unmemorable numeric string as foreign key
asked of people and typed in to recall records.
The new NHS Number is a 9 digit string + modulo 11 check digit.
It isn't very useful for quick selection from a list. Feel free to work on that.
Most of my patients can have their record called up with 2 letters of surname and 2 of forename.
The NHS number has some odd rules baked in - gender is locked for instance so have a gender change and your identity fails. Clearly this is a business rule somewhere since the number doesn't encode the gender of indeed anything else - unlike the CHI string.
Neither is even slightly useful for effective pseudonymisation.
But one of the more obvious reasons it lsaks in slowly is that these systems are not mostly new ones.