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HLTD08: Implementation Science in Global Health

Fall 2020 (HLTD04) & Winter 2021 (HLTD08) - Professor Ezezika

Identify Main Concepts

Start the search process by identifying the major concepts in your topic or research question. Think of these as the most important aspects of the topic. They are usually the nouns in your research question, such as people or populations, issues, or places. 

In the health sciences, you can use the PICO Framework to identify the main concepts in a clinical question:  

PICO Framework Item Example
P Patient, problem, or population
  • Disease or health condition
  • Patient's demographics
  • Patient's risk factors
I Intervention
  • Exposure
  • Therapeutic measure (e.g. medication, surgical intervention, lifestyle change)
  • Preventative measure
  • Diagnostic test or procedure
C Comparison or control (optional)
  • Standard care
  • Different intervention or preventative measure
  • Placebo
O Outcome
  • Effect(s) or side effect(s) of the intervention or exposure
  • Measure of clinical wellbeing or quality of life (e.g. disease incidence, mortality rate, survival rate, rate of disease progression)

Example

Research question: What are the barriers and facilitators of the adoption of malaria bednets in Sub-Saharan Africa?

Main concepts: malaria in Sub-Saharan Africa (problem & population), bednets (intervention), adoption of bednets - barriers and facilitators (outcome)

Choose Search Terms

Next, for each of your main concepts, choose several words or phrases that represent it - these will be your search terms. It's important to come up with alternatives, since there are many ways to refer to a concept. If you only use one, you may miss relevant articles.

There are two different types of search terms you can use: subject headings and keywords. For a comprehensive search, always use both:

Type of Search Term Description How Do You Choose Them?
Subject heading

Searching using preassigned terms representing topics or subjects for articles that have been "tagged" or labeled with that term. 

Each database uses its own subject headings. OVID Medline's are called MeSH. The subject headings are organized in a hierarchical tree. 
  • Use a subject heading lookup tool (e.g. for PubMed or Medline, use the MeSH browser)
  • In OVID databases (e.g. Medline, Embase, PsycINFO), use the "map term to subject heading" feature
  • Look for a thesaurus or subject heading list in other databases
Keyword (also known as "textword")

Searching the "record" of a database for the presence of specific words or phrases you choose yourself. The record does not include the full-text of the article. The search will usually check the title, abstract, and author-provided keywords, but you can specify the fields you want to search.
  • For each main concept (PICO item), brainstorm a list of synonyms or related terms that represent or describe it
  • Consider scientific vs. common names, alternate spellings, singular and plural forms, different word forms (e.g. noun, adjective)

Example

Concept Subject Heading (MeSH) Keywords
Malaria
  • Malaria
  • Malaria
  • Paludism
  • Plasmodium
Sub-Saharan Africa
  • Africa South of the Sahara
  • Sub-Saharan Africa
  • Subsaharan Africa
  • Africa South of the Sahara
Bednets
  • Mosquito Control
  • Mosquito Nets
  • Bed net(s)
  • Bednet(s)
  • Mosquito net(s)
Adoption
  • Health Behavior
  • Health Knowledge, Attitudes, Practice
  • Adoption
  • Ownership
  • Usage
  • Compliance
  • Acceptance
  • Barrier(s)
  • Facilitator(s)

Tip: Sometimes, the subject heading and keywords for a concept will be the same. Other times they won't match. It depends on the subject headings used by the database. 

Combine Search Terms

Boolean Operators

Once you've chosen your search terms, you're ready to combine them to create your search strategy.

Terms are combined using Boolean operators. They are a set of commands that search engines, online catalogues, and databases are able to understand. They also make searching more efficient by letting you combine dozens of queries into one search.

Boolean operators include: AND, OR, NOT, parentheses, truncation, and phrases

Need more help? See our page on Boolean operators. 

Narrow Your Search: AND, NOT

AND tells the search engine to only return results that contain all the words you've entered. Since the search is more specific and selective, you'll retrieve fewer results.

Example: malaria AND bednet

NOT tells the search engine to give you results that contain all of the words you entered except the word following NOT.

Example: smoking NOT cigars

Expand Your Search: OR, Truncation

OR tells the search engine to give your results that contain any of the terms you've entered. This creates a broader search, so you'll retrieve a greater number of results.

Example: bed net OR bednet OR mosquito net

Truncation (usually represented by an asterisk *) allows you to search for multiple endings of the same root word.

Example: Africa* = Africa, African, Africans; bednet* = bednet, bednets

Phrase Searching

Search for two or more words as a unit by putting them in quotation marks. This is especially useful for titles or phrases.

Example: "mosquito net"

NOTE: OVID databases like Medline, Embase, and PsycINFO automatically search for words you enter side by side (and that are not combined with a Boolean operator) as a phrase.

Combining Searches

By using parentheses, you can ask a search engine to perform several Boolean searches at the same time. The search engine will perform the search enclosed in parentheses first, before moving on to the other search terms.

Example: (malaria OR paludism OR plasmodium) AND ("bed net*" OR bednet* OR "mosquito net*") AND (adopt* OR own* OR usage OR compliance OR accept* OR barrier* OR facilitator*)

Additional Resources