Answer
Last Updated: Jun 30, 2017     Views: 4

This can be by using Mendeley. First you will need to set up a Mendeley account and download Mendeley Desktop. Once you have Mendeley Desktop installed follow these steps:

  1. Create a Parent folder in Mendeley with subfolders for each database
  2. Import citations into Database subfolders
  3. Select the Parent folder 
  4. Click on Tools then Check for Duplicates
  5. Merge any duplicates
  6. Select Parent folder and note number of items (find the number of items by clicking on one reference, the total number will be displayed at the bottom of the window)
  7. Select each subfolder and note number of items
  8. Add the total number of items in the subfolders
  9. Subtract the number from the Parent folder from the total of the subfolders – this is your number of duplicates.

In the image below, the Parent folder is PRISMA and the database subfolders are CINAHL, Cochrane and PubMed. At the bottom of the PRISMA folder contents, you can see there are 108 documents or references. 

Mendeley Folders and document list

The CINAHL folder contains 30 references, the Cochrane contains 18 and the PubMed folder has 82, The subfolder total is 130. With 108 references in the PRISMA folder, we can determine that there are 22 duplicates.