Systematic reviews of all the relevant, reliable evidence

Whilst it is easy to state that we should review the results of a particular study alongside other relevant, reliable evidence, this is a challenge in many ways. Reviews are important because people should be able to depend on them, and that means that they must be done systematically, otherwise they will be misleading.

Systematic reviews addressing what appears to be the same question about treatments may reach different conclusions. Sometimes this is because the questions addressed are subtly different, or because the methods used by the researchers differed; and sometimes it is because the researchers have introduced ‘spin’ in their conclusions.

So, it is important to identify reviews that address the treatment questions that match those we are interested in; which are most likely to have been prepared in ways that reduce the effects of biases and the play of chance successfully; and which reach honest conclusions, in ways that reflect the evidence presented.

In this section

• Reducing biases in systematic reviews
• Identifying all the relevant evidence for systematic reviews
• Reducing the play of chance in systematic reviews
• Recognizing vested interests and spin in systematic reviews