Retrieving clinical evidence: a comparison of PubMed and Google Scholar for quick clinical searches.
BACKGROUND
Physicians frequently search PubMed for information to guide patient care. More recently, Google Scholar has gained popularity as another freely accessible bibliographic database.


OBJECTIVE
To compare the performance of searches in PubMed and Google Scholar.


METHODS
We surveyed nephrologists (kidney specialists) and provided each with a unique clinical question derived from 100 renal therapy systematic reviews. Each physician provided the search terms they would type into a bibliographic database to locate evidence to answer the clinical question. We executed each of these searches in PubMed and Google Scholar and compared results for the first 40 records retrieved (equivalent to 2 default search pages in PubMed). We evaluated the recall (proportion of relevant articles found) and precision (ratio of relevant to nonrelevant articles) of the searches performed in PubMed and Google Scholar. Primary studies included in the systematic reviews served as the reference standard for relevant articles. We further documented whether relevant articles were available as free full-texts.


RESULTS
Compared with PubMed, the average search in Google Scholar retrieved twice as many relevant articles (PubMed: 11%; Google Scholar: 22%; P<.001). Precision was similar in both databases (PubMed: 6%; Google Scholar: 8%; P=.07). Google Scholar provided significantly greater access to free full-text publications (PubMed: 5%; Google Scholar: 14%; P<.001).


CONCLUSIONS
For quick clinical searches, Google Scholar returns twice as many relevant articles as PubMed and provides greater access to free full-text articles.
Kidney Clinical Research Unit, Division of Nephrology, Western University, London, ON, Canada. salimah.shariff@lhsc.on.ca
Salimah Z
SZ
Shariff
Shayna Ad
SA
Bejaimal
Jessica M
JM
Sontrop
Arthur V
AV
Iansavichus
R Brian
RB
Haynes
Matthew A
MA
Weir
Amit X
AX
Garg
D016208:Databases, Factual; D019317:Evidence-Based Medicine; D016247:Information Storage and Retrieval; D020407:Internet
Google Scholar; PubMed; information dissemination/methods; information storage and retrieval; library science; medical; nephrology