PRISMA flow diagram for an updated review
Updated 2026-10-12
When you update an earlier systematic review, the flow diagram has to show two things at once: what the previous version already included and what the new search added. PRISMA 2020 has templates for exactly this.
When to use the updated review template
Use it when your review builds on a previous published version: you rerun the searches from the last search date, screen the new results, and add any newly eligible studies to the ones already included. This covers a standard update, a living systematic review and a Cochrane update. If you are doing a fresh review on a topic someone else reviewed before, that is a new review and takes the new review template.
What is different in the updated template
The updated versions keep every box of the new-review diagram and add three things:
- A "Previous studies" column on the left, with two lines: studies included in the previous version of the review, and reports of studies included in the previous version.
- Headers that say "new studies": the search columns are titled "Identification of new studies via databases and registers" and, if used, "via other methods".
- Two boxes at the bottom: new studies included in the review (with reports of new included studies), then total studies included in the review (with reports of total included studies).
As with new reviews, there are two versions: databases and registers only, or with other methods as well.
How to fill it in
- Previous studies. Take the number of included studies, and the number of reports, from the published previous version.
- New search. Enter only the records found by the update search, for each database and register. Do not add the original search results again.
- Screening and eligibility. Fill these in for the new records only, exactly as you would for a new review.
- New studies included. Give the studies and reports that came out of the new search.
- Totals. Add previous and new together for studies, and separately for reports.
A worked example
Suppose the previous version of a review included 18 studies described in 21 reports. The update search then runs like this:
| Box | Count | Check |
|---|---|---|
| Records identified by the update search | 640 | |
| Duplicate records removed | 110 | |
| Records screened | 530 | 640 − 110 |
| Records excluded | 480 | |
| Reports sought for retrieval | 50 | 530 − 480 |
| Reports not retrieved | 2 | |
| Reports assessed for eligibility | 48 | 50 − 2 |
| Reports excluded, with reasons | 41 | |
| New studies included (reports) | 6 (7) | 48 − 41 = 7 reports |
| Total studies included (reports) | 24 (28) | 18 + 6 studies; 21 + 7 reports |
Seven new reports describe six new studies, because one trial was published in two papers. That is why studies and reports are counted separately.
Situations that cause trouble
- A new report of a study you already included. A later follow-up paper adds a report but not a study. Count it in the reports total and leave the study total alone, and say so in a footnote or the results text.
- A previously included study is now excluded. If your eligibility criteria changed, the "previous studies" figure may no longer match the published version. Report the number you are carrying forward and explain the difference in the text.
- The update search overlaps the old one. Rerunning from a slightly earlier date is good practice, but records you already screened last time should be removed before screening, as duplicates or under "other reasons", with a note.
- More than one update. "Previous studies" means everything included up to the last published version, not only the original review.
- Living reviews. Redraw the diagram at each published update, with the previous version's totals moved into the left column.
Build it
In the generator, choose one of the two updated review templates. The previous studies column and the new and total boxes appear automatically, and you can check each subtraction against the table above. For the general steps, see how to make a PRISMA flow diagram.
Quick answers
Do I include the original search results in an updated review diagram?
No. The identification boxes show only the records from the update search. The earlier work is summarised in the previous studies column.
What goes in the previous studies box?
The number of studies included in the previous version of the review, and the number of reports of those studies.
How do I get the total studies included?
Add the studies from the previous version to the new studies included from the update search. Do the same, separately, for reports.
Source of the flow diagram wording: Page MJ, McKenzie JE, Bossuyt PM, et al. The PRISMA 2020 statement: an updated guideline for reporting systematic reviews. BMJ 2021;372:n71. doi:10.1136/bmj.n71. Licensed CC BY 4.0. This site is independent and not affiliated with the PRISMA or EQUATOR Network groups.