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SID Overview

Overview of the State Inpatient Databases (SID)

The State Inpatient Databases (SID) are part of the family of databases and software tools developed for the Healthcare Cost and Utilization Project (HCUP). The SID includes inpatient discharge records from community hospitals in that State. The SID files encompass all patients, regardless of payer, providing a unique view of inpatient care in a defined market or State over time.

Developed through 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 SID Database Documentation and the Introduction to the SID (PDF file, 456 KB; HTML).


The SID capture hospital inpatient stays in a given State. A number of States make their SID files available for purchase through the HCUP Central Distributor. See Availability of HCUP Data for a list of State database participation and availability by year.

Forty-nine States now participate in the SID:

  • 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 U.S. community hospital discharges. 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, including individuals covered by Medicare, Medicaid, or private insurance, as well as those who are uninsured.
Free HCUP Tools & Software are also available to identify preventable hospitalizations, estimate costs, assess quality of care and patient safety, categorize diagnoses and procedures, and identify comorbidities.

Additional information on the SID may be found in the Introduction to the SID (PDF file, 456 KB; HTML).
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The SID contain clinical and resource-use information that is 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 contain more than 100 clinical and nonclinical variables included in a hospital discharge abstract, such as:

  • Principal and secondary diagnoses and procedures
  • Admission and discharge status
  • Patient demographics characteristics (e.g., sex, age, and, for some States, race)
  • Expected payment source
  • Total charges
  • Length of stay
Elements included in the SID are not always available for all States, including the hospital county identifiers or HCUP's Revisit Variables. Please see the Availability of Data Elements by Year.
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The SID are calendar year files based on discharge date for all data years except 2015. Because of the transition to ICD-10-CM/PCS on October 1, 2015, the 2015 SID are split into two parts. Nine months of the 2015 data with ICD-9-CM codes (discharges from Jan 1, 2015 - September 30, 2015) are in one set of files labeled Q1Q3. Three months of 2015 data with ICD-10-CM/PCS codes (discharges from October 1, 2015 - December 31, 2015) are in a separate set of files labeled Q4. More information about the changes to the HCUP databases for ICD-10-CM/PCS and use of data across the two coding system may be found on the HCUP-US website under ICD-10-CM/PCS Resources.

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Researchers and policymakers use the SID to investigate questions unique to one State, to compare data from two or more States, to conduct market area research or small variation analyses, and to identify State-specific trends in inpatient care. Specific research topics include:

  • Utilization of health services by special populations
  • Use and cost of hospital services
  • Medical practice variation
  • Medical treatment effectiveness
  • Quality of care
  • Impact of health policy changes
  • Access to care
  • Diffusion of medical technology
The SID are used in a variety of publications:

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SID releases beginning in data year 1990 are available for purchase through the HCUP Central Distributor. Costs vary by State and data year.

All HCUP data users, including data purchasers and collaborators, must complete the online HCUP Data Use Agreement Training Tool, and must read and sign the Data Use Agreement for State Databases (PDF file, 251 KB; HTML).

The SID are available for purchase online through the HCUP Central Distributor.

Questions regarding purchasing databases can be directed to the HCUP Central Distributor:

Telephone: (866) 290-4287 (toll free)

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The SID data set comes in ASCII format and can be run on desktop computers with a DVD drive. To load and analyze the SID, you will need the following:

  • A DVD drive
  • A hard drive with one to four gigabytes of space available, depending on the SID being used
  • SAS®, SPSS®, or similar analysis software
The data set comes with full documentation. SID documentation and tools, including programs for loading the ASCII file into SAS or SPSS, are also available on the SID Database Documentation page.

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Internet Citation: HCUP Databases. Healthcare Cost and Utilization Project (HCUP). September 2021. Agency for Healthcare Research and Quality, Rockville, MD.
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Last modified 9/15/21