Prepare your PRISMA flow diagram.

The Complete Guide to PRISMA 2020 Flow Diagrams for Systematic Reviews

The PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) flow diagram is a mandatory component of any systematic review. It provides a transparent visual summary of how you identified, screened, and selected studies for inclusion. The 2020 update brought significant changes to the original 2009 template, and understanding these changes is essential for getting your review published.

What Changed in PRISMA 2020?

The PRISMA 2020 statement, published by Page et al. in the BMJ, introduced several important updates to the flow diagram:

• Separate identification sources: The 2020 template distinguishes between records from databases/registers and records from other sources (websites, citation searching, etc.).
• Automation and deduplication tracking: There is now a dedicated box for records removed before screening, including duplicates and records removed by automation tools.
• Reports vs. studies distinction: The diagram now explicitly differentiates between reports (individual publications) and studies (unique research projects), acknowledging that one study may generate multiple reports.
• Previous studies: For updated reviews, the diagram now includes studies from previous versions of the review.

How to Complete Each Section of the PRISMA Flow Diagram

1. Identification

Record the total number of records identified from each source. Be specific about the databases searched (e.g., PubMed, Embase, CENTRAL, Web of Science) and the date of the last search. Include records from registers (such as ClinicalTrials.gov), citation searching, grey literature, and any other sources. The PRISMA 2020 diagram separates database/register searches from other methods of identification.

2. Screening

After removing duplicates, report the number of records screened by title and abstract. State how many were excluded at this stage. Then report how many full-text articles you attempted to retrieve, how many you could not retrieve (with reasons), and how many you assessed for eligibility. For each full-text article excluded, provide a reason.

The exclusion reasons should follow a hierarchy. A common approach is to apply the most important criterion first: wrong population, then wrong intervention, wrong comparator, wrong outcome, wrong study design. Each article is categorized by the first applicable reason.

3. Included

Report both the number of studies and the number of reports included. If some studies contributed data to quantitative synthesis (meta-analysis) while others were synthesized narratively, state both numbers.

Common Mistakes in PRISMA Flow Diagrams

1. Numbers that do not add up. Reviewers frequently check the arithmetic. The number screened minus excluded should equal the number sought for retrieval, and so on. Inconsistencies are an immediate red flag.
2. Using the old 2009 template. Many journals now require PRISMA 2020. Using the outdated template signals unfamiliarity with current standards.
3. Not specifying exclusion reasons. Simply stating the number excluded at full-text review without categorized reasons is insufficient. Each excluded article needs a documented reason.
4. Conflating reports and studies. If three papers report different outcomes from the same clinical trial, that is one study with three reports. Mixing these up can inflate your inclusion count.
5. Omitting sources. If you hand-searched reference lists or contacted authors for additional data, these sources must appear in the identification section.
6. Forgetting grey literature. Conference abstracts, dissertations, and unpublished studies should be documented if they were part of your search strategy.

Tools for Creating PRISMA Flow Diagrams

Several tools can help you create professional PRISMA flow diagrams. Our generator above creates a text-based version that you can paste into any document. For publication-quality figures, consider using dedicated software that produces editable vector graphics. Many researchers use Microsoft PowerPoint, draw.io, or LaTeX packages to create their final diagrams.

Regardless of the tool you use, the most important thing is accuracy. Double-check every number in your diagram against your records, and have a second reviewer verify the counts independently.

PRISMA 2020 Checklist Compliance

The flow diagram is just one part of the PRISMA 2020 checklist, which contains 27 items covering the title, abstract, introduction, methods, results, discussion, and funding. Many journals require authors to submit a completed PRISMA checklist alongside their manuscript, with page numbers for each item. Non-compliance is one of the top reasons systematic reviews are desk-rejected.

Tips for a Strong PRISMA Diagram

• Use clear, descriptive exclusion reason categories that align with your eligibility criteria.
• Include the date range of your database search in a footnote or the methods section.
• If you used automation tools (e.g., ASReview, Rayyan) for screening, note this in the identification section.
• For living systematic reviews, indicate the current search update date.
• Consider registering your protocol on PROSPERO before starting the review, as many journals require this.