Choosing an ICD-9 code (instead of just making up a diagnosis) has the advantage of populating the Problem List in the Summary Sheet, which also allows you to quickly fill your Assessment field at your next encounter.
I started out just typing in a diagnosis, but switched to ICD-9 codes, because I thought it would be good for me to get acquainted with the codes in case I ever did my own billing.
Now, there is one disadvantage of using an ICD-9 code as a diagnosis, in that ICD-9 codes are billing codes and they force you to pigeonhole your patients.
This degrades the transmission of medical information.
For example, there is no ICD-9 code for "Brittle Diabetic", yet that phrase speaks volumes to the next physician who sees your patient.
