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Spinal Cord Injuries: 5 - Boolean, Questions, Filtering, PICO, Special Queries, & Optimization

What are Boolean Operators?

Boolean Operators are words used in searching databases to control how sets of results are/or are not combined. Boolean Operators include

AND        OR       NOT

The Boolean operator -  AND -  intersects concept sets, returning search results that reflect articles which address both concepts. If AND is used, then any article which addresses only one concept will not be included in the search results.

The Boolean operator  - OR  -  unifies concept sets, returning search results that include articles if at least one concept is present. The Boolean operator  - OR - will always expand search results.

The Boolean operator  - NOT  - will exclude articles if the NOT concept is present - do not use the NOT operator without giving it great thought because it is easy to "throw the baby out with the bath water" - in other words, to inadvertently discard articles you may want to look at because the NOT concept term is incidentally present and mixed in with concepts you do want to retrieve.   


View the following tutorial by the USF Polytechnic Library, which relies on visualizations to introduce simple and complex usage of Boolean Operators:


View Emily Mazure's tutorial, which quickly introduces you to the uses of Boolean Operators in searching:



Questions Types

Background VS Foreground Questions -

Background questions are concerned with general information about a condition or disease or topic - causes, symptoms, progression, accepted treatments, outcomes, prevention.

Foreground questions are patient-centered or problem-centered in that the question concerns a specific patient and his/her contexts or a specific problem and its contexts.

For patient-centered questions, these contexts or specific patient characteristics may include comorbidities, demographics, life-cyle stages, life-style, environment, genetic background, epigenetic factors, psychological, sociological, behavioral, economic, anthropological, health delivery context, etc. These question can either be simple or complex, but the focus and application of the answer is the defining feature. As personalized medicine and the development of epigenetic information grows, these foreground questions may become more complex. 

Similarly, problem-centered questions may include elements, which are quite specific to a situation. For example. a patient safety researcher may be interested in developing a procedure for communicating discharge plans or medication monitoring concerns to groups with lower literacy skills or ESL attributes that may need to be specially accomodated. A further example of a patient safety question might concern identifying the kinds of preanalytic errors that occur in the context of blood collection for blood culturing and inquiring whether labs that utilize a hemolysis index in testing improve their rate of error. 

In another sphere of research, a investigator from the field of medical education may wish to study the effects of culture and/or socioeconomic group membership on the perception of costs and expenses associated with medical school might want to see if these effects have been correlated with the "pipeline" of Latino's specifically to medical schools. 


Filtering a simple search

Begin with linking to PubMed (via the UIC LHS Chicago Gateway so that you are connected to all the proxy server identifications needed to access full text)

  • This example demonstrates a simple keyword search in PubMed and the application of a filter to select a particular kind of article.
  • Enter into the PubMed search box our sample search: "preanalytic laboratory errors" - do not include the quotes
  • From the left-column, in the filters section, select "more" under "Article Types" - when the menu selection popup box appears, deselect everything except    "Systematic Reviews" and press the "Show" button
  • Once the menu selection box disappears, click on "Systematic Reviews" so that a check mark appears next to the term (indicating the activation of this Systematic Reviews filter)
  • Your search results are automatically filtered for those documents that are Systematic Reviews (this is indicated by a reduction in the Results number


The P.I.C.O. question is a structured way of asking a foreground or clinical question about a specific patient or group of patients. Please link to LHS PICO tutorial page to read more comprehensively on this topic:


P.I.C.O. Video -

Please see the following 10-minute video by LHS Regional Library Head, Jo Dorsch, provides an excellent introduction to the P.I.C.O. question and its place in the framework of evidence-based medicine:

Special Queries, Clinical Queries, and Optimizing Searches With Pre-determined Filters

PubMed has a page on Special Queries 

Special Queries (SQ) are pre-designed search interfaces that offer pre-designed search filters to find high level evidence in certain topical areas. The oldest is "Clinical Queries" (see immediately below). Another is the "Health Services Research" query (see box below).

Clinical Queries (CQ) is a valuable PubMed search interface that brings specialized pre-designed filters to aid you in getting the highest levels of evidence for patient oriented questions. Each pre-determined filter will retrieve a specific type of study and exclude other types.

PubMed describes the categories of citations the CQ search interface is designed to bring you -

  • "Clinical Study Categories: Find citations corresponding to a specific clinical study category.
  • Systematic Reviews: Find citations for systematic reviews, meta-analyses, reviews of clinical trials, evidence-based medicine, consensus development conferences, and guidelines.
  • Medical Genetics: Find citations related to various topics in medical genetics"

There are a number of ways to get to Clinical Queries online. You can begin at the PubMed main page and look for Clinical Queries under PubMed Tools. Or, you can use the Special Queries page link above. 


The following brief video about Clinical Queries by a U Penn librarian introduces you to CQ from another page

Note, the link to the Haynes' search filters at the bottom of the first column results. Here is a direct link to the Haynes' search filters.

The Haynes search filters, designed by one of the founders of the EBM movement, are joined with your search terms to define very specific evidence retrieval for your search.


Optimization of your search

The following guidance is intended to strengthen your searches and assist you in retrieving more citations.

1. A strong and streamlined rapid search -

a) Search by both MeSH and Keywords - but use the minimun number of concepts needed to identify your intended literature. If you do not retrieve many results, consider looking for additional keywords and MeSH terms (see the Pearling entry below). Search on MeSH terms only (e.g., tag reads [Mesh]) - in other words, use the subheadings or MeSH Major focus selections judiciously.

b) Use the Clinical Queries filters, limit by dates, limit to Core Journals...add filters to reduce the research results. Clinical Queries utilizes special filters developed by Dr. Haynes that allow you to maximize specificity or sensitivity by question type. Remember, unless a filter is critical, specifying it may reduce results in unanticipated ways - e.g., if the indexer neglected to add "Human" as a MeSH term, then a MeSH only search may not retrieve a citaton that is about humans, but not appropriately tagged!

2. Pearling or adding to your search terminology - You can add to your search term list by looking at the indexing for any articles that capture the content you are focused on. You can also look at the articles cited by or citing your prize article. This puts you in touch with the researchers who may be on the same investigative thread.

3. Systematic Reviews.  Note, systematic reviews often focus on clinical questions and are useful for immediate medical decision making. However, they are comprehensive reviews of the literature that must be scrutinized for timeliness. For example, a systematic review may have been published in 2013, but the underlying searches comprising the review may have concluded in early 2012 or before. Check the most current literature to be sure a significant study was not published after the search window of a systematic review closed. Since systematic reviews publish their search strategies, you can simply use the strategy that the systematic review employed to update your own search on an informal basis. Note, the use of systematic review search strategies in publications requires attention to issue of attribution.