Chapter 3: Finding Relevant
Evidence to Answer Clinical
Questions
Copyright © 2011 Wolters Kluwer Health | Lippincott Williams & Wilkins
Answering Clinical Questions


Finding the right information to answer a given question
often depends on the source of the information
Searching for evidence that has already been appraised
for the quality of the study methodology and the
reliability of its findings is desirable

Pre-appraised literature
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Tools for Answering Clinical Questions


Begin with a PICOT question
Determine the source from which the best evidence is
available

Clinicians need peer-reviewed research
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External Sources of Evidence

Textbooks and journals

Consolidated resources
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Hierarchy of Evidence
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Question

Which of the following sources of evidence is best able to
inform a nurse’s clinical practice?
a. A well-designed randomized controlled trial (RCT)
b. A systematic review that encompasses multiple studies
c. Expert opinion of experienced and educated nurses
d. A case study that addresses an unique clinical scenario
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Answer


b. A systematic review that encompasses multiple studies
Rationale: Systematic reviews are considered to be
higher on the hierarchy of evidence than expert opinion
or individual RCTs and case studies.
Copyright © 2011 Wolters Kluwer Health | Lippincott Williams & Wilkins
Which Resource or Database is a Good
Match?

Online databases

Grey literature

Bibliographic versus full-text databases
Copyright © 2011 Wolters Kluwer Health | Lippincott Williams & Wilkins
Collaboration with Healthcare Librarians

Librarians are a rich source of assistance

They are especially valuable when time is of the essence
Copyright © 2011 Wolters Kluwer Health | Lippincott Williams & Wilkins
Keyword and Controlled Vocabulary
Searching


Keyword searching is searching using simple, everyday
language
Controlled vocabulary systems, e.g., MeSH


Normally have a hierarchical structure that helps the
searcher retrieve the more specific terms that fall
under a general term
Most large bibliographic databases (MEDLINE, CINAHL,
and PsycINFO) use a controlled vocabulary to describe
the content of references
Copyright © 2011 Wolters Kluwer Health | Lippincott Williams & Wilkins
Question


Tell whether the following statement is true or false.
A controlled-vocabulary system may yield fewer hits than
a keyword search, but these hits are more likely to be
relevant to the clinical question.
Copyright © 2011 Wolters Kluwer Health | Lippincott Williams & Wilkins
Answer


True
Controlled vocabulary systems exist to increase the
relevance of search results while limiting the number of
less-relevant hits.
Copyright © 2011 Wolters Kluwer Health | Lippincott Williams & Wilkins
Combining and Limiting Searches




Combining search terms from within a PICOT question
focuses the search results
Consider that different search engines process terms in
the search box in different ways
Using the “limit” function is designed to help the searcher
pare down the large results list
Manage inclusion and exclusion criteria carefully
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Online Searches

Managing citations

Saving searches

Organizing searches
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Selecting Databases: Cochrane
Databases



A collection of 6 different databases
“Gold standard” database is the Cochrane Database of
Systematic Reviews (CDSR)
Systematic reviews are based on critical appraisal
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Selecting Databases: National Guideline
Clearinghouse


A comprehensive database of evidence-based clinical
practice guidelines
Guidelines are systematically developed statements
about a plan of care for a specific set of clinical
circumstances involving a particular population
Copyright © 2011 Wolters Kluwer Health | Lippincott Williams & Wilkins
Selecting Databases
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
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
MEDLINE - covers medicine, health, and the biomedical
sciences
CINAHL – covers 13 nursing and allied health disciplines
EMBASE - major European biomedical and
pharmaceutical database
PsycInfo – covers psychology, behavioral sciences, and
mental health
Copyright © 2011 Wolters Kluwer Health | Lippincott Williams & Wilkins
Question

Which of the following online evidence sources is most
likely to provide pre-appraised evidence?
a. CINAHL
b. MEDLINE
c. PubMed
d. Cochrane Library
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Answer


d. Cochrane Library
Rationale: The Cochrane Databases consist of systematic
reviews that synthesize evidence from multiple peerreviewed sources. CINAHL, MEDLINE, and PubMed may
contain evidence at a synthesis level, but are more often
sources of individual articles that a nurse must appraise.
Copyright © 2011 Wolters Kluwer Health | Lippincott Williams & Wilkins
Specialized Search Functions

PubMed

Ovid

EBSCO
Any search for evidence must be followed by critical
appraisal
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