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Duplicate Citations

Covidence does de-duplicate citations as they are imported from various databases, but they tend to err on the side of caution and miss many duplicates.  As they say on their webpage: "Because Covidence uses a very strict de-duplication method, it has the benefit of rarely, if ever, taking out duplicates mistakenly, but can have the side effect of missing some that a reference manager program may have been able to detect." 

Unfortunately it is not possible to add duplicates to the set of duplicates Covidence identified upon import.  As you screen the title and abstract, you have a few options for dealing with duplicates:

  • If you don't need an accurate count of duplicates (for example, for a PRISMA chart for a systematic review, smply vote NO on the duplicates.  This will simply prevent the duplicated citation from moving on to the next stage.  The number of duplicates identified by Covidence in import process will not change, but this only matters if you need accurate duplicate numbers.
  • If you do need an accurate count of duplicates for a PRISMA chart, try these steps: 
    • vote NO on duplicates
    • tag the duplicate citation.  The first time you do this, create a tag that says "Duplicate."  To do this, you should be at/in the citation that is a duplicate.  Click the word Tag.  Type in your term (ie Duplicate) and click "Create New."  Then click the newly created box so that the tag is applied.  Check to make sure the tag is applied by scanning to the botom of the citation.  The word "Duplicate" should show up in light grey with a dotted border.  Don't forget to vote NO on the duplicate!
    • Once you have created the tag for Duplicate, when you come across a duplicate, simply click the word Tag, then check the box for Duplicate and hit enter so the box itself turns a slightly darker color.  The first few times you do this, it is recommended to check to make sure the tag is applied by scanning to the botom of the citation.  The word "Duplicate" should show up in light grey with a dotted border.  Don't forget to vote NO on the duplicate!
    • When you are done with the Title/Abstract screening process, you can search the tags for the word Duplicate, count them up, and remember to manually add that number to the PRISMA chart that Covidence provides.  To do this, make sure you are in the Title/Abstract screening area and look for the ones you deemed "Irrelevant" by voting "NO" on them.  Click All, then type the word Duplicate in the search box, then hit Filter.  Covidence will scan all citations in this area and give you a number of items that have been tagged as Duplicate.  MAKE A NOTE OF THIS NUMBER!  You will have to manually change the number of duplicates in the PRISMA chart that Covidence provides (you'll have to add this number to the one they have for an accurate total).

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