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Strategies for Searching the Literature Using PubMed

Course Number: 340

Searching with PubMed Clinical Queries

Now that the basics of PubMed have been reviewed, rather than beginning a PubMed search on the homepage using a traditional or comprehensive approach, a valuable feature for answering clinical questions for busy professionals and students is PubMed Clinical Queries. Click on the link found on the Homepage under PubMed Tools (Figure 1). The Clinical Queries feature (Figure 13) provides specialized searches using evidence-based filters to retrieve articles. The built-in evidence-based algorithms streamline the process of searching for clinically relevant articles.

Image: PubMed Clinical Queries

Figure 13. PubMed Clinical Queries.

Of the options on the Clinical Queries page, our focus is on using the main search bar and the Clinical Study Categories. Special algorithms are designed to find relevant evidence under the each Category.  The default category is Therapy, however by clicking on the drop-down menu, other categories are found, such as Clinical Prediction Guides, Diagnosis, Etiology, and Prognosis. These can be searched with a broad or narrow focus. Broad is the default so by using the drop-down menu  narrow can be selected.

Clinical Queries allows an individual with limited computer searching skills to find high levels of evidence by typing in a main topic or specific terms of interest. Using the same clinical scenario, "tooth erosion OR erosive tooth wear" is typed into the search box (Figure 14).

Image: Results of Searching for Tooth Whitening
Image 2 of Clinical Queries Results of Searching for Tooth Erosion OR Erosive Tooth Wear

Figure 14. Clinical Queries Results of Searching for Tooth Erosion OR Erosive Tooth Wear.

In this case, 1739 results were retrieved under a broad scope and 225 results under a narrow scope in Clinical Study Categories. To further narrow these, include Stannous fluoride (I) AND (Potassium nitrate AND sodium fluoride) AND toothpaste (C), Figure 15a.

Image: Clinical Study Categories Results using a Narrow Scope for Tooth Whitening
Image 2 of Clinical Queries Results of Searching for the P, I and C components

Figure 15a. Clinical Queries Results of Searching for the P, I and C components.

In this case, 2 were found using the Narrow Scope and 4 were found using the Broad Scope.  These same studies are found under the Advanced Search Builder, Figure 7, result #8. Therefore, it is possible in two steps using Clinical Queries (vs. 7 steps and the use of Boolean operators, Figure 7a) to identify relevant studies to answer the question.

Review the abstracts found under the Clinical Study Categories. This search uses evidence-based search filters to find individual studies in the indicated category. The default settings are ‘Therapy’ under Category and ‘Broad’ under Scope, since the majority of questions asked fall under the category of therapy. The type of studies retrieved for this category and scope are randomized controlled trials (see filter table link at bottom of the webpage). If there were hundreds of studies, then change the Scope to Narrow (Figure 15b) and this will reduce the number of citations. A Narrow, specific search will return the most relevant citations, although it may miss some.

Image: Narrow Search Under Clinical Study Category for Crest Whitestrips and Custom Tray Bleaching

Figure 15b. Clinical Study Categories: Changing the Scope from Broad to Narrow.

In our case, with only 4 citations returned, there was no need to change the scope from Broad to Narrow. However, our graphic shows that a narrow search reduces the results to 2 citations.

Another important consideration is the type of question/category for which an answer is being sought, i.e., does the question pertain to etiology (or harm), diagnosis, therapy, prognosis or clinical prediction guides (Figure 16). Make sure the correct category is checked off.

Image: Type of Question/Category

Figure 16. Clinical Study Categories: Changing the Category from Therapy.

Although there is no one correct way to conduct a search, how search terms are entered influences the results and the number of steps needed to refine the search.