Specialized databases of evaluated abstracts, commentary, and systematic reviews are another source for high levels of evidence and best studies.
Authors of a systematic review ask a specific clinical question, perform a comprehensive literature search, eliminate the poorly done studies and attempt to make practice recommendations based on the well-done studies. A meta-analysis is a systematic review that combines all the results of all the studies into a single statistical analysis of results.
Systematic Reviews and Meta-Analyses are also searchable in MEDLINE, CINAHL, PsycINFO, Proquest, and other databases, using filters: