Each database used should have the following information recorded:
See the section of this guide on 'Writing the review' for more detail reporting the details of your searches according to PRISMA.
It can also be useful to save your search strategies in the databases you use.
Systematic searching will require the collection of whole sets of results from databases to be reviewed. This part of the process needs to be planned as much as any of the other steps because the results will go through a number of screening stages to remove irrelevant and duplicate results. Using reference management software such as Endnote can help with organising and maintaining the search results. If using EndNote, the results for your systematic review project are best kept separate from your regular Endnote library. Set up a separate systematic review Endnote library. The Final steps section of this guide also contains some information on using EndNote for this process.
For information on accessing Endnote see our guide to EndNote referencing software.
| Database name and Platform | Process to export | Maximum number of results at a time |
|---|---|---|
| PubMed | * From the results screen select Send to Citation Manager * In Selection choose All results on this page * Select Create File * This will create a RIS file that will be sent to your EndNote Library |
10,000 |
| MEDLINE via Ovid | * At the beginning of the search results select the All box and the choose export option * In the Export Citation(s) choose the RIS Format * For Fields, select Citation, Abstract the select Export * The results will then be sent to EndNote as an RIS file * For over 3000 results rather than using the All box use the range box to select up to 3000 and export the search result in batches of following number ranges |
3000 |
| Embase.com (Elsevier) | * From the Results section select the Select number of items drop down that matches your search result number * Then select Export which will present a RIS export option and select Export * The next screen is a download screen. Choose Download. * The results will be sent to EndNote |
10,000 (500 without creating a personal account) |
| MEDLINE via EBSCOhost | *From the results screen select the Share drop down. *Choose the option below Export results which will state: *Email a link to download exported results (number range) *In the Export manager select E-mail a link to a file with citations in: Select the RIS option *Add your email address to the E-mail to option Select Send *A compressed RIS file of results will be sent to your email |
25,000 |
| Cochrane Library (Wiley) | * In the results sections click Select all & the Export selected citation(s) * Then select RIS(EndNote) & check the include abstract box * Click Download. * Records Will be sent to EndNote as a RIS file |
Unlimited |
| CINAHL via EBSCOhost | *From the results screen select the Share drop down. *Choose the option below Export results which will state: *Email a link to download exported results (number range) *In the Export manager select E-mail a link to a file with citations in: Select the RIS option *Add your email address to the E-mail to option Select Send *A compressed RIS file of results will be sent to your email |
25,000 |
| Web of Science (Clarivate) | * From the Search results select Export and choose EndNote desktop from the drop-down list * Select the records range. there is a maximum of 1000. *If your results are greater than 1000 you will have to choose batches. The first export is 1-1000, Then the next would be the next range until complete. E.g. 1001 - 1867 *Change record content to Full Record *Choose export *The results will be sent to your EndNote library as a RIS file |
1000 |
|
Scopus |
* From the results screen choose Select All *Choose Export at the top of the search results * Change the option to the RIS Format *Select Export *This will send the results to EndNote as a RIS file |
2,000 |
| Informit databases | * Cannot export set of records in Informit. Only one record at a time. * Open the record by selecting it via the Title * Select the Export Citations option * This will default to a citation window with the APA format. Change this via the drop down to EndNote * Use the download arrow below to export the file to EndNote |
1 |
Once all results have been retrieved via all of the database searches there will be a number of duplicate records which will need to removed. Some of the available deduplication tools require more manual intervention from the user, and some are more automatic. The various tools have been evaluated, and the more automatic tools such as Covidence are very good at not removing papers incorrectly. Whichever tool you use, any checking of the identified duplicates should be done very carefully to avoid removing potentially useful studies.
| Tool | How to deduplicate | Notes |
|---|---|---|
| Covidence | Covidence information on importing references | Covidence deduplicates automatically when you import references. You can then easily go on to screening within Covidence |
| Systematic Review Accelerator Deduplicator | SRA information on importing to the Deduplicator | The Systematic Review Accelerator is a suite of tools which can be used individually or in combination with each other. After using the Deduplicator you could then go on to use the SRA's Screenatron tool, or you could import your references into another tool for screening |
| Rayyan | Rayyan information on detecting duplicates | Note that on the free Rayyan plan, deduplication is a more manual process (you need to go through each duplicate, one by one). The auto resolver for duplicates is available only to subscribers |
| EndNote |
EndNote information on removing duplicates |
When deduplicating with EndNote, many librarians will use a multi-pass approach. This video (YouTube, 6m 59s) is a great overview of that process |
Systematic review searches may need to be re-run before the finalisation of the review. The Cochrane handbook recommends searches for all the relevant databases should be re-run prior to publication, if the initial search date is more than 12 months (preferably six months) from the intended publication date.