A PRISMA flow diagram is a standardised visual summary of how studies move through a synthesis, from identification to final inclusion. The PRISMA flow diagram provides a visual overview of the different stages in a systematic review or meta-analysis, tracing every record from database searches through screening to the included set. PRISMA stands for Preferred Reporting Items for Systematic Reviews and Meta-Analyses, and the diagram is one of the most recognised tools in health research. The original guidelines were published in 2009.[1] The PRISMA 2020 flow diagram, developed by the PRISMA Group, including Hoffmann TC and colleagues, introduced an updated guideline that restructured the diagram into four phases.[2]
Key Takeaways
- The PRISMA 2020 flow diagram consists of four main phases: identification, screening, eligibility, and inclusion.
- PRISMA flow diagrams help researchers and readers understand the study selection process in reviews and meta analyses.
- As per the PRISMA 2020 guidelines, it is crucial to document every step of the study selection process, including the number of articles excluded at each stage and the exclusion reasons.
- PRISMA flow diagrams contribute to the overall quality and credibility of evidence syntheses.
- Tools such as the PRISMA2020 Shiny App generate compliant diagrams from data, or platforms like Systematicly produce them automatically as you screen.
What Is a PRISMA Diagram?
A PRISMA flow diagram illustrates how studies are identified, screened, and included or excluded for the review. PRISMA was designed to guide the transparent reporting of systematic reviews, and the diagram is the most visible expression of that goal. The PRISMA diagram is typically the first figure in the results section, giving readers an immediate summary of the study selection process.
PRISMA diagrams enhance transparency by allowing readers to understand data sourcing and inclusion decisions. The PRISMA flow diagram enhances the value of reviews by helping reporters achieve higher reliability and better explicitness in selecting relevant studies. According to Moher et al., the original statement established an evidence based minimum set of items that authors should report, including the diagram.[1] Examples of PRISMA flow diagrams can be found on the PRISMA webpage, and templates for PRISMA flow diagrams are available for download in editable Word and PDF formats.[3]
The PRISMA 2020 Update
The 2020 version is the current standard for reporting the study selection process in new projects. According to the authors, this update restructured the original into four clearly defined phases and added a separate column for non-database records.[2] According to Sohrabi et al., published in Int J Surg, the 2020 statement represents a significant update to the existing guidelines.[4]
Records Identified: The Identification Phase
Records identified is the first box, representing the total number of results returned from all searches combined. The identification phase documents records identified from databases, registers, and other sources. You should run searches for each database individually, applying relevant limits such as subject headings. The PRISMA flow diagram typically starts with the initial number of studies identified through database searches. According to the PRISMA-S extension by Rethlefsen et al. published in Syst Rev, search documentation should record each database searched, exact search strings, and dates.[5] The 2020 version separates records from databases from those identified via reference lists, citation tracking, and included searches from manual searches.
Records Removed Before Screening
This box was introduced in 2020 that was absent from the 2009 version. It captures entries removed through automated tools for removing duplicates, those marked as ineligible by automation, and those removed for other reasons. You must remove duplicate articles from your results to avoid evaluating titles multiple times. The flow diagram shows the number of studies remaining after removing duplicates and the number at each stage based on predefined eligibility criteria and exclusion criteria.
Screening and Full Text Assessment
The screening stage shows the number remaining after removing duplicates. Record the number of articles excluded during title and abstract assessment. Screen titles carefully. Titles and abstracts are assessed against predefined inclusion criteria and exclusion criteria. The number of reports sought for retrieval is calculated by subtracting those excluded from the total screened. After screening, assess the full text of articles to determine eligibility. The eligibility phase assesses full-text articles based on predefined criteria, including reasons for exclusion. According to Rethlefsen et al., common questions about tracking records through the research process include how to handle re-runs of searches.[6]
Records Excluded and Reports Excluded
Records excluded during screening and reports excluded during eligibility are documented separately. At the screening stage, records excluded after title and abstract assessment are counted as a single number. At the eligibility stage, reports excluded after full text assessment require specific reasons, such as wrong setting, wrong population, or wrong intervention. PRISMA flow diagrams may not always clearly communicate the reasons for study exclusions, which can affect transparency. Researchers often face difficulties in accurately counting and reporting the number of studies at each stage. Common challenges with PRISMA flow diagrams include ensuring accurate representation of the study selection process.
Reports Assessed for Eligibility
Reports assessed for eligibility represents the number of full text articles that underwent detailed evaluation. The count is the difference between reports sought for retrieval and reports not retrieved. The final number of studies included in the review is presented in the diagram. Each report must result in either inclusion or exclusion with documented reasons.
Data Extraction and the PRISMA Flow
Data extraction follows the screening and eligibility phases. Once the final set is determined, the team systematically extracts relevant data into structured forms. Systematicly automates data extraction from PDFs into 30+ structured fields using AI, keeping extraction connected to study-level decisions. For a deeper look at how AI-powered screening integrates with PRISMA-compliant documentation, see our validation study.
How to Create a Flow Diagram
To create a PRISMA flow diagram, you should first prepare by saving a copy from the PRISMA website. It is important to follow best practices to ensure clarity and accuracy.
| Step | Action | What to Record |
|---|---|---|
| 1 | Run database searches | Number of records identified per database; total combined results |
| 2 | Search other sources | Records from reference lists, grey literature |
| 3 | Remove duplicates | Number of duplicates removed |
| 4 | Screen titles and abstracts | Records screened; records excluded |
| 5 | Seek full text reports | Reports sought for retrieval; reports not retrieved |
| 6 | Assess full text for eligibility | Reports assessed; reports excluded with reasons |
| 7 | Finalise included studies | Number of studies included |
Use concise descriptions for each stage to enhance readability. Double-check the accuracy of the PRISMA flow diagram by cross-referencing it with the study selection process described in the text. One challenge is the need to update the diagram if changes occur during the review process, which can complicate documentation. The final number of articles included is determined by subtracting those excluded from the total assessed for eligibility.
PRISMA Flow Chart Tools and Templates
A PRISMA flow chart can be created manually using Word or PowerPoint templates, or generated automatically using specialised software. According to Haddaway et al., the PRISMA2020 R package and Shiny App produce compliant diagrams with interactivity for optimised digital transparency.[7] Automated tools like Prismaliser or Prisma Editor can generate diagrams directly from the schema file.
| Tool | Type | Strengths | Limitations |
|---|---|---|---|
| PRISMA2020 Shiny App | Free web app | Compliant; interactive; exports to multiple formats | Requires manual data entry; disconnected from workflow |
| Word/PDF templates | Free | Available from the official site; fully editable | Manual updates; error-prone for large projects |
| Traditional SR tools | Paid software | Some integration with screening data | Often limited to basic format; may need export steps |
| Systematicly | AI platform | Automatic generation from live data; full compliance; real-time updates | Newer platform |
Interpreting PRISMA flow diagrams can be difficult due to the complexity of the study selection process. Researchers may struggle with the consistency of terminology used in PRISMA flow diagrams, which can lead to confusion. According to Akl et al., the extension for living evidence syntheses provides additional guidance on updating diagrams as new evidence is incorporated.[8]
Reporting Systematic Reviews with PRISMA
Best practice requires that every project include a completed diagram. According to Sohrabi et al., the 2020 statement introduced expanded guidance on reporting the number of studies versus number of reports, addressing situations where multiple articles report on the same study.[4] For researchers beginning new systematic reviews, the complete PRISMA compliance guide covers all 27 checklist items. Understanding the differences between systematic reviews and meta analyses clarifies when a diagram should report on one or both synthesis types. Together, these preferred reporting items for systematic reviews and meta analyses ensure the research question, searches, and study selection are fully documented.[9] Explore our systematic review methodology hub and platform features for additional guidance.
Common Mistakes in PRISMA Diagrams
A PRISMA diagram that contains arithmetic errors or missing boxes undermines the credibility of the entire project. The most frequent mistakes include numbers that do not add up between different stages, failure to report records removed before screening, omitting exclusion reasons at the eligibility stage, and conflating records with reports. For example, reports sought for retrieval should equal records screened minus records excluded. Every number should be traceable and internally consistent.
Best Practices
Following established guidelines is essential for producing a diagram that meets journal requirements and supports reproducibility. The PRISMA guidelines and extensions, including PRISMA-S for search reporting and PRISMA-LSR for living syntheses, form a comprehensive framework.[5][8]
Frequently Asked Questions
What is it used for?
It is used to document the study selection process in a meta-analysis or evidence synthesis. It tracks the number of records at each stage, from initial identification through searches to the final set of included studies. The diagram helps authors demonstrate transparent, reproducible methodology.
How do I fill in the numbers on a PRISMA 2020 flow diagram?
Start with total records identified from all databases, then record those from non-database sources separately. Document records removed before screening, duplicates and automated removals. Track those excluded at screening, reports sought for retrieval, reports not retrieved, reports assessed for eligibility, and reports excluded with specific reasons. The final box shows the number of studies included.
What is the difference between records and reports in a PRISMA flow?
Records refer to individual database entries (one per title and abstract), whilst reports refer to individual publications. A single study may generate multiple reports. The 2020 version uses "records" for identification and screening phases and "reports" from the retrieval stage onwards.
Can I generate a compliant diagram automatically?
Yes. Tools such as the PRISMA2020 Shiny App generate compliant diagrams from data you enter. Systematicly produces them automatically from your live data, updating in real time as articles move through each phase.
Where can I find diagram templates?
Templates are available from the official site in Word, PDF, and editable graphic formats. The PRISMA2020 R package also generates compliant diagrams programmatically. For an example of a completed diagram, see the 2020 explanation and elaboration document.
PRISMA diagrams are non-negotiable for modern systematic reviews, but they represent just one piece of a larger reporting and analysis challenge. When your diagram needs to be accurate, timely, and traceable to every screening decision, automation becomes essential. Systematicly's end-to-end platform connects every decision across your entire workflow, producing diagrams that are automatically compliant, fully auditable, and publication-ready from day one.
Summary
The diagram is an essential component of transparent reporting, documenting how records move through identification, screening, eligibility, and inclusion phases. The 2020 update introduced separate tracking for database and non-database sources, a new box for records removed before screening, and clearer distinction between records and reports. Systematicly generates compliant diagrams automatically from your data, ensuring accuracy and saving hours of manual work.
Never miscalculate your PRISMA numbers again. Systematicly generates your flow diagram automatically from live screening data, tracks every decision with an audit trail, and exports publication-ready diagrams in one click. Start your free project and see your diagram build itself.
References
- Moher D, Liberati A, Tetzlaff J, Altman DG; The PRISMA Group. Preferred reporting items for systematic reviews and meta-analyses: the PRISMA statement. PLoS Med. 2009;6(7):e1000097. ↩
- Page MJ, McKenzie JE, Bossuyt PM, Boutron I, Hoffmann TC, Mulrow CD, et al. The PRISMA 2020 statement: an updated guideline for reporting systematic reviews. BMJ. 2021;372:n71. ↩
- Page MJ, Moher D, McKenzie JE. PRISMA 2020 explanation and elaboration: updated guidance and exemplars. BMJ. 2021;372:n160. ↩
- Sohrabi C, Franchi T, Mathew G, et al. PRISMA 2020 statement: what's new and the importance of reporting guidelines. Int J Surg. 2021;88:105918. ↩
- Rethlefsen ML, Kirtley S, Waffenschmidt S, et al.; PRISMA-S Group. PRISMA-S: an extension to the PRISMA statement for reporting literature searches in systematic reviews. Syst Rev. 2021;10(1):39. ↩
- Rethlefsen ML, Kirtley S, Waffenschmidt S, et al.; PRISMA-S Group. PRISMA 2020 and PRISMA-S: common questions on tracking records through the systematic review. J Med Libr Assoc. 2022;110(2):253-257. ↩
- Haddaway NR, Page MJ, Pritchard CC, McGuinness LA. PRISMA2020: an R package and Shiny app for producing PRISMA 2020-compliant flow diagrams, with interactivity for optimised digital transparency and open synthesis. Campbell Syst Rev. 2022;18(2):e1230. ↩
- Akl EA, Khabsa J, Iannizzi C, et al.; PRISMA-LSR Group. Extension of the PRISMA 2020 statement for living systematic reviews (PRISMA-LSR): checklist and explanation. BMJ. 2024;387:e079183. ↩
- Rethlefsen ML, Kirtley S, Waffenschmidt S, et al.; PRISMA-S Group. PRISMA-S: an extension to the PRISMA statement for reporting literature searches in systematic reviews. J Med Libr Assoc. 2021;109(2):174-200. ↩