[LatteLazy]

Because you can do something very similar with combos of other fields in the data. That's the problem here: no one knows what combination of details deannonimise a record. So what do you remove, all of them? So the claim it is anonymous is BS. And once the records are out there, there is no way to get them back...

Edit: as an example, I was in a car accident as a 17 year old and broke my jaw. If you Google my name and the location you'll see the news article. I was the only person treated at the local hospital for a broken jaw that day. You just deannonimised me.

Or go again: I'm the only person from my town who went to my university in the year I went. Just look for someone treated in <home area> term time and <uni medical clinic> term time 2002-2008.