Skip to Main Content

Knowledge Synthesis Guide

Overview of evidence synthesis steps and resources to assist researchers conducting reviews

What is a PRISMA Flow Diagram?

The flow diagram depicts the flow of information through the different phases of a systematic review. It maps out the number of records identified, included and excluded, and the reasons for exclusions. Different templates are available depending on the type of review (new or updated) and sources used to identify studies:

  • PRISMA 2020 flow diagram for new systematic reviews which included searches of databases and registers only (Word)

  • PRISMA 2020 flow diagram for new systematic reviews which included searches of databases, registers and other sources (Word)

  • PRISMA 2020 flow diagram for updated systematic reviews which included searches of databases and registers only (Word)

  • PRISMA 2020 flow diagram for updated systematic reviews which included searches of databases, registers and other sources (Word)

Note: The PRISMA 2020 flow diagram templates are distributed in accordance with the terms of the Creative Commons Attribution (CC BY 4.0) license, which permits others to distribute, remix, adapt and build upon this work, for commercial use, provided the original work is properly cited. To view a copy of this license, visit https://creativecommons.org/licenses/by/4.0/

Although there are different types of the PRISMA Flow diagram depending on your research, a simple PRISMA diagram could look like this after you complete your screening process (click on image to see larger version in new window):

sample prisma diagram

Step-by-step: PRISMA 2020 Flow Diagram

Step 1: Preparation To complete the the PRISMA diagram, save a copy of the diagram to use alongside your searches. It can be downloaded from  the PRISMA website. It is an editable word document. It is just a template, you can adjust as needed. 

Step 2: Run your searches Run the search for each database individually. As you download the results file from database you should have a final number of records or articles for each database. Enter this information in the top left box of the PRISMA flow chart. You should add the total number of combined results from all databases (including duplicates) after the equal sign where it says Databases (n=). It is also best practice to add the number of results from each database search, for example, Medline (n=335), CINAHL (n= 600), and so on.  If you search trial registers, such as ClinicalTrials.gov or others, you should enter that number after the equal sign in Registers (n=).

NOTESome citation managers automatically remove duplicates with each file you import. Be sure to capture the number of articles from your database searches before any duplicates are removed.

prisma records retrieved

 

Step 3: Remove All Duplicates To avoid reviewing duplicate articles, you need to remove any articles that appear more than once in your results. You may want to export the entire list of articles from each database to a citation manager such as EndNote or Zotero and remove the duplicates there. Or, if you are using a screening tool such as Distiller you can choose to use the de-duplication tool provided in the application. Enter the number of records removed as duplicates in the second box on your PRISMA template. If you are using automation tools to help evaluate the relevance of citations in your results, you would also enter that number here.

prisma records removed

 

Step 4: Records Screened- Title/Abstract Screening (Level 1) The next step is to add the number of articles that you will screen. This should be the number of records identified minus the number from the duplicates removed box.

prisma records screened level 1

 

Step 5: Records Excluded- Title/Abstract Screening (Level 1) You will need to screen the titles and abstracts for articles which are relevant to your research question. Any articles that appear to help you provide an answer to your research question should be included. Record the number of articles excluded through title/abstract screening in the box to the right titled "Records excluded." You do not need to indicate exclusion reasons at this level, but they are required in full text screening.

prisma records excluded level 1

 

Step 6: Reports Sought for Retrieval This is the number of articles you obtain in preparation for full text screening.  Subtract the number of excluded records (Step 5) from the total number screened (Step 4) and this will be your number sought for retrieval.

prisma records for retrieval

 

Step 7: Reports Not Retrieved List the number of articles for which you are unable to find the full text.  Remember to use Interlibrary Loan to request articles to see if we can obtain them from other libraries before automatically excluding them.

prisma records not retrieved

 

Step 8: Reports Assessed for Eligibility- Full Text Screening (Level 2) This should be the number of reports sought for retrieval (Step 6) minus the number of reports not retrieved (Step 7). Review the full text for these articles to assess their eligibility for inclusion in your knowledge synthesis. 

prisma level 2 screening

 

Step 9: Reports Excluded - Full Text Screening (Level 2) After reviewing all articles in the full-text screening stage for eligibility, enter the total number of articles you exclude in the box titled "Reports excluded," and then list your reasons for excluding the articles as well as the number of records excluded for each reason.  Examples include wrong setting, wrong patient population, wrong intervention, wrong dosage, wrong context etc.  You should only count an excluded article once in your list even if if meets multiple exclusion criteria.

prisma level 2 exclusions

 

Step 10: Included Studies The final step is to subtract the number of records excluded during the eligibility review of full-texts (Step 9) from the total number of articles reviewed for eligibility (Step 8). Enter this number in the box labeled "Studies included in review." You have now completed your PRISMA flow diagram, unless you have also performed searches in non-database sources.

prisma studies included in review

 

The format of the PRISMA Step-By-Step was first developed by Glasgow Caledonian University
https://www.gcu.ac.uk/library

Creative Commons Licence