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Overview of the State Inpatient Databases (SID)
The SID are a set of longitudinal State-specific hospital inpatient databases included in the HCUP family. These databases are created by AHRQ through a Federal-State-Industry partnership.
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State Inpatient Databases

The State Inpatient Databases (SID) are one in a family of databases and software tools developed as part of the Healthcare Cost and Utilization Project (HCUP). A Federal-State-Industry partnership sponsored by the Agency for Healthcare Research and Quality, HCUP data inform decision making at the national, State, and community levels. This page provides an overview of the SID. For more details, see Introduction to the SID (PDF file, 181 KB; HTML).

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The State Inpatient Databases (SID) are a powerful set of hospital databases from data organizations in participating States.
  • The SID contain the universe of the inpatient discharge abstracts in participating States, translated into a uniform format to facilitate multi-State comparisons and analyses.
  • Together, the SID encompass about 97 percent of all annual discharges in the U.S. Some States include discharges from specialty facilities, such as acute psychiatric hospitals.
  • The SID contain a core set of clinical and nonclinical information on all patients, regardless of payer, including persons covered by Medicare, Medicaid, private insurance, and the uninsured.
  • In addition to the core set of uniform data elements common to all SID, some include other elements, such as the patient's race.
The SID contain 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).

The SID exclude data elements that could directly or indirectly identify individuals. Purchase of the files is open to all users who sign a Data Use Agreement (PDF file, 54 KB; HTML). Users must agree to use the database for research and statistical purposes only and to make no attempts to identify individuals.

Identities of institutions are available only in States where data sources already make that information public or agree to its release. For these institutions and for research purposes only, linkage is possible to data from the American Hospital Association (AHA) Annual Survey Database (Health Forum, LLC © 2012).

Select for Introduction to the SID (PDF file, 181 KB; HTML).

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The SID contain more than 100 clinical and nonclinical variables included in a hospital discharge abstract, such as:

  • Principal and secondary diagnoses
  • Principal and secondary procedures
  • Admission and discharge status
  • Patient demographics (e.g., gender, age, and, for some States, race)
  • Expected payment source (e.g., Medicare, Medicaid, private insurance, self-pay; for some States, additional discrete payer categories, such as managed care)
  • Total charges
  • Length of stay
  • For some States, hospital and county identifiers that permit linkage to the American Hospital Association Annual Survey File and the Area Resource File.
A list of SID variables available by State is provided under SID Database Documentation. This section also includes a detailed description of each SID variable. The SID excludes data elements that could directly or indirectly identify individuals.

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Forty Six States now participate in the SID (Select to access contact information for the participating data organization in these States):

Alaska, Arizona, Arkansas, California, Colorado, Connecticut, Florida, Georgia, Hawaii, Illinois, Indiana, Iowa, Kansas, Kentucky, Louisiana, Maine, Maryland, Massachusetts, Michigan, Minnesota, Mississippi, Missouri, Montana, Nebraska, Nevada, New Hampshire, New Jersey, New Mexico, New York, North Carolina, Ohio, Oklahoma, Oregon, Pennsylvania, Rhode Island, South Carolina, South Dakota, Tennessee, Texas, Utah, Virginia, Vermont, Washington, West Virginia, Wisconsin, and Wyoming.

A number of States make SID files available for purchase through the HCUP Central Distributor.

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The SID are well suited for research that requires complete enumeration of hospitals and discharges within market areas or States. Researchers and policymakers use SID to investigate questions unique to one State; to compare data from two or more States; to conduct market area research or small area variation analyses; and to identify State-specific trends in inpatient care utilization, access, charges, and outcomes.

Recent studies using the SID include:
  • Basu J, Friedman B. A Re-examination of Distance as a Proxy for Severity of Illness and the Implications for Differences in Utilization by Race/Ethnicity. Health Economics 2007;16(7):687-701.
  • Coben JH, Steiner CA, Miller TR. Characteristics of Motorcycle-Related Hospitalizations: Comparing States with Different Helmet Laws. Accident Analysis and Prevention 2007;39(1):190-196.
  • Li P, Schneider JE, Ward MM. Effect of Critical Access Hospital Conversion on Patient Safety. Health Services Research 2007;42(6 Pt 1):2089-2108.
  • Misra A. Impact of the HealthChoice Program on Cesarean Section and Vaginal Birth after C-Section Deliveries: A Retrospective Analysis. Maternal and Child Health Journal 2007;12(2):266-74.
  • Smith RB, Cheung R, Owens P, Wilson RM, Simpson L. Medicaid Markets and Pediatric Patient Safety in Hospitals. Health Services Research 2007;42(5):1981-1998.
  • Tate JE, Simonsen L, Viboud C, Steiner C, Patel MM, Curns AT, Parashar UD. Trends in Intussusception Hospitalizations among US Infants, 1993-2004: Implications for Monitoring the Safety of the New Rotavirus Vaccination Program. Pediatrics 2008;121(5):e1125-32.
More publications from the HCUP Database lists recent research using HCUP data.

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The SID data set can be run on desktop computers with a CD-ROM reader, and comes in ASCII format. The data on the CD set require a statistical software package such as SAS or SPSS to use for analytic purposes. The data set comes with full documentation. SAS and SPSS users are provided programs for converting ASCII files.

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SID files beginning in 1990 are available through the AHRQ-sponsored HCUP Central Distributor. The HCUP Central Distributor can provide more detailed, descriptive information on the SID and assist purchasers in completing the application.

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For answers to commonly asked questions regarding HCUP databases and tools, please review the HCUP Index Page. If you cannot find an answer to your question, please contact HCUP User Support Staff.

To reach HCUP User Support, please contact us by e-mail or phone: We review messages daily and will respond to all inquiries within 3 business days.

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Internet Citation: HCUP Databases. Healthcare Cost and Utilization Project (HCUP). January 2013. Agency for Healthcare Research and Quality, Rockville, MD.
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Last modified 1/15/13