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Cochrane Library features Cochrane Reviews--systematic reviews of the literature. You won't get the most hits in this database, some of you won't find anything at all, but if you do it will be high-quality.
There are a couple of ways to go about this.
1. In the top search box, type in your patient characteristic, the intervention(s) you are considering, and/or the outcome you wish. Note that often you won't get results with all three, be prepared to reduce specifics to get more articles to choose from.
2. If you click "Advanced Search," you will see Cochrane has a PICO search beta. Beta means they are testing it and it might not be quite ready. But it can be interesting to see how they assign PICO keywords.