Understanding systematic reviews - Cochrane systematic reviews made simple


Systematic reviews are research. Cochrane systematic reviews are amongst the best quality systematic reviews. They are done by people linked to The Cochrane Collaboration and are all published in one place, an online journal called The Cochrane Library.

Each Cochrane review is a large published document that brings together and analyses the highest quality research evidence available. At its simplest, a typical Cochrane review starts with a question: does intervention A (e.g. antibiotic) work for health problem B (e.g. an infection) in terms of important outcomes for patients (e.g. cure)?

To answer this question all the controlled trials on the effects of intervention A compared with an alternative intervention or control will be located and summarised in the review. The systematic review concludes with a synthesis of the evidence about the effects of intervention A.

Not all reviews have conclusive findings because the trials may not have been done to answer the question convincingly. But reviews are still valuable because they include useful background information and because they are a comprehensive synthesis and summary of all the relevant research to date. To this end they can help many different people (consumers, health professionals, researchers and policy makers) make important health prevention, treatment, or rehabilitation decisions.


The concept of a systematic review

(click on the diagram to enlarge it)


Our simple conceptual diagram shows the major activities review authors are involved in when they undertake a systematic review, specifically a Cochrane systematic review. It gives a sense of the sifting and sorting, and condensing of information that is involved.














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