Hedges, limits, and filters: The keys to efficient searching

In searching the medical literature, one of the dilemmas most frequently encountered is that of being overwhelmed by too much in­formation. For example, in looking for high-quality references in Medline on the best treatment protocol for Crohn’s disease, optimizing the search process begins with logging in to the database through one of the interfaces available through the College Library. Accessing PubMed, Ovid Medline, or EBSCO in this way links the search to the full text of articles available through the library’s online subscriptions. 

Entering the term “Crohn disease,” then clicking on therapy subheadings further defines the search. Retrieval at this step is in the thousands, so using hedges, limits, and filters helps the user to zero in on the most evidence-based information. The easiest way to determine which limits to use, and in what order, is to consider their importance to the search. For example, if it is crucial that articles are in English, discuss human subjects, and are recently published, begin with those limits. 

Next, a number of quality hedges can be employed to narrow the still large number to the very best references. Selecting the limit “evidence-based medicine reviews” limits results to Cochrane topic reviews, the articles used in those reviews, and some other evidence-based resources. Choosing “clinical queries” allows the searcher to filter diagnosis and treatment results with a balance of sensitivity and specificity. The subject subset “systematic reviews” and the publication type “meta-analysis” are also useful tools to limit retrieval to the highest quality articles. 

Before laboriously browsing through hundreds of references, try some of Medline’s limit functions to select the articles that are best for you. Using hedges, limits, and filters for best treatment of Crohn’s disease narrowed the original list of over 10000 citations to a more easily browsed 50—a much better use of the busy physician’s time.
—Karen MacDonell
—Robert Melrose
—Judy Neill

This article is the opinion of the Library of the College of Physicians and Surgeons of BC and has not been peer reviewed by the BCMJ Editorial Board.

Karen MacDonell, PhD, MLIS, Robert Melrose, Judy Neill. Hedges, limits, and filters: The keys to efficient searching. BCMJ, Vol. 54, No. 10, December, 2012, Page(s) 497 - College Library.

Above is the information needed to cite this article in your paper or presentation. The International Committee of Medical Journal Editors (ICMJE) recommends the following citation style, which is the now nearly universally accepted citation style for scientific papers:
Halpern SD, Ubel PA, Caplan AL, Marion DW, Palmer AM, Schiding JK, et al. Solid-organ transplantation in HIV-infected patients. N Engl J Med. 2002;347:284-7.

About the ICMJE and citation styles

The ICMJE is small group of editors of general medical journals who first met informally in Vancouver, British Columbia, in 1978 to establish guidelines for the format of manuscripts submitted to their journals. The group became known as the Vancouver Group. Its requirements for manuscripts, including formats for bibliographic references developed by the U.S. National Library of Medicine (NLM), were first published in 1979. The Vancouver Group expanded and evolved into the International Committee of Medical Journal Editors (ICMJE), which meets annually. The ICMJE created the Recommendations for the Conduct, Reporting, Editing, and Publication of Scholarly Work in Medical Journals to help authors and editors create and distribute accurate, clear, easily accessible reports of biomedical studies.

An alternate version of ICMJE style is to additionally list the month an issue number, but since most journals use continuous pagination, the shorter form provides sufficient information to locate the reference. The NLM now lists all authors.

BCMJ standard citation style is a slight modification of the ICMJE/NLM style, as follows:

  • Only the first three authors are listed, followed by "et al."
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For more information on the ICMJE Recommendations for the Conduct, Reporting, Editing, and Publication of Scholarly Work in Medical Journals, visit www.icmje.org

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