The diagnosis code identifying the diagnosis, condition, problem or other reason for the admission/encounter/visit shown in the medical record to be chiefly responsible for the services provided.
This data is also redundantly stored as the first occurrence of the diagnosis code (variable called ICD_DGNS_CD1).
Starting in 2011, with version J of the NCH claim layout, institutional claims can have up to 25 diagnosis codes (previously only 11 were accommodated), and the noninstitutional claims can have up to 12 diagnosis codes (previously only up to 8).
Effective with Version 'J', this field has been expanded from 5 bytes to 7 bytes to accommodate ICD-10.
On 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.