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School of Medicine, Year 1 & 2: Research Elective

Has a systematic review on my research question already been done?

Are you considering taking on a systematic review?  Before deciding, it is prudent to see If a systematic review of your topic has already been conducted.  You can search databases for published systematic reviews and registries for systematic review protocols. For example:

Systematic Reviews:

  • PubMed (filter to systematic reviews)
  • Cochrane Database of Systematic Reviews

Protocol Registries:

  • PROSPERO
  • Cochrane Database of Systematic Reviews
  • PubMed
  • Joanna Briggs Institute Systematic Review Register

What databases do I search?

That all depends on your research question.  In the health sciences, MEDLINE (available through PubMed), Embase, and Scopus are top recommendations.  However, you have access to dozens of bibliographic databases; your selection will depend on your topic.  These databases are primarily composed of journal articles.  If you are including other content types, like gray literature, you will need to search other sources as well. 

UR so basic. What's the difference between basic, advanced, and expert searching?

Start with a written plan for searching the databases. For systematic reviews, an advanced or expert search strategy should be used.  Each database has a specialized vocabulary and syntax.

PubMed:

  • Controlled vocabulary is MeSH
  • Use FAQs and PubMed tutorials for details on advanced and expert searching
  • PubMed advanced searching tips (Johns Hopkins University)

Embase:

  • Controlled vocabulary is Embase
  • Use FAQs and Embase tutorials for details on advanced and expert searching
  • Embase advanced searching tips (Johns Hopkins University)

Steps in Literature Search Process

PICO METHOD

The PICO method is a way to form specific clinical questions and to formulate a database search strategy.  The PICO mnemonic helps you to identify the key concepts that need to be in articles in order to answer your clinical question.  
P: Population, Patient, or Problem
How would you describe a group of patients similar to yours? What are the most important characteristics of the patient? What is the condition or disease you are interested in?
I: Intervention, Prognostic Factor, Exposure
What main intervention or exposure you are considering? What do you want to do with the patient? What is the main alternative being considered?
C: Comparison
What is the main alternative to compare with the intervention? Are you trying to decide between two drugs, etc.? It can be none or placebo.
O: Outcome
What are you trying to accomplish, measure, or affect? Can be disease-centered or patient-centered?
T: Time*
How much time does it take to demonstrate the clinical outcome? How long does it take for an intervention to achieve its outcome? How long are participants observed?
 *Not every question will have a time component.

Forming a Clinical Question

After using PICO you will have all the elements necessary to formulate a specific, relevant clinical question.  Questions will include all the elements of PICO that you pulled from the clinical scenario.  Everyone will "see" a different way to write out the clinical question.  Below is a formula you can use to build clinical questions using PICO until you get comfortable. 
In _________ (P), what is the effect of ___________ (I) compared to ______________ (C) on ______________(O) over _______ (T)*
*Remember that Time is not always necessary, often it is conveyed or understood from the question.

Credit: Lauren Fletcher, Rowland Medical Library

Selecting keywords & index terms are one of the most important parts of the research process.  Databases don't think like Google - they don't understand sentences or questions - they understand words.  By picking out the best terms you are telling the database what you need it to search.  

Keywords

Keywords: The terms the author uses within the article & abstract. 
When selecting keywords - determine what YOU think are the most important words in your research questions.  What should the database care about? 
The easiest way to determine keywords is to select the most important nouns.

 

After selecting your keywords, it is important to think of synonyms or alternative ways to say your keywords.  Not all authors talk about or spell concepts the same way.  It's important to think through all the different ways an author or database might say a keyword to find all the relevant sources.  
Think through the following ideas to help you find additional related terms:
  • American vs British spelling
  • Different word endings like singular vs plural
  • Different words for the same concept (eg teens, adolescents, youths)
  • Include both the acronym and the full term
EXAMPLE
Concept 
Teenager
Heart Attack
Advertisements
Related Terms 
Adolescent
Young Adult
Myocardial Infarction
Cardiovascular Stroke
marketing
commercials 
Selecting keywords & index terms are one of the most important parts of the research process.  Databases don't think like Google - they don't understand sentences or questions - they understand words.  By picking out the best terms you are telling the database what you need it to search.  

Index Terms

Index Terms: Specific terms assigned to an article or predetermined by an "indexer" to allow for more focused searching. 
When searching index terms - use the keywords you previously selected.  
Read through the term description to ensure you are searching the right concept.

Common Databases with Index Terms

MeSH (Medical Subject Headings): Index term for PubMed/MedLine and the National Library of Medicine. 
Emtree: Index Term for EMBASE.
CINAHL Subject Headings: Index Term for CINAHL.
Thesaurus: Index Terms for PsychINFO/PsychARTICLES
 
EXAMPLE
Term
Teenager
Heat Attack
MeSH
"Adolescent"[Mesh]
"Myocardial Infarction"[Mesh]
Emtree
'adolescent'/exp
'heart infarction'/exp
CINAHL Headings
(MH: "Adolescence")
(MH "Myocardial Infarction")

 

Create your search by combining your keywords & index terms using Boolean Operators - AND, OR, NOT
AND is used to narrow your search.  Results will contain both concepts.
OR is used to expand your search.  Results will return either term.
NOT will limit your search.  Results will exclude a keyword.

Use parenthesis to combine all your search terms with Boolean to create search strings.  These are what the database will use to search.
OR should go between synonyms
AND should combine groups of synonyms.
Search strings using PICO usually look like:
(P OR P OR P) AND (I OR I OR I) AND (C OR C OR C) AND (O OR O OR O)

 
**Princess George Community College, 2015
 
Search FIlters
Particular search strategies that have been developed to define certain criteria for your search.  Many databases have built-in search filters. 
Common Filters:
  • Age
  • Publication Type
  • Study Type
  • Species
  • Language
  • Sex
Be cautious with search filters.  These can exclude newer or relevant studies from your search.  
For more information using search filters, contact Lauren Fletcher or visit the Systematic Review: About Search Filters Guide from Dalhousie University.
The final step in the searching process is to review your search strategy and revise. 
  • Double-check your search string:
    • Are you using Boolean Operators correctly?
    • Have you left out any relevant terms?
  • Review your results:
    • Are the right types of articles in your results?
    • Are your keywords or index terms displaying in the title, abstract, or text?
  • Review your filters:
    • Are your filters narrowing the results too much?
  • Revise your search strategy
    • Your search strategy is supposed to improve and evolve.
Remember, not all databases think alike.  You might have to change out keywords & index terms depending on the database you are using

Where can I learn more?

Ma, LL., Wang, YY., Yang, ZH. et al. Methodological quality (risk of bias) assessment tools for primary and secondary medical studies: what are they and which is better?Military Med Res 7, 7 (2020). https://doi.org/10.1186/s40779-020-00238-8