This is an archived version of the Handbook. For the current version, please go to or search for this chapter here.

Search filters are search strategies that are designed to retrieve specific types of records, such as those of a particular methodological design. They may be subjectively derived strategies such as the original Cochrane Highly Sensitive Search Strategy for identifying reports of randomized trials in MEDLINE (Dickersin 1994) or they may be objectively derived by word frequency analysis and tested on data sets of relevant records to assess their sensitivity and precision, such as the search strategies below for identifying randomized trials in MEDLINE (Glanville 2006). Recently a search filters web site has been developed by the UK InterTASC Information Specialists Subgroup (ISSG), which is the group of information professionals supporting research groups within England and Scotland providing technology assessments to the National Institute for Health and Clinical Excellence (NICE) (Glanville 2008). The purpose of the web site is to list methodological search filters and to provide critical appraisals of the various filters. The site includes, amongst others, filters for identifying systematic reviews, randomized and non-randomized studies and qualitative research in a range of databases and across a range of service providers.


Search filters should be used with caution. They should be assessed not only for the reliability of their development and reported performance but also for their current accuracy, relevance and effectiveness given the frequent interface and indexing changes affecting databases. The ISSG offer a search filter appraisal tool to assist with assessing search filters and examples can be seen on the web site: