When a review needs updating
An SLR starts to date as soon as its search ends. New trials, new data cuts and new comparators appear, and an assessor will ask why they are missing. The usual triggers are a forthcoming submission, a new data cut from a pivotal trial, a new competitor, or a change in the scope an agency expects.
A recognised framework for the decision is the BMJ consensus checklist on when and how to update systematic reviews (Garner et al., 2016): is the question still current, is there new evidence or better methods, and would they change the findings? Read our insight: When does an HTA systematic review need updating?
What we deliver
- Audit of the existing review and its search strategies
- Re-run searches from the last search date, with de-duplication against previous results
- Dual screening, data extraction and risk-of-bias assessment of new studies
- Updated evidence tables, PRISMA flow diagram and report
- Updated network meta-analyses and indirect comparisons
- Living review set-up with scheduled searches tied to your submission calendar
Taking over another team's review
Many updates start with a review someone else built. We first check that the original protocol, searches and decisions can be reproduced. Where they cannot, we document the differences and agree how to handle them, so the update is robust and reproducible.
Plan updates around your launches
For products launching in several markets, a single review updated on a schedule is usually cheaper and more consistent than separate reviews. We plan update windows around JCA scoping, NICE and NCPE deadlines and expected data cuts. See systematic literature reviews and EU JCA dossiers.
What guidance says about updating
The Cochrane Handbook's chapter on updating a review bases the decision to update on two things: the continuing importance of the question to decision makers, and the availability of new data or new methods that would have a meaningful impact on the findings. Where changes to the methods are substantive, it encourages authors to write a complete, updated protocol. It also describes living systematic reviews, which adopt a continual updating process and are most likely to be appropriate for questions of high importance where new evidence is published frequently and is likely to change the findings.
Reporting is well supported. PRISMA 2020 includes flow diagram templates for updated reviews, so readers can see clearly which studies came from the previous review and which from the new searches.
For the EU joint clinical assessment, timing is explicit: the guidance on filling in the dossier template for medicinal products states that the search cut-off date should be a maximum of three months before submission of the dossier. Planning an update to land inside that window is part of planning the dossier.
Update, living review or new review?
| Option | Often suits | What it delivers |
|---|---|---|
| Targeted update | A single forthcoming submission with a stable question | New searches from the last search date, with the original methods carried forward |
| Update with revised scope | New comparators, populations or outcomes expected by an agency | An updated protocol, extended searches and documented changes to eligibility |
| Living systematic review | A long launch sequence, a fast-moving therapy area or repeated submissions | Scheduled searches and rapid incorporation of new evidence, ready for each deadline |
| New review | A new research question, or where a full systematic review is warranted | A fresh protocol and searches, with links to the earlier work where useful |
What a strong update looks like
- A clear statement of what changed: Search dates, sources, eligibility and methods compared with the previous version.
- Traceable study flow: A PRISMA 2020 flow diagram for updated reviews that separates previously included studies from new ones.
- Consistent decisions: New records screened and appraised on the same basis as the original, or with documented reasons for any change.
- Updated synthesis: Revised network meta-analyses reported alongside the previous results, so the effect of new evidence is visible.
- A view of what is coming: Ongoing studies and expected data cuts that may matter for the next submission.