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Systematic Searching Support


The use of database limits is generally discouraged because most limits operate based on the indexing applied to individual records and use of them may compromise the sensitivity of the search. Custom search filters (hedges) created and tested for use in systematic reviews may be of value. The research units below have made their filters available Contact us for additional help locating or applying filters that do not use database limits (i.e., do not operate on database indexing).

Examples of Commonly Used Hedges/FIlters

Limit to Human Studies in PubMed

 NOT ("Animals"[Mesh] NOT ("Animals"[Mesh] AND "Humans"[Mesh]))

Limit to Randomized Controlled Trials in PubMed

 clinical[tiab] AND trial[tiab] OR "clinical trials as topic"[mesh] OR "clinical trial"[pt] OR random*[tiab] OR "random allocation"[mesh] OR "therapeutic use"[sh]


Articles about Hedges/Filters

  • DeJean D, Giacomini M, Simeonov D, & Smith A. Finding qualitative research evidence for health technology assessment. Qual Health Res. 2016:26(10):1307-1317. 
  • Kastner, M., Wilczynski, N. L., Walker-Dilks, C., McKibbon, K. A., & Haynes, B. (2006). Age-specific search strategies for Medline. Journal of Medical Internet Research, 8(4), e25. 
  • McKibbon, K. A., Lokker, C., Wilczynski, N. L., Haynes, R. B., Ciliska, D., Dobbins, M., Davis, D. A., & Straus, S. E. (2012). Search filters can find some but not all knowledge translation articles in MEDLINE: an analytic survey. Journal of Clinical Epidemiology, 65(6), 651-659. 
  • McKibbon, K. A., Wilczynski, N. L., & Haynes, R. B. (2009). Retrieving randomized controlled trials from medline: a comparison of 38 published search filters. Health Info Libr J, 26(3), 187-202. 
  • Shaikh, N., Badgett, R. G., Pi, M., Wilczynski, N. L., McKibbon, K. A., Ketchum, A. M., & Haynes, R. B. (2011). Development and validation of filters for the retrieval of studies of clinical examination from Medline. Journal of Medical Internet Research, 13(4), e82. 
  • Wilczynski, N. L., Marks, S., & Haynes, R. B. (2007). Search strategies for identifying qualitative studies in CINAHL. Qualitative Health Research, 17(5), 705-710.