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Systematic Reviews: Updating a search

Overview of systematic review methodology and key strategies for searching and reporting to the Cochrane Collaboration's Gold Standard

Updating a search

Sometimes you may need to update database searches. This may be because:

  • you have taken leave from working on your review
    The Cochrane Handbook states that 'The search must be rerun close to publication, if the initial search date is more than 12 months (preferably six months) from the intended publication date, and the results screened for potentially eligible studies' - 4.4.10 Timing of searches. Journals may request that searches be re-run prior to publication, if months have passed since submission
  • you are updating a previously published review
    Reviews may be updated for a range of reasons, such as flaws in the original conduct, or publication of new studies likely to result in changes to the conclusions

In updating the search, you will be trying to find new resources that have been added to databases since you last ran your search. This will include newly published material, but may also include records for older material that have recently been added to the databases.

This page will show you a few methods of updating a search in various databases. You aim is to collect newly available records without needing to screen all your records again. If you haven't undertaken screening yet, you can simply re-run your searches in your chosen databases.

Note: if it has been a considerable amount of time since you developed your search strategy, databases or subject headings may have been modified. Check for an changes to the thesaurus terms, available limits, etc.

MeSH is updated annually. New terms are added and some terms are changed. Older records are not retrospectively re-indexed with new headings. For example, Decision making, shared was added in 2020; to locate material on this topic from the last decade, both Decision making and Decision making, shared would need to be used

Finding new records

A quick way to find new material is to re-run the searches limiting by publication date range. This is not guaranteed to find all material added to a database since the last time the search was run as it wil miss any records added retrospectively (e.g. to correct an error in indexing, or because a database is expanding its coverage). 

To find all records added to a database since you last ran the search, you may be able to search on a specific field in the records that specifies when they were created or added to the database (note that this is not the publication date) and limit to a specific range. Unfortunately, not all databases allow you to search by 'create date'.

A range of possible approaches for key databases are outlined in the table below.

Database (platform)

Details

Example

MEDLINE (via Ovid)

limit x to dt=YYYYMMDD-YYYYMMDD

x is the number of the final row of your search. Date format is YYYYMMDD

Create date (.dt.) in Ovid MEDLINE is the date when the record was created

limit 10 to dt=20171115-20201009

Limits line 10 to between 15th Nov. 2017-9th Oct. 2020
Embase (via Ovid)

limit x to dc=YYYYMMDD-YYYYMMDD

x is the number of the final row of your search. Date format is YYYYMMDD

.dc is date created

limit 10 to dc=20171115-20201009

Limits line 10 to between 15th Nov. 2017-9th Oct. 2020
PsycINFO (via Ovid)

limit x to up=YYYYMMDD-YYYYMMDD

‘The Update Code (UP) field appears in all records and contains the date the record was released into the database. It is sometimes referred to as "Entry Month."’

limit 10 to up=20171115-20201009

Limits line 10 to between 15th Nov. 2017-9th Oct. 2020
JBI (via Ovid) No relevant field available. Re-run whole search and use de-duplicating in EndNote method OR base on publication date

limit 10 to yr="2017 - 2020"

Limits line 10 to between 2017 and 2020
Scopus

ORIG-LOAD-DATE AFT YYYYMMDD

use AND to join this line to the last line of your search

AND ORIG-LOAD-DATE AFT 20171114

Limits search results to records added after 14th Nov. 2017
Web of Science

Index Date can be entered in YYYY-MM-DD format. Use the dedicated field for this function - cannot enter code directly into search

Index Date: 2017-11-15 to 2020-10-09

Limits results to between 15th Nov. 2017-9th Oct. 2020

Another option is more complex, using multiple EndNote libraries to create de-duplicated sets of records for each database. This won’t be perfect as some duplicates may not be detected where records have been revised/updated and some records in the original set may have been subsequently withdrawn.

To use this method, you will need the original set of results in order to create an updated set of results:

  1. Start with two libraries – one with your original results from one database (Database A) and an empty library.
  2. De-duplicate the original library from Database A, in case there are existing duplicates.
  3. Run your original search in Database A again (with no date limits).
  4. Export this to the empty EndNote Library and de-duplicate the records.
  5. Copy both of those sets to a third EndNote library to create a combined set of old and new results.
  6. De-duplicate the third (combined) library in EndNote. Delete all records in the 'Duplicates' group. Whatever remains is the new material to screen.

You will need to repeat this process for each database, and update your PRISMA to include the numbers from the new searches.

Note: This approach is detailed further in Bramer and Bain’s Updating search strategies for systematic reviews using EndNoteMcGill Library also has a set of instructions on how to use this method.

Guidelines and standards


Other standards

Setting up database alerts

While working on your systematic review, you can set up alerts for your searches in different databases to receive email notifications of new records added.

Further reading