The Agency for Healthcare Research and Quality (AHRQ) is pleased to announce the release of the Healthcare Cost and Utilization Project (HCUP) Nationwide Inpatient Sample (NIS) featuring 2007 data. The NIS is the largest all-payer inpatient care database in the United States and is updated annually. It is available from 1988 to 2007, allowing analysis of trends over time.

The NIS is nationally representative of all short-term, non-Federal hospitals in the United States. It approximates a 20 percent stratified sample of hospitals in the U.S. and is drawn from the HCUP State Inpatient Databases (SID), which include 90 percent of all discharges in the United States. The NIS includes all patients from each sampled hospital, 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 health care utilization, access, charges, quality, and outcomes. The vast size of the NIS enables analyses of infrequent conditions, such as rare cancers; uncommon treatments, such as organ transplantation; and special patient populations, like the uninsured. Its size also allows for the study of topics at both national and regional levels. In addition, NIS data are standardized across years to facilitate ease of use.

The 2007 NIS contains data from over 8 million hospital stays, and encompasses all discharge data from more than 1,000 hospitals in 40 states. For most hospitals, the NIS includes identifiers that allow linkages to the American Hospital Association's Annual Survey Database, and county identifiers that permit linkages to the Area Resource File (ARF) from the Health Resources and Services Administration (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 HCUP database family, the NIS is considered by health services researchers to be one of the most reliable and affordable databases for studying important health care topics.

The 2007 NIS can be purchased through the HCUP Central Distributor. Some 2007 NIS data are available in HCUPnet, a free online query system. More information about the NIS and other HCUP products can be found on the HCUP-US Website.