researchquestionsDelvaux

14/10/2015
How to search for evidence
and literature based upon a
well formulated research
question
Nicolas Delvaux, 15/10/2015
How to start a literature review
• Formulate a research question
• Start a systematic literature search
choose relevant databases
translate research question into search concepts
• Appraise the evidence
• Evaluate the results
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Formulating research questions
• PICO(S) format
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P(opulation): describes demographics or specifics of population
I(ntervention): describes the intervention, treatment, exposure
C(omparator): describes the comparison, placebo, golden standard
O(utcome): describes outcome parameters
S(tudy design): describes the type of study
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Formulating research questions
• Effectiveness: among individuals with a certain disease or condition (P), how
effective is a certain treatment or approach (I) in producing an outcome or
benefit (O)?
• Intervention harms: Among individuals with a certain disease or condition (P),
what are the unintended consequences (harms, O) of a certain treatment or
approach (I)?
Formulating research questions
• Diagnosis: Among patients with a certain condition (P), how accurate is a
certain test (I) in diagnosing a given disease (O) compared with a golden
standard (C)?
• Values and preference: What are the values and preferences (O) of individuals
with a certain disease or condition (P) in terms of the potential outcomes of the
intervention or exposure being considered(I)?
Formulating research questions
• Risk or prognosis: Among patients with a certain disease (P), does a prognosis
or risk factor (I), change the risk of a certain event (O) relative to baseline risk
(C)?
• Resource considerations: What is the cost of intervention X in setting Y? What
is the cost-effectiveness of intervention X in setting Y, for outcome Z?
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Features of research questions
• Broad research questions
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pros: comprehensive evidence summary, generalizable findings, large body
of evidence
cons: heterogeneous evidence, difficult interpretation
• Narrow research questions
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pros: easier to manage
cons: sparse evidence, findings less generalizable
Starting a systematic literature search
• What am I looking for?
• Where do I look for it?
• How do I look for it?
Starting a systematic literature search
• 6S model of quality of
preappraised literature
• start higher up the pyramid and
work your way down
DiCenso A, Bayley L, Haynes RB. Accessing preappraised evidence: fine-tuning the 5S
model into a 6S model. Ann Intern Med. 2009;151:JC3-2. doi:10.7326/0003-4819-151-6200909150-02002
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Starting a systematic literature search
Quaternary sources:
guidelines, evidence summaries
Tertiary sources:
Clinical Evidence, DARE
Secondary sources:
systematic reviews and meta-analyses, independent reviews
Primary sources:
original studies, Pubmed
Waterfall approach. Degryse, 1997
Starting a systematic literature search
Quality research
design
Centre of evidence-based medicine, www.cebm.net
Starting a systematic literature search
• What am I looking for?
• Where do I look for it?
• How do I look for it?
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Summaries
• Clinical summaries
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clinical pathways or textbook summaries
include evidence-based information
provide regular updating
• Databases
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Dynamed: www.ebscohost.com/dynamed/default.php
Clinical Evidence: www.clinicalevidence.com
(UpToDate: www.uptodate.com)
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Summaries
• Includes clinical practice guidelines (CPGs)
“systematically developed statements to assist practicioner and patient
decisions about appropriate health care for specific clinical circumstances”
o based on comprehensive searches and appraisal of the literature
o recommendations should have level of evidence
• Databases
o Guidelines International Network (www.g-i-n.net)
o National Guidelines Clearinghouse (www.guidelines.gov)
o EBMPracticeNet (www.ebmpracticenet.be)
• Cave
o not all guidelines are equally trustworthy!
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Synopses of syntheses
• Syntheses = systematic review = comprehensive summary of all research
related to a focussed clinical question
o quantitative summary: meta-analysis
o non-quantitative summary: narrative
• Synopsis that summarizes findings of high-quality SR
• Databases (Evidence based abstraction journals)
o ACP Journal Club (www.acpjc.org)
o Evidence-Based Medicine (http://ebm.bmj.com)
o Evidence-Based Mental Health (http://ebmh.bmj.com)
o Evidence-Based Nursing (http://ebn.bmj.com)
o Database of Abstracts of Reviews of Effects (DARE)
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Syntheses
• Databases of systematic reviews
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ACPJC PLUS (http://plus.mcmaster.ca/acpjc)
EvidenceUpdates (http://plus.mcmaster.ca/evidenceupdates)
Nursing+ (http://plus.mcmaster.ca)
Cochrane Library (www.thecochranelibrary.com)
Campbell Library (www.campbellcollaboration.org/library.php)
Epistemonikos (www.epistemonikos.org)
TRIP database (www.tripdatabase.com)
SUMSearch (http://sumsearch.uthscsa.edu)
Syntheses
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Starting a systematic literature search
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Synopses of single studies
• Provides summarized, but sufficiently detailed summary of high quality study
• Databases:
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Evidence-based abstraction journals
Minerva (www.minerva-ebm.be) Dutch
Single original study
• Databases for primary research
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depends on the focus of the research
depends on the search engine
• Databases
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General: MEDLINE, Embase, Cochrane Library
Specific professions: CINAHL, PEDro, PsycINFO, AMED, INSPEC, ...
Specific interests: Medion, Cochrane Central Register of Controlled Trials,
clinicaltrials.gov, ...
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Single original study
• Search engines
Starting a systematic literature search
• What am I looking for?
• Where do I look for it?
• How do I look for it?
Navigating from a research question to search terms
• Research question
o
What is the effectiveness of acetylsalicylic acid for preventing cardiovascular
death in patients with coronary heart disease?
• Define the different concepts
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P: patients with coronary heart disease
I: aspirin
C: unspecified
O: cardiovascular death
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Navigating from a research question to search terms
• Concept “Coronary heart disease”
• Find synonyms defining concept “coronary heart disease”
• Each database may use different synonyms!
• Start with Mesh
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Major Subject Headings
classification of synonyms in branched structure
includes more than one synonym
Search for Mesh terms using Pubmed browser
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Navigating from a research question to search terms
• Filters for study design
• Some search engines have built in filters for study design
• Use predefined (and validated) search terms for study designs
http://clinicalevidence.bmj.com/x/set/static/ebm/learn/665076.html
Chapter 6.4.11 Cochrane Handbook for Systematic Reviews of Interventions
o https://sites.google.com/a/york.ac.uk/issg-search-filtersresource/home/search-filters-by-design
o http://www.sign.ac.uk/methodology/filters.html
• Be careful when using search filters! Are they validated? For Ovid or for
Pubmed?
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Navigating from a research question to search terms
• Use Boolean logic to combine concepts
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Navigating from a research question to search terms
Languages
• Most databases work with English search terms
• Translating terms not always easy
• Facilitators
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Google: try various terms and compare amount of hits
Eurodicautum dictionary IATE
• InterActive Terminology for Europe
• http://iate.europa.eu/
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Multilingual Glossary of technical and popular medical terms in nine
European Laguages
• http://users.ugent.be/~rvdstich/eugloss/welcome.html
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