Highly doubtful that the police or paramedics will look into your PSK, or even know what it is assuming a converted Altoids tin, etc. Never-the-less, I have personal contact info in my PSK. And in my wallet. Nothing sensitive like SSN. Only contact names and phone numbers, my home address, allergies - stuff like that.

No hospital in their right mind would give you blood based on a blood type you wrote down in your PSK. That info would be ignored. Now telling them NOT to give you something - specify things you are allergic to - THAT info should be heeded, provided were they able to find it in you PSK in the first place.