Start from the missed study, search the reference lists of reviews that cite it, screen the retrieved records, then add eligible studies to your screening log and update the PRISMA flow counts. Cochrane Handbook Chapter 4 treats reference-list searching as one documented search method within a planned search, and PRISMA 2020 requires the flow diagram to report what was found and included.
- Identify the citing reviews. Use a citation index to find reviews that cite the missed study. Europe PMC supports citation and reference links alongside keyword and fielded searches, so it can surface citing records and their reference lists in one place. Record each citing review and the date you checked it.
- Search each citing review's reference list. Work through the reference list of every citing review and compare each entry against your eligibility criteria. Note the review, the reference entry, and your include/exclude decision for each candidate.
- Screen the newly found records. Apply the same eligibility criteria you used in the original search so the added studies are comparable. Log each record with its source (the citing review) and screening outcome.
- Add eligible studies to the screening log. Enter any newly eligible study with its identifier, the citing review that led you to it, and its inclusion status.
- Update the PRISMA flow counts. Revise the records-identified and records-included numbers to reflect the reference-list search, and describe the method in your search documentation so the flow diagram matches your reported methods.
Documenting the citing review for each added study keeps the gap-closing step traceable and lets readers see how the reference-list search changed the included set.