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AHCPR expands public access to two hospital databases

As part of the Agency's continuing effort to facilitate public use of AHCPR databases, we have enhanced access to two databases on hospital stays. Both databases are components of the Healthcare Cost and Utilization Project (HCUP), which is a family of administrative, longitudinal databases and related software developed and maintained by AHCPR in partnership with States and private data organizations.

HCUP data are used for research on hospital utilization, access, charges, quality, and outcomes. The data can be used to describe patterns of care for both common and uncommon diseases, analyze hospital procedures, and study the care of particular populations, including minorities, children, women, the elderly, and the uninsured. Researchers and policymakers use HCUP data to identify, track, analyze, and compare trends at the national, regional, and State levels.

The first set of data, the State Inpatient Database (SID), is a collection of individual data sets from 19 participating States; each data set contains the universe of that State's hospital discharge abstracts. The data have been translated into a uniform format to facilitate cross-State comparisons. SID represents more than half of all U.S. hospital discharges, and State participation is growing.

The second database, the Nationwide Inpatient Sample (NIS), is a stratified probability sample of hospitals drawn from the SID. The NIS is designed to approximate a 20 percent sample of U.S. community hospitals, including roughly 6.5 million discharges from about 900 hospitals. NIS is the largest all-payer inpatient database in the United States, and data are now available from 1988 to 1996.

In addition to purchasing the NIS database, an option that has been in place for the last 5 years, users can now access selected 1996 NIS data in an interactive format on HCUPnet. HCUPnet accommodates real-time queries of the NIS database, providing information on number of discharges, length of stay, charges, and in-hospital mortality for diagnoses and procedures by selected patient and hospital characteristics.

The SID and NIS contain over 100 variables, including principal and secondary diagnoses and procedures; admission and discharge status; patient demographics; expected payment source; total charges; length of stay; hospital characteristics; and hospital and county identifiers that permit linkages to other databases.

The NIS and SID data sets can be run on desktop computers with a CD-ROM reader; NIS and SID are in ASCII format for ease of use with various off-the-shelf software products, including SAS and SPSS. Programs are provided for converting ASCII files. The NIS data set includes full documentation in Adobe® Acrobat® and weights for producing national and regional estimates.

NIS may be purchased from the National Technical Information Service. Information on purchasing the SID will be available on the AHCPR Web site later this summer. Questions about HCUP products may be sent via E-mail to

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