The HCUP New York inpatient files were constructed from the New York State Department of Health's Statewide Planning and Research Cooperative System (SPARCS) Master File.

For 1988-1993, New York supplied their Master File which consists of Discharge Data Abstracts (DDAs) matched to Uniform Billing Forms (UBFs) for inpatient stays. New York created the Master File by matching DDAs and UBFs based on Permanent Facility Identifier, Medical Record Number, Admitting Number, Admit Date, and Discharge Date. If the DDA and UBF records matched, the information from the DDA and UBF was included in the Master File. If there was no match, the information from the DDA was included in the Master File. Due to an administrative change in the collection of billing records for 1989, a large percentage of the DDAs could not be matched to a UBF. When there was no match, charge information, which would have come from the UBF, is missing. The match rate improves over time and stabilizes after 1991. The percentage of DDA records that have a matching UBF record in the Master File are as follows:

Beginning in 1994, hospitals submitted discharge records to New York in a new format, using Universal Data Set (UDS) specifications. This format combines the old UBF and DDA data into a single submission record. In these years, New York supplied records for HCUP that contain complete discharge and uniform billing data corresponding to the "matched" records in earlier years.

The New York files contain inpatient discharges from acute care hospitals in the state, excluding long-term care units of short-term hospitals and Federal hospitals.

Not all hospitals report a full calendar year of data. Some hospitals close during the year; other hospitals have technical problems that prevent them from reporting a full year.

The documentation supplied by New York indicates that the data include stays in detoxification (alcohol and drug abuse), alcohol rehabilitation, mental retardation, mental rehabilitation, rehabilitation, alternate level of care, and psychiatric (acute and long term) units within community hospitals. Records for these different types of care cannot be identified from the data elements available in the HCUP New York inpatient data.

The following New York records were excluded from the HCUP inpatient database:

• For all years, interim records for patients who had not been discharged.
• For 1988-1992, records with a transaction code indicating "Deletion of a Record Previously Accepted" were excluded. These records were incorrect versions of accurate records included elsewhere in the SPARCS files. This was not a problem in subsequent years' data.
• For 1988-1993, Uniform Billing Forms (UBFs) that could not be matched to Discharge Data Abstracts (DDAs) were excluded. Matched DDA and UBF records and unmatched DDA records (without charges) were retained in the data.
• Beginning in 1994, records with a discharge disposition of "still a patient."
• Beginning in 1998, records with a discharge disposition of "admitted to this hospital."