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How to Conduct a Literature Review (Health Sciences and Beyond)

Overview of how to get started writing a health sciences literature review.

The Research Questions

A well-formulated research question:

  • starts your entire search process
  • provides focus for your searches
  • guides the selection of literature sources

Question formats are helpful tools researchers can use to structure a question that will facilitate a focused search. Such formats include: PICO, PEO, SPIDER, and COSMIN. Other formats can be found here. 


The PICO format is commonly used in evidence-based clinical practice. This format creates a "well-built" question that identifies four concepts: (1) the Patient problem or Population, (2) the Intervention, (3) the Comparison (if there is one), and (4) the Outcome(s).

Example: In adults with recurrent furunculosis (skin boils), do prophylactic antibiotics, compared to no treatment, reduce the recurrence rate? (Cochrane Library Tutorial, 2005)

P adults with recurrent furunculosis
I prophylactic antibiotics
C no treatment
O reduction in recurrence rate


The PEO question format is useful for qualitative research questions. Questions based on this format identify three concepts: (1) Population, (2) Exposure, and (3) Outcome(s).

Example: In infants, is there an association between exposure to soy milk and the subsequent development of peanut allergy (Levine, Ioannidis, Haines, & Guyatt, 2014)?

P infants
E exposure to soy milk
O peanut allergy


The SPIDER question format was adapted from the PICO tool to search for qualitative and mixed-methods research.  Questions based on this format identify the following concepts: (1) Sample, (2) Phenomenon of Interest, (3) Design, (4) Evaluation, and (5) Research type.

Example: What are young parents’ experiences of attending antenatal education? 

S young parents
P of I antenatal education
D questionnaire, survey, interview, focus group, case study, or observational study
E experiences
R qualitative or mixed method

Search for (S AND P of I AND (D OR E) AND R) (Cooke, Smith, & Booth, 2012).


The COSMIN (COnsensus-based Standards for the selection of health status Measurement INstruments) format is used for systematic review of measurement properties.  Questions based on this format identify (1) the construct or the name(s) of the outcome measurement instrument(s) of interest,  (2) the target population, (3) the type of measurement instrument of interest, and (4) the measurement properties on which the review focuses.

Visit the COSMIN website to view the COSMIN manual and checklist.