This section describes the original data files obtained from data organizations in participating states and used to create the HCUP outpatient databases. Information about the source of the original data files, the types of hospitals included in those files, the records excluded during HCUP processing, and other pertinent information to understand the composition of these files are presented after the Overview in state-specific sections.

Overview of HCUP Outpatient Databases

Prior to data year 2003, HCUP Partners were asked to provide HCUP with separate ambulatory surgery (AS) and emergency department (ED) source files, if possible, and a combined outpatient file with records flagged by type, as an alternative. Records identified as AS were included in the SASD. Records identified as ED were included in the SEDD. Investigation of these data files revealed that different data sources often defined AS and ED records slightly differently. In addition, a number of the AS and ED source files included other types of outpatient records such as chemotherapy, mammograms, and observation stays. The section "Selection of Records Prior to 2003" includes state-specific information on the inclusion of records in the SASD and/or SEDD prior to 2003.

Starting with the recreated, version 2, 2003 data and data year 2004, HCUP used the state-defined indication of AS and ED records for inclusion in the SASD and SEDD. Records identified by the state as AS were included in the SASD. Records identified by the state as ED were included in the SEDD. Three HCUP data elements (STATE_AS for AS services, STATE_ED for ED services, and STATE_OS for observation services) include information on the source-defined record type.

Data elements derived during HCUP data processing indicate that there is evidence on the HCUP record to indicate an AS, ED, or observation stay (OS) service. These three data elements (HCUP_AS for AS services, HCUP_ED for ED services, and HCUP_OS for observation services) will be on the SASD and SEDD files.

In contrast to other years, all ED records are placed in the SEDD. This includes

• Records identified by the state as ED
• Records with evidence of ED services (HCUP ED › 0).

This change means that some ED records will be included in BOTH the SASD and SEDD. Therefore, all outpatient ED records are available in the SEDD. If the HCUP Partner has indicated that the record is an ambulatory surgery record, but there is evidence of ED services on the HCUP records (i.e., ED charges or revenue codes), then the record is placed in both the SASD and SEDD.

In the first version of data year 2003, the allocation of records into the SASD and SEDD was handled differently. HCUP applied uniform criteria based on information available on the HCUP file for the selection of AS records for the SASD and ED records for the SEDD.

For the SASD, the criteria for identifying ambulatory surgery records include the following:

• Presence of at least one ICD-9-CM or CPT-4 procedure in the following ranges:


ICD-9-CM procedure codes 00.50-86.99 or 88.40-88.59

CPT-4 procedure codes 10040-69999, 70496, 70498, 70544-70549, 71275, 71555, 72159, 72191, 72198, 73206, 73225, 73580, 73706, 73725, 74175, 74185, 75600-75790, 75893-75898, 75952-75954, 75992-75996, 78445, 92287, 92975, 92992-92993, 93501-93581.

• Length of stay of 0 or 1 days, if this information is available.

For the SEDD, the criteria for identifying ED records vary across states because of the differing availability of necessary data elements. We use one or more of these three criteria:

• A revenue center code in the range 450-459, indicating ED charges; or
• A CPT procedure code in the range 99281-99285, indicating an ED visit; or
• A positive emergency room charge, if revenue center codes are not available

If a record fits both the AS and ED criteria, the record was included in the SASD with an indication of ED services (HCUP variable EDflag › 0) with one exception. If a data source provides only ED data to HCUP, then the combination AS/ED records were placed in the SEDD file with an indication of AS services (HCUP variable ASflag › 0).

For all states, records that fit neither the AS nor ED screen are excluded from the SASD and SEDD. Records excluded from the SASD and SEDD were placed in the State Unused Files (STUF). It became apparent in evaluating the records excluded from the SASD and SEDD that in some cases the HCUP Partners had more information available to them and, therefore, were better able to identify AS and ED records.

If the data elements EDflag or ASflag are on the 2003 data file, then the HCUP file had records excluded and placed in the STUF file. If the data elements HCUP_AS, HCUP_ED, or HCUP_OS are on the 2003 file, then records were not excluded and placed in the STUF file.

For a description of the file composition for one or multiple States, check the corresponding boxes below and then click the "View File Composition" button.