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Systematic Review Guide

A literature search for a systematic review is notably more rigorous and structured than for other types of research projects to ensure that all relevant studies are identified for inclusion in the analysis. Key considerations and reporting requirements are explained below.

However, the principles of literature searching set out in this Toolkit's literature searching guide remain the same. For training, visit the Education & Training page to register for a literature searching webinar or access recordings in LATTE.

The searching process in a systematic review is the systematic and comprehensive identification of all relevant studies related to the review question. It involves developing and running structured search strategies across multiple databases and sources to ensure the evidence base is complete, unbiased, and reproducible.

Why is it important to conduct the search thoroughly?

  • Ensures completeness by capturing all relevant studies, reducing the risk of missing key evidence.
  • Minimises bias by avoiding selective inclusion of studies that could skew results.
  • Supports transparency and reproducibility by allowing others to verify and replicate the search.
  • Saves time later – a well-designed search reduces irrelevant results and screening workload.
  • Provides a solid foundation as all later stages of the review depend on the quality of the search.

How do I conduct a systematic search?

A brief step by step is below, with further details outlined in this guide:

  1. Define the question and eligibility criteria
  2. Identify concepts and keywords
    1. Break the question into main concepts and list synonyms, acronyms, spelling variants, and related terms.
  3. Choose databases and sources
    1. Select at least 3 databases (e.g. Ovid MEDLINE, Ovid Embase, Cochrane Library, PsycINFO), trial registers, grey literature sources, and relevant organisational repositories.
  4. Build search strategies
    1. For each database, combine subject headings (e.g. MeSH/Emtree) with free-text terms using Boolean operators, proximity and truncation. Tailor syntax to each platform.
    2. Avoid restrictive filters (e.g. language, date) unless justified; if used, document and justify them.
    3. Test your gold set articles to see if they are returned in your search
  5. Run supplementary searches
    1. Hand-search reference lists, citation-tracking (forward/backward), contact experts, search trial registries and conference abstracts, and check preprint servers if relevant.
  6. Document everything
    1. Save full search strings, dates run, databases searched, number of records retrieved and any limits applied for the methods section and PRISMA flowchart.
  7. Export, de-duplicate and manage records
    1. Covidence is an easy to use tool for this process
  8. Re-run or update searches close to submission to capture newly published studies; document the update date.

Recommended resources:

Literature Searching Guide

Request Research Support

Grey Literature Guide

Documenting your search in a systematic review means recording all details of how the literature search was designed, conducted, and managed to ensure transparency and reproducibility. According to the PRISMA guidelines, this includes reporting the databases searched, full search strategies, dates of searches, applied limits or filters, and the number of records identified and screened.

This documentation allows others to verify, replicate, and update the review’s search process.

Why is it important to document your search?

  • Shows exactly how the evidence was identified and selected, supporting reproducibility. 
  • Demonstrates rigour and credibility, meeting PRISMA reporting standards.
  • Saves time for future updates – clear documentation makes it easier to rerun or refine searches later.

How do I document my search?

  1. Save full search strategies
    1. Copy the exact search string used for each database (including controlled vocabulary and free-text terms), and keep a text file or PDF of each.
  2. Record the date each search was run (day, month, year) and the date of any updates.
  3. Name every database, platform (e.g. Ovid MEDLINE, Ovid Embase), registry, preprint server and grey literature source searched.
  4. Note any language, date or publication-type limits and justify them in the methods.
  5. Record the number of records retrieved from each source
  6. Export results
  7. Record supplementary searches
    1. Document handsearching, reference checking, citation tracking, conference searches, and contacts with experts (who was contacted, when, and what was received).
  8. Prepare PRISMA items — collate the above for the Methods section and complete the PRISMA flow diagram with the numbers at each stage (identified, screened, eligible, included).

Recommended resources:

Rerun a search

Rerunning your search in a systematic review means updating the original literature search at a later date to identify any newly published or indexed studies since the initial search was completed. This ensures that the review remains current, comprehensive, and reflective of the latest evidence, as recommended by the PRISMA 2020 guidelines and best practice standards for evidence synthesis.

Why is it important to rerun your search?

  • Captures new studies published since the original search.
  • Prevents outdated conclusions
  • Aligns with PRISMA standards
  • Facilitates publication – journals often require an updated search before submission.

When should you rerun your search?

  • It is recommended to rerun a search every 6 months until your review is completed.

How do you rerun a search?

The below table includes search strings you can add to your existing search to limit it to a particular date range.

Note: If it has been longer than 12 months consider re-checking your subject headings as they may have been updated or new subject headings added. MeSH is updated annually.  

Database Line command Example
MEDLINE (Ovid)

limit x to dt=YYYYMMDD-YYYYMMDD 

  • x is the number of the last row in your search 
  • First date entered could be when you last searched 
  • Second date entered could be the date you rerun the search 
  • Dt - is the date when the record was created in Medline, not the publication date 

limit 12 to dt=20230101-20240422 

Limits line 12 to between 1st Jan 2023 to 22nd April 2024
Embase and Emcare (Ovid)

limit x to dc=YYYYMMDD-YYYYMMDD 

  • x is the number of the last row in your search 
  • First date entered could be when you last searched 
  • Second date entered could be the date you rerun the search 
  • Dc - is the date when the record was created in Embase/Emcare, not the publication date

limit 12 to dc=20230101-20240422 

Limits line 12 to between 1st Jan 2023 to 22nd April 2024
PsycINFO (Ovid)

limit x to up=YYYYMMDD-YYYYMMDD

  • x is the number of the last row in your search 
  • First date entered could be when you last searched 
  • Second date entered could be the date you rerun the search 
  • Up - is the date when the record was created in PychINFO, not the publication date

limit 12 to up=20230101-20240422 

Limits line 12 to between 1st Jan 2023 to 22nd April 2024
CINAHL*

EM YYYYMMDD- 

EM YYYYMMDD-YYYYMMDD 

  • EM - ‘entry date’ can be used with a hyphen ('on or after' the date) or range 
  • use AND to join this line to the last line of your search 

EM 20230101-20240422 

Limits results to between 1st Jan 2023 to 22nd April 2024 
Scopus*

ORIG-LOAD-DATE AFT YYYYMMDD 

  • use AND to join this line to the last line of your search

AND ORIG-LOAD-DATE AFT 20230101 

Limits search results to records added after 1st Jan 2023

* Not accessible via Monash Health. May be accessible via a university affiliation

Adapted from source: University of SA Library- https://guides.library.unisa.edu.au/SystematicReviews/UpdateASearch