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Writing in the Health and Social Sciences: Literature Reviews and Synthesis Tools

Guide to writing, citing, and publishing resources for the health and social sciences.

Systematic Literature Reviews: Steps & Resources

The steps for conducting a systematic literature review are listed below. 

Also see subpages for more information about:

  • What are Literature Reviews?
  • Conducting & Reporting Systematic Reviews
  • Finding Systematic Reviews
  • Tools & Tutorials

Literature Review & Systematic Review Steps

1. Develop a Focused Question

2. Scope the Literature

3. Refine & Expand the Search

4. Limit the Results

5. Download Citations

6. Abstract & Analyze

7. Create Flow Diagram

8. Synthesize & Report Results

1. Develop a Focused Question 

Consider the PICO Format: Population/Problem, Intervention, Comparison, Outcome

Focus on defining the Population or Problem and Intervention (don't narrow by Comparison or Outcome just yet!)

Example:

"What are the effects of the Pilates method for patients with low back pain?"
 

Tools & Additional Resources:

  • PICO Question Help
  • Templates & Definitions for Types of PICO Questions
    • Stillwell, Susan B., DNP, RN, CNE; Fineout-Overholt, Ellen, PhD, RN, FNAP, FAAN; Melnyk, Bernadette Mazurek, PhD, RN, CPNP/PMHNP, FNAP, FAAN; Williamson, Kathleen M., PhD, RN Evidence-Based Practice, Step by Step: Asking the Clinical Question, AJN The American Journal of Nursing: March 2010 - Volume 110 - Issue 3 - p 58-61 doi: 10.1097/01.NAJ.0000368959.11129.79

2. Scope the Literature

A "scoping search" investigates the breadth and/or depth of the initial question or may identify a gap in the literature. 

Eligible studies may be located by searching in:

  • Background sources (books, POC tools)
  • Article databases
  • Trial registries
  • Grey literature
  • Cited reference searching
  • Reference lists

When searching, if possible, translate terms to controlled vocabulary of the database. Use text word searching when necessary.

Use Boolean operators to connect search terms:

  • Combine separate concepts with AND (resulting in a narrower search)
  • Connecting synonyms with OR (resulting in an expanded search)

Example:

Search: pilates AND ("low back pain" OR backache)

Tools & Additional Resources:


3. Refine & Expand Your Search

Expand your search strategy with synonymous search terms harvested from:

  • database thesauri
  • reference lists
  • relevant studies

Example: 

(pilates OR exercise movement techniques) AND ("low back pain" OR backache* OR sciatica OR lumbago OR spondylosis)

Tools & Additional Resources:

As you develop a final, reproducible strategy for each database, save your strategies in a:

  • a personal database account (e.g., MyNCBI for PubMed)
  • A spreadsheet or word document

4. Limit Your Results

Use database filters to limit your results based on your defined inclusion/exclusion criteria.  In addition to relying on the databases' categorical filters, you may also need to manually screen results.  

Example:

Limit to Article type, e.g.,:  "randomized controlled trial" OR multicenter study
Limit by publication years, age groups, language, etc.

NOTE: Many databases allow you to filter to "Full Text Only".  This filter is not recommended. It excludes articles if their full text is not available in that particular database (CINAHL, PubMed, etc), but if the article is relevant, it is important that you are able to read its title and abstract, regardless of 'full text' status. The full text is likely to be accessible through another source (a different database, or Interlibrary Loan).  

Tools & Additional Resources:


5. Download Citations

Selected citations and/or entire sets of search results can be downloaded from the database into a citation management tool. If you are conducting a systematic review that will require reporting according to PRISMA standards, a citation manager can help you keep track of the number of articles that came from each database, as well as the number of duplicate records.

Example:

In Zotero, you can create a Collection for the combined results set, and sub-collections for the results from each database you search.  You can then use Zotero's 'Duplicate Items" function to find and merge duplicate records.

File structure of a Zotero library, showing a combined pooled set, and sub folders representing results from individual databases.

Tools & Additional Resources:


6. Abstract and Analyze

  • Migrate citations to data collection/extraction tool
  • Screen Title/Abstracts for inclusion/exclusion
  • Screen and appraise full text for relevance, methods, 
  • Resolve disagreements by consensus

Example

Covidence is a web-based tool that enables you to work with a team to screen titles/abstracts and full text for inclusion in your review, as well as extract data from the included studies.

Screenshot of the Covidence interface, showing Title and abstract screening phase.

Tools & Additional Resources


7. Create Flow Diagram

The PRISMA (Preferred Reporting Items for Systematic reviews and Meta-Analyses) flow diagram is a visual representation of the flow of records through different phases of a systematic review.  It depicts the number of records identified, included and excluded.  It is best used in conjunction with the PRISMA checklist.

Example

Example of a PRISMA flow diagram showing number of records identified, duplicates removed and records included/excluded

Example from Navarra, A.-M. D., Gwadz, M. V., Whittemore, R., Bakken, S. R., Cleland, C. M., Burleson, W., … Melkus, G. D. (2017). Health Technology-Enabled Interventions for Adherence Support and Retention in Care Among US HIV-Infected Adolescents and Young Adults: An Integrative Review. AIDS and Behavior. https://doi.org/10.1007/s10461-017-1867-6

Tools & Additional Resources

  • PRISMA Diagram Templates (Word and PDF)
  • Editable PRISMA Diagram - NYU Libraries (Google Drawing)
    • Log in with your NYU credentials
    • Make a copy of the file to fill out the template
    • Image can be downloaded as PDF, PNG, JPG, or SVG
  • Covidence generates a PRISMA diagram that is automatically updated as records move through the review phases

8. Synthesize & Report Results

There are a number of reporting guideline available to guide the synthesis and reporting of results in systematic literature reviews.

Example

It is common to organize findings in a matrix, also known as a Table of Evidence (ToE).

Example of a review matrix showing the results of a systematic literature review

Tools & Additional Resources


Steps modified from: 

Cook, D. A., & West, C. P. (2012). Conducting systematic reviews in medical education: a stepwise approach.  Medical Education, 46(10), 943–952.