Introduction to Systematic Literature Search Developing a comprehensive search strategy Databases to search Practical demonstration of Systematic Literature Search with Pubmed

1. SYSTEMATIC LITERATURE SEARCH
Alison A. Kinengyere (PhD)
Systematic Reviews Workshop: 19-21 September 2023

2. Learning outcomes
By the end of the module, participants will
be able to:
•Develop an effective search strategy
•Identify the sources to conduct a systematic
literature search
•Comprehensively and exhaustively search for & find
literature on a particular topic

3. Outline
• Introduction
• Learning outcomes
• Importance of systematic literature searching
• Developing a search strategy (search
techniques, search process)
• Putting it all together
• Exercise
• Summary

4. Introduction
Definition of a systematic review
•a comprehensive & structured approach to summarizing &
synthesizing existing research evidence on a specific topic
•Process that follows predefined & transparent criteria to
identify, collect, assess, & analyze relevant studies from the
available literature
•Provide an unbiased & objective summary of the current state
of knowledge on a particular subject

5. Key characteristics of
systematic reviews
• Formulating a RQ or defining
a clear, specific research
objective
• Developing inclusion &
exclusion criteria to
determine which studies are
eligible for inclusion
• Conducting a comprehensive
& systematic search of
literature to identify relevant
studies
• Screening & selecting studies
based on the predefined
criteria,
• Extracting data from selected
studies using standardized
forms
• Assessing the quality & RoB
of included studies, often
using established tools or
checklists

6. Introduction…
• Therefore, literature search is one of the
most important steps in the systematic
review process
• It is the foundation of the systematic
review
• Need to understand the importance of
systematic literature search & its role in
producing a robust systematic review

7. Session coverage
Essential components & best practices for
conducting a systematic literature search as
part of the systematic review process

8. The importance of systematic
literature searching
• Minimizing Bias
• Comprehensiveness
• Transparency (reproducibility)
• Evidence quality
• Informed decision-making

9. Developing the search
strategy
• A search strategy is an organized
structure of key terms used to search a
database
• SRs require not only top-notch search
results, but reproducibility

10. Steps in the search process
• Scoping your search topic (define & refine question)
• Break down the question into concepts-PICO/ST
• Think about synonyms & best combinations of key concepts
• Identify sources to search
• Compile your search strategy & test it
• Run your search (you may need to revise & re-test your
search)
• Adapt strategy to different databases
• Find the full text
• Manage your information

11. Structuring your search strategy
using the PICO/ST framework
• Frameworks are used to
break up the research
topic into key concepts &
in the developing of
research questions
• There are various
frameworks/mnemonics
that can assist you break
up the research topic into
key concepts

12. PICO
• Reviews of interventions for health, appropriate
for quantitative studies
• Patient or population
• Intervention
• Comparator
• Outcomes
PICO(M) PICO(T) PIO PICO(C)

13. • As much as these appear common in the
health sciences, there are a number of
frameworks beyond health
sciences…also not limited to
quantitative studies but also qualitative
studies

14. Example of a PICOS question
“Is the amount of environmental tobacco smoke exposure in
infancy as measured by infant urinary and hair cotinine levels,
associated with the occurrence of childhood cancer by age 14?”
•Population - Infant
•Intervention - environmental tobacco smoke exposure
•Comparison - no environmental tobacco smoke
exposure
•Outcome - childhood cancer
•S - SSA

15. Search techniques
• Synonyms
• Subject headings
• Boolean operators
(AND, OR, NOT)
• Truncation
•Abbreviations (Human
immunodeficiency
syndrome & AIDS
•Proximity searching
•Filters/Hedges

16. Synonyms – related words
What are the Environmental effects of conversion
of cropland to forest programs in SSA?

17. Is the amount of environmental tobacco smoke exposure in infancy as measured by
infant urinary & hair cotinine levels, associated with the occurrence of childhood
cancer by age 14?
Population Intervention Comparison Outcome Setting
Infant
Newborn
environmenta
l tobacco
smoke
exposure
No
environmental
tobacco smoke
exposure
childhood
cancer
Neoplasms
Tumor
Neoplasia
Sub Saharan Africa
SSA
Africa South of the
Sahara
(all countries in SSA)

18. Synonyms retrieve more

19. Subject headings

20. Boolean operators
• The power of Boolean searching is based
on connecting keywords using Boolean
operators
• The basic operators are OR, AND & NOT
• Operators are used to limit, widen or
define searches

21. Boolean operator OR
Forest OR forestry OR
woodland OR forestland

22. Boolean operator AND

23. Boolean Operator NOT
cats NOT dogs. This
excludes information that
has both cats and dogs

25. Truncation
• Different work endings & wild cards
• Truncation finds alternative endings to
words
• Enter the beginning of the word, then end
with the truncation symbol (usually*)
• Example: For forestry, you can use forest*
to find words forestry, forests, forestland

26. Impact of increased complexity on
comprehensiveness of results

27. Proximity searching
• Look for words in the same sentence or
within n words of each other
• Useful when the vocabulary used to
describe your subject is variable

28. Hedges and filters
Tested searches for common elements (methodology or population) &
shared for others' use
•Geographic hedges to limit search to only certain regions – e.g. LMICs /
SSA … (Source: Cochrane EPOC LMIC Filter:
https://epoc.cochrane.org/lmic-filters )
•Study design filters to limit search by study design – e.g.
Quasi-experimental studies (Source: Glanville et al 2017
https://pubmed.ncbi.nlm.nih.gov/28365309/ )
•Population hedges to limit search to certain populations- e.g. Sexual
minority groups (Source: Canadian Health Libraries Association
https://extranet.santecom.qc.ca/wiki/!biblio3s/doku.php?id=concepts:
minorite-sexuelle

29. Putting it all together
1. Environmental OR Ecological OR Conservational OR
Flooding OR Soil erosion
2. Cropland conversion OR Tree planting OR Training
local farmers OR Farmer compensation
3. 1 AND 2
4. Forests OR Forestry OR Woodland OR Forestland
5. 3 AND 4

30. Putting it all together
(Environmental OR Ecological OR Conservational OR
Flooding OR Soil erosion) AND (Cropland conversion OR
Tree planting OR Training local farmers OR Farmer
compensation) AND (Forests OR Forestry OR Woodland
OR Forestland) AND (Sub-Saharan Africa OR Africa South of
the Sahara OR Uganda OR Kenya OR Tanzania)

31. Peer review of search
strategies
• Minimizes errors
• May identify missed terms
• Reduces risk of bias
Walk away and revisit with fresh eyes 1-2
days later!

32. Run the search
pg. 16

33. Finding full articles
Routes to access
Check with your librarian what your institution uses to access
e-resources.

34. Some of the databases
• PubMed
• EMBASE
• EBSCO
• EMERALD
• WEB OF SCIENCE
• ECONLIT

35. References
• A Guide to Evidence Synthesis: Evidence
Synthesis Institute for Librarians -
https://guides.library.cornell.edu/eviden
ce-synthesis/trainings
• Higgins et al (editors). Cochrane
Handbook for Systematic Reviews of
Interventions version 6.3 ,2022-
https://training.cochrane.org/handbook

36. Exercise
What are the critical factors which support on inhibit
the effective implementation of the One Health
approach in Kenya, Ethiopia and Uganda?
1.Identify keywords per concept
2.Using the search techniques learnt, develop a search string
3.Run the search in PubMed at: https://pubmed.ncbi.nlm.nih.gov/
4.Restrict the search to publication dates: 2013-2023

37. *