Record the original strategy, databases, dates, and result counts, then log the rerun date, any strategy changes, and new records retrieved, and report both searches in the methods and flow diagram so the update is auditable.
Keep the baseline search record
The Cochrane Handbook describes documenting searches as part of planning and running systematic review searches, and PRISMA 2020 provides a checklist and flow diagrams for transparent reporting of methods and the studies found. Your baseline record should capture, for each database searched:
- the database name and interface used;
- the full search strategy as run, including field tags, filters, and limits;
- the date the search was executed;
- the number of records retrieved.
PubMed supports field tags, filters, Advanced Search, and saved searches, so a saved search can preserve the strategy you ran and give you a starting point for the rerun.
Run and log the rerun
- Retrieve the saved or documented strategy and confirm it matches the baseline record before executing it; note any difference you find.
- Run the search on the rerun date and record that date, the database, and the number of records retrieved.
- Compare the rerun strategy with the baseline and write down every change, such as added or removed terms, changed field tags, or altered date limits.
- Identify records retrieved by the rerun that were absent from the baseline, and log how many new records the rerun produced.
Report both searches
In the methods, describe the original search and the rerun as separate events, each with its databases, dates, strategy, and result counts, and state any strategy changes between them. In the flow diagram, show the records from each search so a reader can trace how the rerun contributed records to screening and inclusion. PRISMA 2020's flow diagrams support this kind of transparent reporting of what was found and included.
Check before you file the record
Confirm that the logged strategy reproduces the recorded result count when rerun, that every strategy change has a stated reason, and that the methods text and flow diagram report the same dates and counts.