The Cochrane Wounds Group

Introduction: The Cochrane Collaboration is an international collaboration
concerned with preparing, maintaining and
promoting the accessibility of systematic reviews of the
effects of health care interventions.
People who make decisions about health care, patients,
clinicians and managers, are often faced with a mass of
information reporting on treatments and ways of delivering
care. Systematic reviews use explicit objectives and
methods to synthesise the results of primary research.
They integrate what can sometimes be a mass of information,
taking into account any differences and similarities
between the original studies. Cochrane Systematic
Reviews are only concerned with the effects of health
care interventions, and therefore they normally consider
evidence gathered from randomised controlled trials.
Systematic reviews can include other forms of evidence,
eg where the question is about prognosis, diagnosis, or
patients perceptions. In some cases, it may be possible to
combine the results of a number of randomised controlled
trials using a statistical technique called metaanalysis.
This can only be done when there are similar
patients, treatments and outcomes. It can be thought of
as treating different trials as part of one large trial.
Meta-analysis is useful because many small trials may
fail to find a difference in effectiveness even when one
exists, simply because they were too small. By combining
trials, it is possible to determine whether there really is a
difference in effectiveness. In many reviews, however, it
is not appropriate to combine studies and so a narrative
review is completed.