PRSYS indicates the coding system for the procedures:

• Almost all HCUP inpatient stays use ICD-9-CM procedure codes (PRSYS = 1)
• If Physicians' Current Procedural Terminology (CPT) or HCFA Common Procedure Coding System (HCPCS) procedure codes are indicated (PRSYS = 2 or 3), then the procedure codes are set to missing (PRn = blank). CPT and HCPCS procedure codes could not be retained in the HCUP data because they are 5 characters, and the HCUP procedure fields (PRn) are 4 characters in length.
• If the procedure coding system was not specified by the data source, then PRSYS is missing (PRSYS =l .)

The data element PRSYS was discontinued in 1998.

The reporting and handling of CPT and HCPCS procedure codes varies by year:

• Prior to 1995, Pennsylvania supplied only ICD-9-CM procedure codes (PRSYS = 1).
• From 1995-1996, Pennsylvania supplied a mixture of ICD-9-CM, CPT and HCPCS codes. PRSYS which identifies the procedure coding system was assigned based on the value reported by the data source (PRSYS = 1, 2, or 3).
• In 1997, Pennsylvania source documentation indicated that all procedure codes were ICD-9-CM codes (PRSYS = 1).. Any procedure codes that were suspected of being CPT or HCPCS codes were masked during HCUP processing.
• Beginning in 1998, Pennsylvania supplied only ICD-9-CM procedure codes.

See the Pennsylvania note on procedures (PRn) for more specific details.

Prior to 1995, CPT and HCPCS procedure codes were not included in the Pennsylvania data.

From 1995-1996, the number of discharges for which the procedure coding system indicated that the procedures were CPT or HCPCS (PRSYS = 2 or 3) follows:

• NIS, Release 4 (1995 data) has no records.
• NIS, Release 5 (1996 data) has 1,711 records.

In 1997, CPT and HCPCS procedure codes do not occur in the data supplied by Pennsylvania.