Search filters are pre-tested strategies that identify the higher quality evidence from the vast amounts of literature indexed in the major medical databases. Filters exist for most types of experimental design, and are comprised of index terms relating to study type and specific terms associated with the methodological description of good experimental design.
The search filters used by SIGN are developed in-house or are created by other research organisations and adapted to meet SIGN information needs. SIGN's filters may provide less sensitive searches than used by other systematic reviewers such as The Cochrane Collaboration, but enable the retrieval of medical studies that are most likely to match SIGN's methodological criteria.
SIGN has devised suitable strategies for running each search filter in Ovid implementations of Medline, Embase and CINAHL along with other more specialised databases. The following is an explanation of some of the search devices commonly used in SIGN filters:
/ after an index term indicates that all subheadings were selected.
* before an index term indicates that that term was focused - i.e. limited to records where the term was a major MeSH/Emtree term.
"exp" before an index term indicates that the term was exploded.
.tw. indicates a search for a term in title/abstract
.mp. indicates a free text search for a term
.pt. indicates a search for a publication type
$ at the end of a term indicates that this term has been truncated.
? in the middle of a term indicates the use of a wildcard.
adj indicates a search for two terms where they appear adjacent to one another.”