Healthcare Common Procedure Coding System (HCPCS) Level I (CPT) and Level II procedure codes are frequently used on outpatient bills to report procedures and services performed by physicians, nonphysician practitioners, hospitals, laboratories, and outpatient facilities. The procedures code data elements (CPTn) are provided by the data source. Null values are set to blank. HCPCS codes are compared to a list of codes valid for the discharge date. Anticipation of or lags in response to official coding changes are permitted for discharges occurring within a window of time (six months before and six months after). HCUP validates Level I (numeric) and Level II codes (A0000-V9999) but does not validate the Level III codes (W0000-Z9999). If the HCPCS procedure code is not on the list of valid codes, CPTn is set to invalid.

If the HCPCS procedure code is inconsistent with sex (ECPT02), CPTn is set to inconsistent. We discontinued age edits for HCPCS level I (CPT codes) beginning with data year 2011 and we discontinued age edits for all other HCPCS codes beginning in 2015. The corresponding CPTCCSn, sex, and age values (prior to 2015) were also set to inconsistent.

The original value of the primary CPT-4/HCPCS procedure (CPT1), whether blank or coded, is retained in the first position of the procedure vector. Starting at the first secondary procedure (CPT2), the procedures are shifted during HCUP processing to eliminate blank secondary procedures. For example, if CPT2 and CPT4 contain nonmissing procedures and CPT3 is blank, then the value of CPT4 is shifted into CPT3. Secondary procedures are never shifted into the primary position (CPT1).