The diagnosis code on the claim. There are up to 12 diagnosis codes on the IP header claim, up to five (5) for LT, and up to two (2) for OT. The lower the number, the more important the diagnosis in the patient treatment/billing (i.e., DGNS_CD_1 is considered the primary diagnosis).
The code is either an ICD-9 or an ICD-10-CM code, depending on the date. For ICD-9 diagnosis codes, this is a 3-5 digit numeric or alpha/numeric value; it can include leading zeros. In October 1, 2015 the conversion from the 9th version of the International Classification of Diseases (ICD-9-CM) to version 10 (ICD-10-CM) occurred. The Diagnosis Version Code associated with each of the diagnosis codes, indicates whether the version was ICD9 or 10 (refer to the DGNS_VRSN_CD_1-12 fields).
SOURCE: T-MSIS Analytic File (TAF) Claims