New Jersey Department of Health and Senior Services provides one source file to HCUP that contains a mixture of inpatient and ambulatory surgery (AS) records from acute care hospitals. The file does not distinguish record types. During HCUP data processing, AS records are identified by one of the two following criteria:

• Admission and discharge dates are the same and there is a charge for same day surgery
• Admission and discharge dates are the same, there is a charge for the operating and recovery room, the patient is discharged alive to a destination other than a short-term general hospital, and the patient is not discharged against medical advice.

Beginning in 1999, records with a discharge disposition of "still a patient" were excluded from the HCUP ambulatory surgery files. Prior to 1999, this type of record was not included in the source data files.

Beginning in 2005, the definition of ambulatory surgery records was based on the UB-92 bill type - the first two digits must be "13" (BillType = 13x) to indicate hospital outpatient services. Inpatient records must have the first two digits of "11" or "12" (BillType = 11x or BillType = 12x) to indicate hospital inpatient services. Prior to 2005, the definition of ambulatory surgery records supplied by New Jersey was:

• Same day stay (ADATE = DDATE)
• Non-zero charges to operating room (CHG24 > 0) or same day surgery (CHG32 > 0), and
• Discharged to home (DISP = 1).

Using the standard HCUP criteria for assigning records to the 2003 SASD, the source records are separated as follows:

• 97% of source records are assigned to the SASD
• 3% of the records were excluded.

Identifying Freestanding Facilities. Starting in 1998, the data element FREESTANDING identifies hospital-based and freestanding ambulatory surgery facilities. Prior to 1998, there are two identifiers on the SASD that allow a researcher to identify hospital-based and freestanding ambulatory surgery centers.

• DSHOSPID is the facility identifier provided by the data source.
• AHAID is the facility identifier used by the American Hospital Association.

1997 New Jersey SASD. There are 94 unique DSHOSPID values in the 1997 NJ SASD. All should be considered hospital-based facilities.