Clinical Classifications Software (CCS) consists of over 260 diagnosis categories. All ICD-9-CM diagnosis codes are classified.
DXCCSn is coded as follows:
- 1 to 259 if the diagnosis code (DXn) is valid by the HCUP criteria and not an External Causes of Injury (E-code). The HCUP criteria for diagnosis validation allows a year window (six months before and six months after) around the official ICD-9-CM coding changes (usually October 1), for anticipation of or lags in response to official ICD-9-CM coding changes.
- 2601-2621 if the diagnosis code (DXn) is a valid E-code by the HCUP criteria.
- DXCCSn is missing (.), if there is no diagnosis code (DXn = " ").
- DXCCSn is set to invalid (.A), if the diagnosis code (DXn) is invalid by the HCUP criteria (EDX02).
- DXCCSn is set to inconsistent (.C), if the diagnosis code (DXn) is inconsistent with age (EAGE04 and EAGE05) or sex of the patient (EDX03).
For data beginning in the fourth quarter of 2015, the CCS is stored in the data element I10_DXCCSn to indicate the implementation of the ICD-10-CM/PCS coding system. In HCUP databases before 1998, this data element is called DCCHPRn.
Labels for CCS categories are provided as an ASCII file in HCUP Tools: Labels and Formats.
Formats to label CCS categories are documented in HCUP Tools: Labels and Formats. A format is also available to map CCS codes into a few broad classes of conditions based on ICD-9-CM chapters.