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).

Labels

Labels for CCS categories are provided as an ASCII file in HCUP Tools: Labels and Formats.

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.

Due to an error in HCUP processing, about 9,000 records in the 1999 MA SID have an incorrect value of DXCCSn. The value 260 was assigned instead of the value of 2621 for E-codes in the range of E8490-E8499.