“Hopefully I have persuaded you that the change from ICD-9 codes to ICD-10 codes is big. But it may surprise you to learn it may be less intimidating than you think.
For example, you’re not going to have to be responsible for remembering thousands of ICD-10 codes. Your practice tends to deal with a subset of the possible diagnoses. “When you look at most practices, they deal with but a few hundred diagnosis and procedure codes,” says George Eleftheriades, chief technological officer of MD On-Line.”
Article
Carl Natale, ICD10 Watch, 18 July 2011

