What Is a PRISMA Flow Diagram?

The PRISMA Statement guidelines were designed to improve how systematic reviews and meta-analyses are reported. They consist of a 27-point PRISMA Systematic Review Checklist and a 4-stage flow diagram, both of which help promote transparency and organization in the systematic review process. The PRISMA flow diagram depicts how information flows through the different phases of the review. It maps out the number of records identified, included, and excluded, plus the reasons for exclusions.

Types of PRISMA Flow Diagrams

There are two main types of PRISMA flow diagrams, expanded from the previous version (the current one is for 2020). The first version includes databases and clinical trial or preprint registers. The second includes extra sections to elaborate on gray literature (eg, searches on websites or within citation lists).

Both types of PRISMA flow diagrams are available in template form from the PRISMA website. Choosing which one to use depends on the type of review (whether it is new or an update) and the sources used to identify studies. If you’re unsure, check out our recent PRISMA diagram example.

Steps to Making a PRISMA Flow Diagram

The PRISMA flow diagram can be divided into 3 phases: identification, screening, and inclusions (and exclusions). Here’s a breakdown of the steps to completing it.

Prepare the Diagram

Get a PRISMA flow diagram template from the PRISMA website and save it alongside your searches.

Run Database Searches

Run a search for each database you’re using; include all of your search terms, subject headings, truncation, and/or wildcards, and apply the relevant limits. Once you do this, you should have a final number of records for each database, which you must enter in the top left box of your flow chart. You can also add notations in the box for the number of results you get from each database search.

Remove Duplicate Articles

Remove any articles that appear more than once in your results and enter the number of removed duplicates in the second box of the template.

Add Articles to Screen

Add the number of articles to be screened, which should be the number of identified records minus the removed duplicates.

Screen Articles to Exclude

Screen your articles to ensure you only include those that are relevant to your search questions. Any articles that are excluded should be counted and the number must be noted in the box titled “records excluded.” You can also add reasons for exclusion here, but that is optional.

Record Reports Sought for Retrieval

Reports sought for retrieval are those that you obtain in preparation for full-text screening. This will be the total number of articles to be screened minus the number of “records excluded.”

Record Reports Not Retrieved

List the number of articles for which you can’t find the full text after using the necessary tools and resources.

Assess Eligibility of Articles for Inclusion

The number of reports assessed for eligibility should be the number of reports sought for retrieval minus the number of reports not retrieved. In this step, review the full text of these articles to determine if they are eligible to be included in the systematic review.

Enter Total Number of Reports Excluded

After a review of all the articles in the full-text screening stage for eligibility, input the total number of articles from “reports excluded.” Make sure an article meets exclusion criteria before adding them here; you are obliged to explain why you made the exclusions (eg, wrong setting, wrong population, wrong intervention).

List the Studies Included in the Review

Subtract the number of excluded records during the eligibility review of full texts from the total number of articles reviewed for eligibility, then put this number in the box labeled “studies included in review.”

The PRISMA Statement guidelines were designed to improve how systematic reviews and meta-analyses are reported. They consist of a 27-point PRISMA Systematic Review Checklist and a 4-stage flow diagram, both of which help promote transparency and organization in the systematic review process. The PRISMA flow diagram depicts how information flows through the different phases of the review. It maps out the number of records identified, included, and excluded, plus the reasons for exclusions.

Types of PRISMA Flow Diagrams

There are two main types of PRISMA flow diagrams, expanded from the previous version (the current one is for 2020). The first version includes databases and clinical trial or preprint registers. The second includes extra sections to elaborate on gray literature (eg, searches on websites or within citation lists).

Both types of PRISMA flow diagrams are available in template form from the PRISMA website. Choosing which one to use depends on the type of review (whether it is new or an update) and the sources used to identify studies. If you’re unsure, check out our recent PRISMA diagram example.

Steps to Making a PRISMA Flow Diagram

The PRISMA flow diagram can be divided into 3 phases: identification, screening, and inclusions (and exclusions). Here’s a breakdown of the steps to completing it.

Prepare the Diagram

Get a PRISMA flow diagram template from the PRISMA website and save it alongside your searches.

Run Database Searches

Run a search for each database you’re using; include all of your search terms, subject headings, truncation, and/or wildcards, and apply the relevant limits. Once you do this, you should have a final number of records for each database, which you must enter in the top left box of your flow chart. You can also add notations in the box for the number of results you get from each database search.

Remove Duplicate Articles

Remove any articles that appear more than once in your results and enter the number of removed duplicates in the second box of the template.

Add Articles to Screen

Add the number of articles to be screened, which should be the number of identified records minus the removed duplicates.

Screen Articles to Exclude

Screen your articles to ensure you only include those that are relevant to your search questions. Any articles that are excluded should be counted and the number must be noted in the box titled “records excluded.” You can also add reasons for exclusion here, but that is optional.

Record Reports Sought for Retrieval

Reports sought for retrieval are those that you obtain in preparation for full-text screening. This will be the total number of articles to be screened minus the number of “records excluded.”

Record Reports Not Retrieved

List the number of articles for which you can’t find the full text after using the necessary tools and resources.

Assess Eligibility of Articles for Inclusion

The number of reports assessed for eligibility should be the number of reports sought for retrieval minus the number of reports not retrieved. In this step, review the full text of these articles to determine if they are eligible to be included in the systematic review.

Enter Total Number of Reports Excluded

After a review of all the articles in the full-text screening stage for eligibility, input the total number of articles from “reports excluded.” Make sure an article meets exclusion criteria before adding them here; you are obliged to explain why you made the exclusions (eg, wrong setting, wrong population, wrong intervention).

List the Studies Included in the Review

Subtract the number of excluded records during the eligibility review of full texts from the total number of articles reviewed for eligibility, then put this number in the box labeled “studies included in review.”