Clinical Classifications Software (CCS) consists of 231 procedure categories. All ICD-9-CM procedure codes are classified.

PRCCSn is coded as follows:

• 1 to 231 if the procedure code (PRn) is valid by the HCUP criteria. The HCUP criteria for procedure 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.
• PRCCSn is missing (.), if there is no procedure code (PRn = " ").
• PRCCSn is set to invalid (.A), if the procedure code (PRn) is invalid by the HCUP criteria (EPR02).
• PRCCSn is set to inconsistent (.C), if the procedure code (PRn) is inconsistent with age (EAGE05) or sex of the patient (EPR03).

In HCUP databases before 1998, these data elements are called PCCHPRn.

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.