A Systematic Review (SR) is a compilation of the data from all the research trials (which meet certain predefined criteria) studying a particular topic, for example, acupuncture for treating lower back pain or pelvic pain during pregnancy. The studies are always Randomized Controlled Trials (RCT’s), seen as the “gold standard” in a clinical study. The authors look at all the existing studies, examine their similarities and differences, and perform a statistical analysis of the results. This allows more certain conclusions to be drawn since there’s a larger pool of data. The larger the pool of data, generally the more certainty we have that the results are not due to chance. Different groups of authors might all write their own SR on a particular topic, and as new studies are published, new SR’s will be published.

This is not to say that a Systematic Review’s conclusions are set in stone: some of these papers have problems with the way they were written or analyzed the data, or they might still be based on a relatively small amount of information. However they are an important part of performing research and hold more weight than any single research study.

A Cochrane Review is a systematic review on a topic in health care which is written according to certain criteria set forth by Cochrane. It’s generally seen as the highest quality type of Systematic Review, and only looks at RCT’s. There is a Cochrane Review available for almost any health care topic, and they are usually updated every few years as new research becomes available. The authors of a Cochrane Review follow a specific procedure in choosing their subject matter, the evidence included and the way it’s analyzed and reported. The SR is reviewed by the Cochrane Editorial Board for quality and accuracy. The authors are independent and Cochrane does not accept commercial funding or any funding that might pose a conflict of interest.

One aspect of Cochrane Reviews that I appreciate is that they make free plain-language summaries available for each topic. So even if you aren’t a researcher, you can search for a summary and understand what conclusions have been made and why.

Cochrane reviews do not address the quality of the intervention- meaning, how applicable it was to real-life practice. For more information on this issue, see the next section. Also, it’s important to remember that Cochrane reviews only include Randomized Controlled Trials, not other types of studies. These other studies may still have value and lend an important contribution to the body of evidence, so keep in mind that outside of the Cochrane review there may be other important information to consider.