How to Create a PRISMA Flow Diagram

The PRISMA 2020 flow diagram shows how many records were identified, screened, assessed and included, and why records were excluded. Its numbers must be consistent with your screening log, so keep careful counts from the beginning.

Main stages

1. Identification: records from databases and registers, and records from other methods (websites, organisations, citation searching); duplicates removed.
2. Screening: records screened (titles and abstracts), records excluded, reports sought for retrieval, reports not retrieved.
3. Eligibility and inclusion: reports assessed for eligibility, reports excluded with reasons, studies included in the review (and the reports of those studies).

Official templates are provided for new reviews and for updated reviews. Note the distinction between records (database entries), reports (documents) and studies (units of investigation, which can have multiple reports).

Making the numbers add up

• Records identified − duplicates removed = records screened.
• Records screened − records excluded = reports sought for retrieval.
• Reports sought − not retrieved = reports assessed.
• Reports assessed − excluded (with reasons) = reports of included studies.

Keep a log with one line per record and a status, so you can regenerate the counts.

Tools

You can draw the diagram in any graphics tool, or use MRN's free PRISMA flow diagram generator, which checks that the arithmetic is consistent. Use the official PRISMA templates as the reference.

Illustrative example

Invented for teaching. 2,400 records are identified; 2,050 remain after de-duplication; 1,900 are excluded at title and abstract; 150 reports are sought and 5 cannot be retrieved; 145 are assessed and 125 excluded with reasons (wrong population 40, wrong design 55, no relevant outcome 30); 20 reports are included, representing 18 studies.

Common pitfalls

• Counts that do not add up.
• Missing exclusion reasons.
• Confusing reports and studies.

Key takeaways

• Count as you go, and keep a log.
• Report reasons for full-text exclusion.

This page is general educational information about research methods. It is not medical, legal or regulatory advice; follow your institution's ethics board and your target journal's instructions.