National Collaborating Centre for Methods and Tools

What’s the difference between a systematic review and a literature review or a review of the literature? I find literature reviews easier to read, I don’t get as bogged down with the details provided in the systematic review.

Systematic reviews and literature reviews are different.
A systematic review is a consolidation of the literature on a specific topic or question. Individuals involved in conducting a systematic review go through a specific, methodological process which includes a number of steps:
1. Conducting a comprehensive search to identify potential studies, both published and unpublished
2. Reviewing all studies to determine if they are relevant to the question being asked
3. Evaluating the methodological quality of the studies that were found to be relevant
4. Extracting the data from each of the studies
5. Analyzing the data
6. Drawing conclusions

Typically, steps 2, 3 and 4 are done by two people independently who then compare their ratings and discuss any disagreements. If step 5 involves the statistical compilation of data, the systematic review becomes a meta-analysis. So all meta-analyses should be systematic reviews, but not all systematic reviews are meta-analyses.

Donna

After reading this discussion thread, I was interested in the topic and did a quick search on health-evidence.ca to find the systematic review that was cited (Jefferson et al., 2009). I found two reviews by the same author with the same title. One was dated in 2009 and the other was 2010. Which one should I use?

Thanks for picking up the discussion again. That’s a great question. In this case, the 2009 BMJ article summarized key points from a 2007 Cochrane Collaboration systematic review. The Cochrane review has since been updated and published again in 2010. If you look closely at the methods section of each paper, you will see that in 2010, one additional study was included in the results.

Health-Evidence.ca has reviewed, and rated the 2010 updated review and has created a summary statement. The summary statement is a short report that identifies the key findings of a review and links the evidence to ‘actionable’ implications for public health. This would be an excellent resource to review.

If we were to continue on with the evidence-informed decision making process (EIDM) from where this thread left off, we would have just completed appraising the quality of evidence and be ready for the synthesis step. Would you be interested in continuing on with this illustration?

Sure, this example is actually very relevant to work that I am doing now at my public health unit. I would be interested to work through the remaining steps with you.

Great! At the synthesis step, you will need to make sense of conflicting reviews or study findings and determine the ‘actionable’ messages. For example, some studies may conclude that more research is needed, that is, there is no strong evidence to support or negate a claim that the intervention works. In this case there is no clear “actionable” message.

If there are conflicting findings across reviews or studies, you will need to consider the quality (which source is the highest quality), date of publication (which is most recent) and applicability to your population and access to necessary resources as a way of prioritizing which result(s) to use. Then determine the key “actionable” messages.

In this particular example using the 2010 systematic review and summary statement that you have found, what do you think the actionable messages are?

Sure, I could try to figure out what the “actionable messages” are within the review, but first, would you be able to explain what you mean by “actionable messages”?

“Actionable messages” are actions that can be concluded from the results of a systematic review or an individual study, beyond “more research needed”. They can be thought of as the ‘take home’ messages from the article that can be applied in practice.

Looking back at the Health Evidence summary statement, I would conclude that hand washing and wearing masks, gloves, and gowns were each effective in preventing the spread of respiratory viruses, but even more effective when used in combination. Individuals suspected of respiratory tract infections should be isolated and programs should target reducing transmission from children to other groups (e.g., families, teachers, etc.). Public health programs should educate and provide instruction on the importance of hand hygiene and physical barriers.

What do you think?

Absolutely. There are strong “actionable” messages in this review, and you picked out key ones related to our scenario.

The next step would be to adapt this recommendation to your own public health environment. At this step, you will be answering the question “can I use this research evidence in my community or with a particular population?”

How would you adapt these recommendations to your community? Who would be your local target audience?