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Table 2 Refinement of the pseudonymisation tool

From: Using electronic patient records to assess the effect of a complex antenatal intervention in a cluster randomised controlled trial—data management experience from the DESiGN Trial team

Test round Maternal data components used Study ID format Study ID length Duplicates
1st DOB, DOD, NHS number ##########
e.g.1234567890
10 18,382/100000
2nd DOB, DOD, NHS number ############
e.g. 123456789012
12 18,382/100000
3rd DOB, DOD, NHS number, check digit ###############XXX
e.g. 123456789012345ABC
18 21/100000
4th DOB, NHS number, check digit, random component with seed ###################X
e.g. 1234567891234567891A
20 0/100000
  1. DOB date of birth, DOD date of delivery (of neonate), ID identifier, NHS National Health service