The current ICD-9 coding system no longer fits with 21st Century healthcare information needs and transitioning to ICD-10 will improve our ability to track and respond to national and international public health threats (like the SARS and Bird Flu threat some years ago).
There are several structural differences between ICD-9-CM codes and ICD-10 codes. ICD-9-CM (VOLS. 1 & 2) has a field length of 3-5 characters whereas ICD-10-CM has 3-7 characters.
Currently, there are about 14,000 codes in ICD-9CM and approximately 69,000 codes in ICD-10 CM. ICD-9 has Digit 1 which is alpha or numeric and Digits 2-5 which are numeric. ICD-10 has digit 1 which is alpha, digit 2 which is numeric and digits 3-7 which could be alpha or numeric. The available space for new codes is limited in ICD-9CM whereas in ICD-10 CM it is more flexible.
As a reminder to everyone that ICD-10 has been out for about 20 years for the rest of the world other than the US so we would put now be on an even footing with our global counterparts. Something to think about while we move forward in this transition.