Well, some of this is actually from the ICD system, for billing purposes. In the US, that is. There are a whole host of different modifiers used for diagnosis codes--in full remission, severe, blah. That is what I suspect is going on here. No pdoc I have ever had or talked with uses these for anything other than trying to get paid. MD's in the US are paid according to the amount of time spent wiht the pt. and the perceived complexity of said visit.