© 2006 1 literature searching a literature search identifies relevant information sources that are...

1© 2006

Literature searching

A literature search identifies relevant information sources that are used to

answer clinical questions

Evidence-based Chiropractic 2 © 2006

PubMed searching

• Search using keywords, text words, or subject headings– PubMed looks for entered keywords or text

words in each of the possible fields of a record

– e.g., author, title, abstract, journal name, volume, issue, date, etc.


Features barFeatures bar

Query boxQuery box

SidebarSidebar

Search dropdown list

Search dropdown list


• Search terms are typed into the Query box

• The Search drop-down list is typically left in its default position

• The MeSH database can be searched from the Search drop-down list orusing a link in the sidebar

PubMed homepage

Headache


PubMed sidebar

The tutorial is excellent

The tutorial is excellent

Link to the MeSH Database

Link to the MeSH Database

Clinical Queries link

Clinical Queries link


• The Clinical Queries link permits searches designed to answer clinical questions– Topics can be searched by clinical study

categories (e.g., therapy, diagnosis, prognosis, etc.)

– Or to only search for systematic reviews

PubMed sidebar (cont.)


PubMed Clinical Queries search

Select studycategory

Search term


• The MANTIS High Clinical Relevancy option is similar to PubMed’s Clinical Queries

• High Clinical Relevancy limits a search to articles that involve clinical trials or case reports

MANTIS


MANTIS advanced search page

Search term

High Clinical Relevancy check box

High Clinical Relevancy check box

MANTIS Advanced search screen

MANTIS Advanced search screen


PubMed Basic Search mode

• Simply enter search terms in the Query box and click Go

• PubMed produces a list of retrieved citations

• Stopwords are ignored by PubMed– e.g., the, and, because, thus, etc.– They don’t add or detract anything from the

search results


Search results for chiropractic

Search results for chiropractic

Click to see full citation

Click to see full citation

Check box then click Display

Check box then click Display


Select format for display view

Select format for display view

Sort records by option

Sort records by option

Results can be sent

Results can be sent


Multiple checkboxes

• More than one record can be viewed at the same time by selecting the checkboxes next to the desired citations – Select a drop-down menu choice to set the

display format

• PubMed keeps track of checkboxes and displays all checked records when requested by clicking Display


Advanced PubMed search tactics

• Limits– Click the Limits tab on the Features bar

• Select the limiting search criteria from the screen that appears


More limit criteria


Limits (cont.)

• Searching with limits will only retrieve articles that meet the limiting criteria that are set

• Selecting from the Type of article menu limits searches to specific publication types– e.g., meta-analyses, clinical trials, case

reports, editorials, etc.


Limits example

• A search using the terms carpal tunnel syndrome without limits yields 5,728 citations―far too many to contend with

• Whereas only 15 are retrieved when the following limits are set– English– Clinical Trial – Complementary Medicine


Field tags

• Used to refine searches by forcing the query to consider specific search fields

• Results are very similar to what is achieved using Limits– Thus, field tags are optional in PubMed – Some think field tags are easier to use and

prefer them

• Limits function is only partial in MANTIS


Field tags (cont.)

• Field tags are placed within brackets after search terms– Does not matter how many spaces between

the search term and the field tag– Does not matter whether upper or lower case

letters are used

• To use field tags – Enter the search term in the query box

followed by a field tag within brackets


Common PubMed Field Tags

Affiliation [AD]

Author Name [AU]

Journal Title

Abbreviation [TA]

Language [LA]

MeSH Terms [MH]

Publication Date [DP]

Page Number [PG]

Publication Type [PT]

Volume [VI]

Issue [IP]

Subset [SB]

Text Words [TW]

Title Words [TI]


Field tags example

• If spinal stenosis is searched for in PubMed– Without any field tags, 2960 citations result

• spinal stenosis

– Using the Title Words [TI] field tag, only 731 • spinal stenosis [TI]

– Combined with Author Name [AU], only 4• spinal stenosis [TI] smith [AU]


Boolean (Logical) operators

• Words that combine search terms to narrow down or broaden searches

• Consist of AND, OR, and NOT – Should always be capitalized

• Used by many databases, including PubMed and MANTIS


Boolean operator AND

• AND limits or narrows down a search

• Combines terms so that only citations that contain both terms are retrieved

• For example – A PubMed search for sacroiliac joint yields

2,760 citations and manipulation 33,819– Searching sacroiliac joint AND manipulation

narrows the results down to 76


sacroiliac joint 2,760 citations

manipulation 33,819 citations

AND example

sacroiliac joint AND manipulation 76 citations


Combining more than 2 terms

sacroiliac joint AND manipulation AND chiropractic18 citations

sacroiliac manipulation joint

chiropractic


Boolean operator OR

• OR expands a search– All articles that contain either of the queried

terms are retrieved

• For example– Searching PubMed for sacroiliac joint OR

manipulation expands the results to 36,503

• OR is useful when searching for different versions of a word – e.g., manipulation OR adjustment


OR example

sacroiliac joint 2,760 citations

manipulation 33,819 citations

sacroiliac joint OR manipulation

36,503 citations


Boolean operator NOT

• NOT also limits or narrows down a search– Only retrieves citations that do include the first

term, but do not include the second term

• For example– Searching PubMed for sacroiliac joint NOT

manipulation narrows down the number of citations from 2,760 to 2,684

– 76 articles include manipulation and the SI joint, so they are eliminated


NOT example

sacroiliac manipulation joint

sacroiliac joint

NOT

manipulation

Articles that include both sacroiliac joint and manipulation are eliminated


Nesting

• Controls the order in which PubMed processes search terms– From left to right by default

• Search terms are enclosed in parentheses – Terms within the parentheses are processed

first – Boolean operators can be included


Nesting example

• If a doctor wants information on the non-surgical treatment of carpal tunnel syndrome, the query might look like this – carpal tunnel syndrome AND (treatment NOT

surgery)

• This search will locate articles that deal with treatment, but not those that involve surgery


Nesting example 2

• Searching chiropractic AND (whiplash OR chronic pain)

• The database will first find all references that contain whiplash plus those that contain chronic pain

• Then it will restrict results to those that also contain the word chiropractic


The AND operator is used between words by default

• PubMed searches for headache AND therapy exactly the same way as headache therapy – Thus, AND is sometimes optional

• To see how PubMed performed a search– Click the Details tab after the search is

complete– Read the Query Translation


Details tabDetails tab

Translation is exactly the same

when AND is used

Translation is exactly the same

when AND is used


Query Translation

• Useful in figuring out why an unproductive search failed

• Also to plan a subsequent search strategy that will be more successful


Automatic Term Mapping

• When terms are searched without a field tag, they are matched (in order) against the – MeSH Translation Table– Journals Translation Table– Full Author Translation Table– Author Index


Automatic Term Mapping (cont.)

• If the term matches a MeSH term, it is searched both as a MeSH term and a Text Word

• The Journals Translation Table yields an abbreviated title when the journal’s full title is searched – Journal of the American Medical Association– JAMA or J Am Med Assoc


Automatic Term Mapping (cont.)

• The Full Author Translation Table retrieves the author’s full name– Only for articles published after 2001

• Order of names doesn’t matter– Searching meeker william c is equivalent to

william c meeker

• Commas are not necessary – Helpful to distinguish first from last names

(e.g., John James)


Truncation (a.k.a, wildcard search)

• Search for various uses of the same root word – The root word verte can be expanded to

vertebra, vertebrae, vertebral, etc.– Searching only vertebral misses other forms

of the word

• The root word with an asterisk retrieves all forms of the word– e.g., verte*


Truncation (cont.)

• An * can be placed at the beginning or end of search terms

• An * can also be placed within a word when a letter is variable or absent – The search term an*emia will look for anemia

and anaemia – analy*e will look for analyze and analyse


Phrase searching

• Forces PubMed to search for a phrase rather than individual terms

• Only the exact phrase will be queried• The phrase must be place within quotation

marks – A search of intervertebral disc herniation

produces 11,747 citations– Whereas “intervertebral disc herniation”

produces only 183


Medical Subject Headings (MeSH)

• A list of vocabulary terms used to index medical literature – Developed by the National Library of Medicine

(NLM)

• MeSH terms are assigned to all MEDLINE records by NLM indexers corresponding to the article’s major topics


Finding MeSH terms

• Select MeSH from the drop-down list next to the Search button on the PubMed homepage

• Enter term in PubMed query box

• A list of the MeSH terms or alternative suggestions will appear


Select MeSHSelect MeSH Enter termEnter term


No terms foundNo terms found

Suggested termsSuggested termsClick likely termsClick likely terms


List of MeSH terms (only one in this case)

List of MeSH terms (only one in this case)


Finding MeSH terms (cont.)

• Another way to find MeSH terms is to view the citation format of an article– Click Citation from the drop-down list next to

the Display button located at the top and bottom of each page of retrieved records


Check the articles of interest

Check the articles of interest

Select CitationSelect Citation


The complete citation appears

The complete citation appears

Including a list of MeSH terms

Including a list of MeSH terms


Finding MeSH terms (cont.)

• A final way to find MeSH terms is to perform a free-text search then look at PubMed’s automatic term mapping translation– Click the Details tab and look at the terms in

the Query Translation box– MeSH terms have a [MeSH Terms] field tag

next to them


Building a MeSH search

• From the MeSH database– Select terms to include in the search by

checking the adjacent box– Select the location to send the term to in the

Send to drop down list– Other MeSH terms can be found and added to

the Search Box by repeating this process


Check MeSH termCheck MeSH term

Send term to Search Box with AND, OR, or NOT

Send term to Search Box with AND, OR, or NOT


More terms can be added to build a search

More terms can be added to build a search

Click when ready to perform the search

Click when ready to perform the search


MeSH (cont.)

• MeSH indexers must– Have at least a bachelor's degree in a

biomedical science – Have reading knowledge of one or more

foreign languages – Be trained in principles of MEDLINE indexing

and complete several weeks of on-the-job training at the Library

• MeSH terms may at times be incorrect


MeSH terms are optional

• Search using any word in the title, abstract, or other field of the citation

• However, searching with MeSH terms narrows down the search and provides more focused results

• MeSH terms should be used when possible


MANTIS - Controlled Supplemental Vocabulary

• Similar to MeSH headings– Functions with MeSH terms– Search terms are specific to complementary

and alternative medicine – e.g., Gonstead Technic, Toggle Recoil

Adjustment, Innate Intelligence, etc.

© 2006 1 literature searching a literature search identifies relevant information sources that are...

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