I can recommend using the Joanna Briggs Institute EBP database. It prescribes levels of evidence for single studies and systematic reviews as well as gives a good EBP summary for interventions.
Here's a quick video on how to access and use the JB database (view in Chrome): http://somup.com/cqQYIgeCdx. It's a quick search; I narrowed my results to Evidence Summaries. JBI also grades the randomized control trials reviewed in it's systematic reviews.
JBI grades levels of evidence. 1 being high level(systematic review) to 5 being low level of evidence (expert opinion).
This is a quick video on narrowing to EBP article types in PubMed (view in Chrome): http://somup.com/cqQYIdeCdR
Anthony
anthony.micchelli@va.gov