Constructing effective search strategies is perhaps even more of an art than constructing effective clinical questions. Luckily, medical librarians are experts at this and should be your first stop. Not only can skilled medical librarians help you with your searches, they can also teach you efficient ways to conduct simple searches yourself. I will mention a few of these strategies, but these are truly only the tip of the iceberg.
The key elements of searching the large medical information databases such as MEDLINE include an understanding of Medical Subject Headings (MeSH), text-word searching, and combining searches. Mapping to a MeSH term and clicking the “explode” option on the search page will gather not just those papers indexed to the term of interest, but also papers referencing more specific aspects of that term. Clicking on the search term itself will reveal the “tree” of terms related to your chosen search term. For example, try searching MEDLINE for “cancer.” You will be mapped to “neoplasms,” and if you click on that term, you will see a tree of related terms. If you select “explode” for your initial search, you will include each of these related terms, expanding your search. You could also narrow your search by selecting “neoplasms by site” or another subheading, and further refining your approach from there.
To begin a search, it is helpful to first enter in relevant keywords from your clinical question. Following our previous example, these could include renal cell carcinoma, chemotherapy, and survival. Then you could perform one search for each term, combining them using the search window options. Alternatively, each term could be linked in one search using the AND/OR operators. Further restrictions such as looking only at randomized controlled trials or for specific authors are also possible. Finally, many MEDLINE sites have a collection of saved search strategies for common clinical question types. For example, a saved search strategy for articles on diagnosis (or therapy, prognosis, or any other question type) can provide an effective searching technique based on the expertise of your resident search professional.
Because many of these approaches rely on the way in which an article has been indexed, searching for synonyms can also be helpful. You may search for temporal arteritis and miss articles indexed only under giant cell arteritis, for example. MEDLINE does a good job of mapping these terms to each other, but this can fall short, particularly if you search by text word alone. Being clever with synonyms can be the difference between finding and missing the one key article that will answer your clinical question.
Searchable Sources of Medical Information
“Overview of Searchable Sources of Medical Information” (p. 18) presents a brief overview of searchable sources of information. Becoming a searching expert takes considerable dedication, but fortunately the basic strategies are not overly complicated. Additionally, significant efforts are being made to simplify the steps needed to answer clinical questions, as can be seen in the growing number of secondary journals available for both general medicine and subspecialties.
Searching for the answers to well-constructed clinical questions is obviously a crucial step in the EBM process. Well-built questions suggest efficient search strategies, simplifying what can be a complex and daunting process. Many resources are available to help with this step, including medical librarians, prefiltered searches, and saved searches for common query types. Once you locate an article addressing your clinical question, the next step is to critically appraise the article to determine whether its results are applicable to your patient. TH