Filters (also called hedges) are used to narrow a search and/or focus in on a specific publication type, level of evidence, and/or subject area. Filters are constructed using specific database syntax (rules and commands). Strategies are developed with rules and commands used to search a variety of databases and interfaces including PubMed, Ovid, Embase, and CINAHL. Some filters are adjusted to be more sensitive (accurate identification) or specific (accurate exclusion).
Several research and healthcare groups produce pre-tested strategies that identify high quality evidence or focus in on a particular health care field or area. Using pre-existing filters or strategies can assist in managing the vast amounts of literature indexed in the major medical databases, and provide you with a smaller number of articles to start with when searching.
While it is important to be aware of the authority and accuracy of a specific filter, using a filter that has not been validated or tested is not incorrect. It is important to recognize and identify the impact that using a particular filter may have on your search results. If a particular filter works well in a given context and does not appear to be producing a high number of irrelevant results or excluding relevant items, by all means use that filter.