5 Searching for Evidence 85
MEDLINE, available for free through the National Library of Medicine’s inter-
face, PubMed, contains over 26 million references to journal articles in the life
sciences with a concentration on biomedical research. One of MEDLINE’s most
notable features is an extensive, controlled vocabulary: Medical Subject Headings
(MeSH). Each record in MEDLINE is reviewed by an indexer who is a specialist
in a biomedical field. The indexer assigns an appropriate MeSH heading to every
record, which allows for precise searching by eliminating irrelevant articles where
a keyword may be casually mentioned. A common saying in the library world is:
“Garbage in, garbage out.” MeSH can eliminate “garbage,” or irrelevant articles.
To search in PubMed using the PICO example for distractions during medica-
tion administration, one would use the MeSH for “Medication Errors” [MeSH].
MeSH has no term for “distractions,” but distraction as a keyword can be used.
The related MeSH term of “Attention” [MeSH] could also be considered. The
search strategy would look like this: (“Medication Errors”[MeSH] OR “medica-
tion errors”[All Fields]) AND (“Attention”[MeSH] OR distraction [All Fields]).
PubMed also contains Clinical Queries, which has prebuilt evidence-based filters.
Clinical Queries uses these filters to find relevant information on topics relating
to one of five clinical study categories: therapy, diagnosis, etiology, prognosis, and
clinical prediction guides. Clinical Queries also includes a search filter for system-
atic reviews. This filter combines search terms with a filter that limits results to
systematic reviews, meta-analyses, reviews of clinical trials, evidence-based medi-
cine, consensus development conferences, and guidelines.
The Cochrane Library
The Cochrane Library is a collection of databases that most notably includes
the Cochrane Database of Systematic Reviews. Internationally recognized as the
gold standard in evidence-based health care, Cochrane Reviews investigate the
effects of interventions for prevention, treatment, and rehabilitation. They also
assess the accuracy of a diagnostic test for a given condition in a specific patient
group and setting. Over 6,900 Cochrane Reviews are currently available and as
many as 2,450 protocols. Abstracts of reviews are available free of charge from
the Cochrane website; full reviews require a subscription. A medical librarian can
identify the organization’s access to this library.
