Jimmy Volmink, Director of the South African Cochrane Centre and Coordinor of the Cochrane Developing Countries Network, Tygerberg, South Africa

Why are Cochrane Reviews different?

Cochrane Reviews are internationally recognised as the highest standard in evidence-based health care. Narrative reviews of healthcare research have existed for many decades, but are often not systematic. They may have been written by a recognised expert, but no one individual has the time to try to identify and bring together all relevant studies. Of more concern, an individual or company might actively seek to discuss and combine only the research which supports their opinions, prejudices or commercial interests. In contrast, a Cochrane Review circumvents this by using a predefined, rigorous and explicit methodology.

A Cochrane Review is a scientific investigation in itself, with a pre-planned Methods section and an assembly of original studies (predominantly randomised controlled trials (RCTs), but also sometimes, non-randomised observational studies) as their ‘subjects’. The results of these multiple primary investigations are synthesized by using strategies that limit bias and random error. These strategies include a comprehensive search of all potentially relevant studies and the use of explicit, reproducible criteria in the selection of studies for review. Primary research designs and study characteristics are appraised, data are synthesized, and results are interpreted.

“The Cochrane Collaboration has consistently involved consumers in its editorial processes, in the firm belief that the more consumers are involved, the more health services and research will grow in democracy, and will be tailored to people’s needs.”

- Silvana Simi, Consumer Coordinator for the Cochrane Multiple Sclerosis Group, Pisa, Italy

What is The Cochrane Library?

Cochrane Reviews are published in The Cochrane Library  ­– an online collection of databases that brings together in one place rigorous and up-to-date research on the effectiveness of healthcare treatments and interventions, as well as methodology and diagnostic tests.

There are over 4,000 Cochrane Reviews currently available in The Cochrane Library. As many as 2,000 protocols for Cochrane Reviews are also available, providing an explicit description of the research methods and objectives for Cochrane Reviews in progress.

The 2009 'Impact Factor' - a tool for ranking, evaluating and comparing journals - for the Cochrane Database of Systematic Reviews (the CDSR), a database of The Cochrane Library, has recently been judged to have been 5.653. This places the CDSR 11th out of the 132 journals included in the ISI Medicine, General and Internal journal list. Read more about Impact Factor here.

Hundreds of newly completed Cochrane Reviews and protocols are added to The Cochrane Library every year. In addition, existing Cochrane Reviews are updated regularly as new information becomes available. This is particularly important in the rapidly changing healthcare environment.

When considering usage across all web platforms (including Wiley InterScience, Cochrane.org, La Bibliotheca Cochrane Plus, Bireme, OVID and EBSCO), it is estimated that in 2009, there was a search on The Cochrane Library every 1 second, an abstract viewed every 2 seconds and a full text review downloaded every 3 seconds in 2009. See more usage data here.

Access The Cochrane Library here.

The future

The Cochrane Collaboration is striving to ensure that its work is sustainable. Even with thousands of Cochrane Reviews either published or under way, there is still a large amount of work to be done.

The latest estimate is that at least 10,000 Cochrane Reviews are needed to cover all healthcare interventions that have already been investigated in controlled trials, and these reviews will need to be updated at the rate of 5000 per year.

If the growth in The Cochrane Collaboration continues at the pace of the last few years, this target will be reached within the next decade or so. However, this will require continuing and evolving partnership and collaboration. The Cochrane Collaboration will need to continue to attract and support the wide variety of people who contribute to its work.

“Just as that idealistic organization - the United Nations - views every citizen of the world as a member - I view each person as a member of an equally idealistic organization: The Cochrane Collaboration.”

- Robert Dellavalle, Review author and editor for the Cochrane Skin Group, Colorado, USA

It will also need to work together with funders and providers of health care to ensure growth in the resources needed for the work, and accessibility of the output of the work to people throughout the world making decisions about health care.

Find out how you can become a contributor to The Cochrane Collaboration here.