Nationwide Inpatient Sample (NIS) Release 3: Fact Sheet

Sponsored by the Agency for Health Care Policy and Research (AHCPR), the Healthcare Cost and Utilization Project (HCUP) includes two databases for health services research, currently providing 8 years of data (1988-95). Both databases contain patient-level information for inpatient hospital stays in a uniform format while protecting privacy. The Nationwide Inpatient Sample (NIS) includes inpatient data from a national sample of about 900 hospitals. The State Inpatient Database (SID) covers inpatient care in community hospitals in 19 States that represent more than half of all U.S. hospital discharges. Database releases result from a Federal-State-industry partnership sponsored by AHCPR to build a multi-State health care data system.

Background

Nationwide Inpatient Sample (NIS) Release 3 comprises a set of six CD-ROMs containing key data on the hospital inpatient care of millions of Americans in 1994. NIS Release 3 is a product of the Healthcare Cost and Utilization Project (HCUP-3), a Federal-State-industry partnership sponsored by the Agency for Health Care Policy and Research (AHCPR). NIS is one component of the powerful, multistate health care data system for research, market analysis, and other purposes that has been developed under HCUP-3. (Select to access the HCUP Overview.)

NIS Release 3 is designed to approximate a 20-percent sample of U.S. community hospitals. The NIS sample is a stratified probability sample of hospitals in the participating States. The database includes all discharges from the selected hospitals. It contains weights to produce national estimates.

States in NIS Release 3

Arizona       Massachusetts
California    New Jersey
Colorado      New York
Connecticut   Oregon
Florida       Pennsylvania
Illinois      South Carolina
Iowa          Washington
Kansas        Wisconsin
Maryland

Main features of NIS Release 3

Some of the main features of NIS Release 3 follow:

The most powerful dataset of its type readily available in the United States.
Contains data on 6.4 million inpatient stays in more than 900 hospitals in 17 geographically dispersed States.
Includes more than 100 clinical and resource use variables.
Includes charges and the expected primary payer (private health insurance, Medicare, Medicaid, out-of-pocket, and other sources).
Captures uncommon conditions and procedures, such as congenital anomalies and organ transplantation.
Has weights to produce national estimates.
Includes hospital identifiers to link with the Annual Survey of Hospitals of the American Hospital Association for information on hospital services, personnel, and other data (when permitted by data sources).
Can be linked to county-level information on the availability of medical personnel and services in the Area Resource File of the Bureau of Health Professions.
Protects the privacy of individual patients and physicians.
Can be run on desktop computers.

Uses of NIS data

NIS data are invaluable for many types of research involving hospital inpatient care. For example, NIS Release 3 can be used to:

Compare services and costs of managed care organizations, hospital chains, and individual facilities with national data.
Determine the costs of treating specific conditions.
Study the use and costs of hospital services.
Analyze use of inpatient procedures.
Examine medical treatment variation.
Aid research on medical treatment outcomes and quality of care.
Prioritize strategies for product development.
Study medical technology diffusion.
Project the impact of proposed legislation on hospital cost containment.
Examine health care cost inflation and hospital financial distress.

NIS Release 3 variables include:

Hospital identifiers.
Patient demographic characteristics.
Diagnoses and procedures.
Admission and discharge status.
Length of stay.
Day on which principal procedure is performed.
Expected pay source.
Total charges.
Hospital characteristics: ownership, bedsize, teaching status.

NIS data clients

Users of previously released HCUP-3 data have included health services researchers, health insurance companies, managed care organizations, hospitals, health care consultants, pharmaceutical manufacturers, medical device manufacturers, trade associations, special-interest groups, State government agencies, and universities.

How To Order HCUP NIS Data

NIS users are required to sign agreements to use the database for research and statistical purposes only. By signing the Data Use Agreement, users agree not to use the data to identify individuals or to identify institutions in published or otherwise disseminated materials. A signed agreement (original or facsimile) must be on file at the National Technical Information Service (NTIS), which distributes NIS for AHCPR, before data can be shipped.

To order NIS data:

Call NTIS at 800-553-6847.
NTIS will fax you the Data Use Agreement. Read it. Sign it.
Return the Data Use Agreement to NTIS.

HCUP Nationwide Inpatient Sample (NIS) includes:

Data in ASCII format.
NIS Documentation in Adobe® Acrobat® Portable Document Format (PDF).
NIS Tools (record layouts and programs to assist SAS and SPSS users).

Select to access specific information about the following releases from the Web site of the National Technical Information Service, including online ordering:

Release 4, 1995 data (PB 98-500440)
$160 for the 1-year, 6-CD set. (Select to access online fact sheet.)

Release 3, 1994 data (PB 97-500433)
$160 for the 1-year, 6-CD set.

Release 2, 1993 data (PB 96-501325)
$160 for the 1-year, 6-CD set.

Release 1, 1988-1992 data (PB 95-503710)
$300 for the 5-year, 26-CD set.

You may also obtain a data use agreement and order HCUP-3 Nationwide Inpatient Sample Release 3 (Order number: PB 97-500433) by contacting:

National Technical Information Service
5285 Port Royal Road
Springfield, VA 22161
Telephone: (703) 487-4650 or 800-553-6847

Cost: $160 plus handling for a set of 6 CD-ROMs in ASCII format. Includes Adobe® Acrobat® (Windows® Reader™ provided) and NIS Tools (to assist SAS and SPSS users).

Other AHCPR hospital data products

In addition to NIS data releases, AHCPR has produced a variety of CD-ROMs, data tapes, and publications to facilitate research and inform the public about hospital care in the United States. These include:

State Inpatient Database (SID)—Uniform data on hospital stays in 11 States (1988-94). SID covers almost 50 percent of all U.S. hospital discharges. State governments and hospital associations that provided the data control the distribution of the data.

Clinical Classifications for Health Policy Research (CCHPR)—Software to classify diagnosis and procedure codes into categories for reporting purposes.

Diagnosis and Procedure Groups—Concise summaries of national statistics from NIS:

Research Notes—A series of publications based on HCUP-3 data, including descriptive statistics on numbers of discharges, length of stay, charges, and mortality rates by diagnosis and procedure:

For further information

For further information on NIS Release 3 and other products, please contact AHCPR:

Healthcare Cost and Utilization Project (HCUP)
Agency for Health Care Policy and Research
Phone: 866-290-HCUP (4287), toll-free
E-mail: hcup@ahrq.gov

AHCPR Publication No. 97-R034
Current as of January 1999

Internet Citation:

Nationwide Inpatient Sample (NIS) Release 3: Fact Sheet. AHCPR Publication No. 97-R034. Agency for Health Care Policy and Research, Rockville, MD. http://www.ahrq.gov/data/hcup/nis3.htm

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