Advanced Medline

Franklin Sayre

franklin.sayre@ubc.ca

Objectives

By the end of this session you should be able to:

1. Use MeSH scope notes to better focus your searching2. Determine when to use explode, focus, and subheadings 3. Determine when to use keywords4. Use some advanced keyword search operators

Medline: Content & Scope

• Produced by the U.S. National Library of Medicine (NLM)• 1946 to present • ~20 million records• US Based, 95% english• Citations from approximately 5,600 worldwide journals in 39

languages (careful review of journals for selection)• 2,000-4,000 records added per day

Medline: Pubmed vs. Medline

Pubmed

MEDLINE (searchable in Pubmed, OvidSP,

EBSCO, etc.)

• Some in-process citations

• Some older material

• Some eBooks

• Medline is a database• Pubmed is an interface

to Medline that includes some other material

• Medline can be searched using different interfaces (OvidSP, EBSCO)

*98% of what pubmed searches is searchable from other interfaces.

Medline is a database searchable through different interfaces

Review: Medline - Organization

Medline contains bibliographic records not the full text of articles:

• A bibliographic record contains:

• Title

• Authors

• Abstract

• MeSH Headings

• Other descriptive information

• Example Record: Mortality in relation to smoking: 50 years' observations on male British doctors: http://www.ncbi.nlm.nih.gov/pubmed/15213107

Medical Subject Headings (MeSH)

MeSH are a system of Subject Headings (also called a “Controlled Vocabulary”):

• Subject Headings are a system that designates a single authorized term or phrase for each unique concept

• Helps control for variations in human language such as synonyms, spelling, and alternative phrasings

• Similar to ICD9/10 Codes and other classification systems• Assigned to articles by indexers who apply the most

appropriate headings to describe the content of the article

Medical Subject Headings(MeSH): Examples

Two example MeSH:•Pregnancy: http://www.ncbi.nlm.nih.gov/mesh/68011247•Pregnant Women: http://www.ncbi.nlm.nih.gov/mesh/68037841

Example Record with MeSH: •Mortality in relation to smoking: 50 years' observations on male British doctors: http://www.ncbi.nlm.nih.gov/pubmed/15213107•See the MeSH headings applied to this article and how they describe various characteristics of the article

Medical Subject Headings (MeSH): Scope Notes

Parts of a Scope Note:

PREFERED TERM: The official term for that disease, process, etc. as assigned by NLMDEFINITION: The scope of the definition; what this MeSH covers.YEAR INTRODUCED: Important because articles indexed before this year will not be searchable using this MeSH.PREVIOUS INDEXING: The MeSH used to index this concept before the term was created.AVAILABLE SUBHEADINGS: Subheadings that can be appliedENTRY TERMS: Other terms for this concept (useful for building lists of keywords)SEE ALSO: Related MeSH termsMeSH TREE: Location within MeSH Tree

Activity: Understanding MeSH Scope Notes (5 minutes)

• Search for a few different kinds of concepts, e.g. • A disease or condition• Something that causes a disease or condition• A therapy/test/intervention• An outcome• A social/cultural concept, group, geographic area

• Record the name of the MeSH and anything interesting about the definition, year introduced, related terms, and available subheadings (don’t worry about writing everything down)

Activity: Understand MeSH Scope Notes (Wrap-up & Discussion)

Did you notice anything interesting?

•Definition: Notice how specific the definition is?•Year Introduced: Why then? How would this effect searching?•Previous Indexing: What would you need to do to find older material?•Way that MeSH split concepts up: E.G. Definition? Related Terms? Previous Indexing?•Available Subheadings: How do they compare with the subheadings available for other kinds of concepts?

Searching with MeSH: Three Questions

Explode, focus, subheadings

1. Should I explode?2. Should I focus?3. Should I use subheadings?

Searching with MeSH: Do I want to explode?

Explode includes all narrower headings in the MeSH tree

• MeSH headings are organized in a hierarchy from broad to narrow concepts

• Articles are indexed to the narrowest (most specific) level possible

• Example: Canada (http://www.ncbi.nlm.nih.gov/mesh/68002170)• If an article is about Canada generally it will be indexed with

“Canada”• If it is specifically about British Columbia it will be indexed

with “British Columbia” but NOT with “Canada”• Explode includes all narrower concepts bellow that heading in

the MeSH tree in your search

Medical Subject Headings (MeSH): Tree

A. Anatomic termsB. OrganismsC. DiseasesD. Drugs and chemicalsE. Analytical,Diagnostic&Therapeutic Techniques & equipment F. Psychiatry and Psychology G. Phenomena & Processes H. Disciplines & Occupations I. Anthropology,Education,Sociology and Social Phenomena G. Technology,Industry,Agriculture K. HumanitiesL. Information Science Named Groups N. Health Care M.Publication Characteristics P. Geographicals

Activity: Exploding vs. Not Exploding (5 minutes)

Take one or more of the MeSH headings you found earlier:

1.Find where it is located in the MeSH tree2.See if it has any narrower headings under it, if it doesn’t use another heading that does3.Run a search with just the heading (not exploded)4.Run a second search where you explode the heading5.Notice the difference in search results

NOTE: For now ignore both focus and subheadings

Searching with MeSH: Do I Want to Focus?

Focus designates the MeSH that are the main intellectual “focus” of the article

• Focus is given to 2-4 MeSH that reflect the main “focus” of an article, i.e. the concepts that the article is primarily about

• Example: Mortality in relation to smoking: 50 years' observations on male British doctors (http://www.ncbi.nlm.nih.gov/pubmed/15213107) Focus was given to:

• Neoplasms/mortality*• Physicians/statistics & numerical data*• Smoking/mortality*• Smoking Cessation/statistics & numerical data*

• When you use “focus” you’re saying you only want to see articles where the concept that MeSH designates is a main focus of the article.

• Should not be used with systematic reviews or if you need to be comprehensive.

Activity: Using Focus (5 minutes)

Take one or more of the MeSH Headings you searched for earlier:

1.Search for it again and this time select the focus option2.Run the search and compare how many results you received with the number you returned when you didn’t use focus3.Scan through a few of the results and note how their content more closely centres around that concept.

NOTE: For now ignore subheadings

Searching with MeSH: Do I want to use Subheadings?

Subheadings limit your search to particular aspects of a concept

• Subheadings get at particular aspects of a MeSH heading• Also called qualifiers• Example Record: Mortality in relation to smoking:

• Neoplasms/mortality• Smoking Cessation/statistics & numerical data

• 88 in total, including: Diagnosis, Drug Therapy, Drug Effects, Economics, Psychology, Rehabilitation, Trends, etc.

• Specific subheadings are only available if relevant to that MeSH heading (not every subheading is applicable for every MeSH heading)

Activity: Using Subheadings (5 minutes)

Take a MeSH you searched for earlier:

1.Search for it again, this time when you get to the subheadings screen select one of the subheadings2.Look at the results and see how they differ from the results you found earlier in number and content3.Search for a different kind of heading (e.g. if you already searched for a diseases try searching for a drug or social group) and note the different subheadings that are available

NOTE: For now ignore subheadings

Keywords

• Keywords are words used in the title and abstract of the article (and a number of other fields)

• Based on simple character matching• Things to think about:

• Language used by authors in your field • Synonyms• Alternative spellings (including British spellings)• Plural and other word root endings• Alternative phrasing• Abbreviations• etc.

MeSH vs. Keywords

MeSH Keywords

• Established concepts (Diabetes, Heart Disease)

• Core biomedical concepts (diseases, drugs & chemicals, anatomy)

• Traditional parts of medicine (Surgery, Immunology)

• Newer concepts (eHealth)• Boundary-crossing topics

(psychosocial and humanities concepts)

• New parts of medicine (Rehabilitative Sciences, Population and Public Health, etc.)

• New Articles (not yet indexed)• Errors in indexing

Often you need to use a combination of MeSH and keywords

Indexing Status and MeSH vs. KeywordsThe delay in indexing articles means newer material can only be found using keywords

Status What it Means Search using MeSH?

PubMed - as supplied by publisher

Citations recently added to PubMed via electronic submission from a publisher, and are soon to proceed to the next stage, PubMed - in process

No

PubMed - in process

Citations bibliographic data will be reviewed and indexed, i.e., MeSH terms will be assigned (if the subject of the article is within the scope of MEDLINE).

No

PubMed - indexed for MEDLINE

Citations that have been indexed with MeSH terms, Publication Types, Substance Names, etc., and bibliographic data have been reviewed.

Yes

Tools for Keywords

Phrases: Find a specific phrase (more specific)•“cultural deprivation”

Proximity: Find words within a X words of each other (more flexible, increases the number of results)•needle ADJ2 exchange•Proximity searching is not available in every interface, see help

Truncation: Find alternative word endings (increases results)$ OR * in OvidSP databases will search for multiple word endings•needle* – will search for needle or needles etc

Wildcards: Find alternative spellings (more flexible, inceases results)•Colo*r

Activity: Search using keywords (10 minutes)

1. Try searching using:

1. An individual word (e.g. education)

2. A phrase (e.g. “medical education”)

3. Truncation (educat*)

4. Proximity searching (e.g. medical ADJ3 education)

Limits

Aspects of Study Design and Publication Type

• Always apply limits last • Limits are not necessarily perfectly applied and their

application may not always be consistent. When doing systematic reviews speak to a librarian about using filters instead

Activity: Applying Limits (5 minutes)

1. Try the following limits:

1. Publication Year

2. Age Groups (age of study population)

3. Publication Types

1. Randomized Controlled Trial

2. Review

3. Systematic Review

4. Comparative Study

Activity: Survey (3 minutes)

Your feedback helps us improve our current workshops and plan services based on your needs. Please take a moment to fill out the survey and give us your feedback.