Covidence will detect duplicate citations both within the file being uploaded as well as against all previous imports.

It checks on the following fields:

Title

   The titles must match exactly after basic normalisation, ignoring punctuation and special characters, but maintaining Unicode. 

   Where there is a non-English character, there is no conversion.

   For example, the citation:

       Dabigatran-related coagulopathy: When can we assume the effect has "worn off"?

   Would be normalised to:

       dabigatranrelatedcoagulopathywhencanweassumetheeffecthaswornoff

   As would the citation:

       Dabigatran related coagulopathy (When can we assume the effect has worn-off?)

   Meaning that it would be detected as a duplicate.

   However, the citation:

       Dabigatran-related coagulopathy

   Would not be detected as a duplicate.

Year

   The four digit field for year must match exactly.

Volume

   The volume must match exactly, ignoring special characters, such as brackets.

Author

   The authors must be sufficiently similar in order to be detected as a duplicate. They do not have to be exact matches.