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Skip to Main ContentOften called Search Filters or Search Hedges, these are search terms that have been thoroughly tested and can be added to your search to identify certain types of articles, i.e., randomized controlled trials.
Published, highly sensitive, validated strategy filters should be used to identify randomized controlled trials. Search Filters, or Hedges, provide "canned" queries which are meant to target/identify certain types of research articles. ThePublic Services Division at the National Library of Medicine offers PubMed Health Services Research (HSR) Queries which can be either sensitive/broad in their search results or specific/narrow.
For more information, please see the NLM site for PubMed HSR Queries.
McKibbon KA, Wilczynski NL, Haynes RB; Hedges Team. Retrieving randomized controlled trials from medline: a comparison of 38 published search filters. Health Info Libr J. 2009 Sep;26(3):187-202. doi: 10.1111/j.1471-1842.2008.00827.x. PMID: 19712211.