Evidence that using upper-case 'O' and lower-case 'l' in ICD-10-CM codes is a big mistake

In a study of the accuracy of ICD-10-CM coding, a key "lesson learned" is that:  Coders often confused the number "0" (zero) with the letter "0", and the number "1" (one) with the letter "l".

This "lesson learned" should have been fully expected.  Dr. Vergil Slee and colleagues knew this problem would occur over 13 years ago in their book The Endangered Medical Record.

ICD-10-CM is a boondoggle.  We should not switch.