The HCUP Nationwide Inpatient Sample (NIS) featuring 2004 data has been released. The NIS is the largest all-payer inpatient care database in the United States, and is updated annually. It is available from 1988 to 2004, allowing analysis of trends over time.

The NIS is nationally representative of all short-term, non-Federal hospitals. It is based on a 20 percent stratified sample of hospitals that comprise 90 percent of all discharges in the United States. The data include all patients, regardless of payer -- including persons covered by Medicare, Medicaid, private insurance, and the uninsured. The data can be weighted to produce national estimates, allowing researchers and policy makers to use the NIS to identify, track, and analyze national trends in healthcare utilization, access, charges, quality, and outcomes. The vast size of the NIS enables analyses of rare conditions, such as congenital anomalies; uncommon treatments, such as organ transplantation; and special patient populations, such as the uninsured. Its size also allows the study of topics at both the national and regional levels. In addition, NIS data are standardized across years, to facilitate ease of use.

The 2004 NIS contains data from approximately 8 million hospital stays. It encompasses all discharge data from 1,004 hospitals in 37 states. For most states, the NIS includes hospital identifiers that permit linkages to the American Hospital Association's database and county identifiers that permit linkages to the Area Resource File from HRSA. The NIS contains clinical and resource use information included in a typical discharge abstract, with safeguards to protect the privacy of individual patients, physicians, and hospitals (as required by data sources).

As part of the Healthcare Cost and Utilization Project (HCUP) database family, the NIS is considered by health services researchers to be one of the most reliable and affordable databases for studying important healthcare topics.

The 2004 NIS can be purchased through the HCUP Central Distributor at HCUPDistributor@ahrq.gov, or via phone (toll free) at (866) 556-4287.