Exhaustive Literature Searching (Systematic Reviews)

CONSTRUCTING AND

REPORTING EXTENSIVE

LITERATURE SEARCHES

Mark MacEachern, MLIS

Overview

Search construction

Sources

PubMed, OVID MEDLINE, EMBASE, etc.

Reporting

From: Users’ Guide to the Medical Literature

(JAMA Evidence)

Evidence Pyramid

Why search?

A high-quality lit search is essential for a successful

meta-analysis

It is from the search results that data is gathered for

analysis

Failure to locate important studies can significantly affect

results

Remember the goal is to capture every relevant study

Important to report search so your methodology can be

reproduced

What to expect?

Expect 1000s of results

Expect to search multiple databases

Ovid, EMBASE, PubMed, Scopus, etc.

Expect the search process to take awhile

Expect to publish search strategy and search

methodology

Expect to consult a professional with search expertise

(health sciences librarian)

Search construction

Concept building

Boolean logic

Vocabulary

Techniques

Evaluating searches

Search construction: Concept

building

Identify major concepts of topic

PICO helps for clinical questions, but the concept can be applied in other contexts

Example: Do any olfactory identification tests predict the development of Alzheimer’s disease? ] http://www.ncbi.nlm.nih.gov/pubmed/22552846

What are the major concepts? Alzheimer disease

Olfactory tests

Predict?

People/Humans?

http://www.ncbi.nlm.nih.gov/pubmed/22552846

Search construction: Concept

building

Alternate words / Synonyms

Alzheimer, Alzheimer’s, dementia, cognition

disorders

Olfactory tests, sniffin’ sticks, b-sit, cc sit, smell

identification test

Search construction: Boolean

Logic

ANDAlzheimer’

s DiseaseOlfactory

test

DementiaAlzheimer’

s disease

AnimalsHumans

OR

NOT

Concept 2

Search construction: Boolean

Logic

Concept 1

Alzheimer

disease

dementia

ANDOR

OR

OR

OR

(alzheimer disease OR dementia) AND (olfactory identification test OR b-sit OR sniffin’

sticks OR …)

Olfactory

Identification test

B-sit

Sniffin’ Sticks

Etc.

Search construction:

Vocabulary

Keywords

Controlled

vocabularies


Vocabulary

Keywords

Controlled

vocabularies

What are they?

Literal search

Looks for occurrences of words

When to use?

Current topics

Not easy to describe concepts

No vocabulary exists in database

Examples

Drug names (Lipitor, Prozac)

Slang

Concepts (Swine flu, oil spill)


Vocabulary

Keywords

Controlled

vocabularies

What are they?

Set of words or phrases used to

describe concepts

Dictionary of accepted terms for a

database

When to use?

Searching a database that uses one

Examples

MeSH (Medical Subject Headings)

EMTREE (Embase)


Vocabulary

Keywords

Controlled

vocabularies

MeS

H


Techniques

Truncation

Wild cards

Adjacency

Phrases

Boolean

Parentheses

residen*

an?sthesiology, p?diatrics

screen* adj5 cancer*

“dental education”

“dental implants”[mh] AND “dental

restoration failure”[mh]

(“dental implants”[mh] OR

implants[title/abstract]) AND (“dental

restoration failure”[mh] OR

failure[title])

Note: Techniques vary from database to database


Techniques

Limits or Filters – use sparingly (language, species, pt)


Techniques

Exploding subject headings

Databases handle explosion differently


Techniques

Subheadings

“dental implants/standards”[mesh]


Techniques

Floating subheadings

1. exp Arthritis, Rheumatoid/

2. exp Inflammatory Bowel

Diseases/

3. cuc.tw.

4. chronic ulcerative colitis.tw.

5. crohn*.tw.

6. ibd.tw.

7. rheumatoid arthritis.tw.

8. or/1-7

9. exp Postoperative

Complications/

10. exp Perioperative Care/

11. su.fs.

12. or/9-11

13. 8 and 12

Ovid MEDLINE (extract)

("inflammatory bowel diseases"[mh] OR

"chronic ulcerative colitis”[tiab] OR cuc[tiab]

OR crohn[tiab] OR "crohn's” [tiab] OR

crohns[tiab] OR ibd[tiab] OR "rheumatoid

arthritis” [tiab]) AND ("postoperative

complications"[mh] OR "perioperative

care"[mh] OR "surgery”[subheading] OR

"post operative"[tiab] OR

"postoperative"[tiab])

PubMed (extract)

Search construction: Filters

A predefined search designed to target specific study methodologies (RCTs, Cohort, Systematic Reviews)

Use a validated filter (whenever possible)

Example: PubMed Clinical Queries – Systematic Reviews

(systematic review [ti] OR meta-analysis [pt] OR meta-analysis [ti] OR systematic literature review [ti] OR (systematic review [tiab] AND review [pt]) OR consensus development conference [pt] OR practice guideline [pt] OR cochrane database syst rev [ta] OR acp journal club [ta] OR health technol assess [ta] OR evid rep technol assess summ [ta] OR drug class reviews [ti]) OR (clinical guideline [tw] AND management [tw]) OR ((evidence based[ti] OR evidence-based medicine [mh] OR best practice* [ti] OR evidence synthesis [tiab]) AND (review [pt] OR diseases category[mh] OR behavior and behavior mechanisms [mh] OR therapeutics [mh] OR evaluation studies[pt] OR validation studies[pt] OR guideline [pt] OR pmcbook)) OR ((systematic [tw] OR systematically [tw] OR critical [tiab] OR (study selection [tw]) OR (predetermined [tw] OR inclusion [tw] AND criteri* [tw]) OR exclusion criteri* [tw] OR main outcome measures [tw] OR standard of care [tw] OR standards of care [tw]) AND (survey [tiab] OR surveys [tiab] OR overview* [tw] OR review [tiab] OR reviews [tiab] OR search* [tw] OR handsearch [tw] OR analysis [ti] OR critique [tiab] OR appraisal [tw] OR (reduction [tw]AND (risk [mh] OR risk [tw]) AND (death OR recurrence))) AND (literature [tiab] OR articles [tiab] OR publications [tiab] OR publication [tiab] OR bibliography [tiab] OR bibliographies [tiab] OR published [tiab] OR unpublished [tw] OR citation [tw] OR citations [tw] OR database [tiab] OR internet [tiab] OR textbooks [tiab] OR references [tw] OR scales [tw] OR papers [tw] OR datasets [tw] OR trials [tiab] OR meta-analy* [tw] OR (clinical [tiab] AND studies [tiab]) OR treatment outcome [mh] OR treatment outcome [tw] OR pmcbook)) NOT (letter [pt] OR newspaper article [pt] OR comment [pt])http://www.nlm.nih.gov/bsd/pubmed_subsets/sysreviews_strategy.html

Search construction: Methodologic

Filters

From PubMed Clinical Queries

Search construction: Methodologic

Filters

Sources

PubMed

Ovid MEDLINE

EMBASE

Scopus

Web of Science

PsycINFO

CINAHL

Cochrane Database of

Systematic Reviews

Conference Papers

Index

ClinicalTrials.gov

ERIC

Proquest Theses &

Dissertations

CABI

Google Scholar

Sociological Abstracts

And others…

Sources: PubMed

(pubmed.gov)

Primary biomedical

database

22+ million citations

Native interface for

MEDLINE dataset

Citations indexed with

MeSH

Sources: PubMed

Sources: Ovid MEDLINE

Different interface to search MEDLINE dataset

Heavily used for systematic reviews

Provides additional

search functionality

(adjacency)

Uses MeSH (like

PubMed)



Sources: EMBASE

Similar to PubMed, Ovid

Indexes man more international journals

Drug indexing is a plus

Uses EMTREE

Includes MEDLINE,

unless you NOT out

Sources: Web of Science

Citation database

Times cited & conference

proceedings

Other ISI databases:

Impact Factors

Biosis Previews

Sources: Other options

Examine the references of articles of relevance

Included studies and relevant reviews

Use cited by features

Set up email alerts

Contact authors, companies, organizations,

societies, etc

Search for ongoing studies (prelim data)

Hand search important journals (by Impact Factor,

perhaps)

Citation tracking

Reporting

Reporting

See PRISMA statement

“The aim of the PRISMA Statement is to help authors

report a wide array of systematic reviews to assess the

benefits and harms of a health care intervention. PRISMA

focuses on ways in which authors can ensure the

transparent and complete reporting of systematic reviews

and meta-analyses.”

http://www.prisma-statement.org/statement.htm

Reporting

See Cochrane Handbook

http://www.cochrane-handbook.org/

Section 6.6

“It should be borne in mind at the outset that the full

search strategies for each database will need to be

included in an Appendix of the review.”


Reporting



Section 6.6

In study flow diagram:

number of unique records identified by the searches;

number of records excluded after preliminary screening (e.g. of titles

and abstracts); and

number of records retrieved in full text


Reporting



Section 6.6

In abstract:

List all databases searched.

Note the dates of the last search for each database or the period

searched.

Note any language or publication status restrictions (but refer to Section

6.4.9).

List individuals or organizations contacted.”


http://www.mrc-bsu.cam.ac.uk/cochrane/handbook/chapter_6/6_4_9_language_date_and_document_format_restrictions.htm

Reporting



Section 6.6

In methods:

List all databases searched.

Note the dates of the last search for each database AND the period

searched.

Note any language or publication status restrictions

List grey literature sources.

List individuals or organizations contacted.

List any journals and conference proceedings specifically handsearched

for the review.

List any other sources searched (e.g. reference lists, the internet).


Reporting

Example

Recap

Spend time developing your search

Search multiple databases

Take notes during process

Give thought to how you want to report on the data

collection

Consult an expert searcher

Thanks!

Mark MacEachern, MLIS

Informationist, Taubman Health Sciences Library

[email protected]