Healthcare Cost and Utilization Project

The Healthcare Cost and Utilization Project (HCUP, pronounced "H-Cup") is a family of health care databases and related software tools and products from the United States that is developed through a Federal-State-Industry partnership and sponsored by the Agency for Healthcare Research and Quality (AHRQ).^[1]

HCUP Logo

General Information

HCUP provides access to health care databases for research and policy analysis, as well as tools and products to enhance the capabilities of the data.^[2]

HCUP databases combine the data collection efforts of State data organizations, hospital associations, private data organizations, and the Federal government to create a national information resource of patient-level health care data. State organizations that provide data to HCUP are called HCUP Partners.

HCUP includes the largest collection of multi-year hospital care (inpatient, outpatient, and emergency department) data in the United States, with all-payer, encounter-level information beginning in 1988. These databases enable research on a broad range of health research and policy issues at the national, state, and local market levels, including cost and quality of health services, medical practice patterns, access to health care, and outcomes of treatments.

Additionally, AHRQ has developed a comprehensive set of software tools to be used when evaluating hospital data. AHRQ's free software tools can be used not only with the HCUP databases, but also with other administrative databases. HCUP's Supplemental Files are only for use with HCUP databases.

HCUP User Support Website (HCUP-US)

The HCUP-US Website is the main repository of information for HCUP. It is designed to answer HCUP-related questions; provide detailed information on HCUP databases, tools, and products; and offer technical assistance to HCUP users. HCUP’s tools, publications, documentation, news, services, and HCUPnet (the free online data query system) may all be accessed through HCUP-US. The Website also provides information on how to obtain HCUP databases.

HCUP-US is located at http://www.hcup-us.ahrq.gov'''.

HCUP Overview Course

To help researchers and policymakers discover and use HCUP’s data, tools, and products to their fullest potential, HCUP developed a free, interactive online course that provides an overview of the features, capabilities, and potential uses of HCUP. The course is modular, so users can either move through the entire course or access exactly the resources in which they are most interested. The Overview Course can work both as an introduction to HCUP data and tools and a refresher for established users.

HCUP Online Tutorial Series

The HCUP Online Tutorial Series is a set of free, interactive training courses that provide users with information about HCUP data, software products, and tools and give guidance on technical methods for conducting research with HCUP data. The online courses are modular, so users can move through an entire course or access the sections in which they are most interested. Available tutorials feature topics such as loading HCUP data, HCUP’s sampling design, weighting the databases, calculating standard errors, producing national estimates, and conducting multi-year analysis.

HCUP Databases

Overview of HCUP Databases

HCUP databases bring together the data collection efforts of State data organizations, hospital associations, private data organizations, and the Federal government to create an information resource of patient-level health care data.

HCUP’s databases date back to 1988 data files. The databases contain encounter-level information for all payers compiled in a uniform format with privacy protections in place. Researchers and policymakers can use its records to identify, track, and analyze national trends in health care use, access, charges, quality, and outcomes. The databases are suited for a broad range of analyses—including rare conditions and special patient populations.

HCUP databases are released approximately 6–18 months after the end of a given calendar year, with State databases available earlier than the national dataset. For example, 2012 State data was available beginning in 2013, and nationwide data was available beginning in July 2014.

Currently there are six types of HCUP databases: three with national- and regional-level data and three with State- and local-level data.

National Databases—for national and regional analyses

National Inpatient Sample (NIS) (formerly the Nationwide Inpatient Sample): Annual inpatient data from a stratified systematic sample of discharges from all hospitals in HCUP, equal to approximately 20 percent of all discharges in U.S. community hospitals, excluding rehabilitation and long-term acute-care hospitals. Data are available from 1988 forward, and a new database is released annually, approximately 18 months after the end of a calendar year. The NIS Overview and the NIS Database Documentation pages of the HCUP-US Web site contain additional information. Data are available from 1988 forward, and a new database is released annually, approximately 18 months after the end of a calendar year.

Kids' Inpatient Database (KID): A nationwide sample of pediatric inpatient discharges designed specifically for users to study a broad range of conditions and procedures related to child health issues. The KID is released every three years, from 1997 forward.

Nationwide Emergency Department Sample (NEDS): A database of over 25 million records that yields national estimates of emergency department (ED) visits. The NEDS captures encounters where the patient is admitted for inpatient treatment, as well as those in which the patient is treated and released. The NEDS is released annually and is available from 2006 forward.

State Databases—for state and local analyses

The State Inpatient Databases (SID): Databases from the universe of inpatient discharge abstracts from participating States, released annually. Data are available from 1995 forward. The SID are released on a rolling basis, as early as six months following the end of a calendar year.

The State Ambulatory Surgery and Services Databases (SASD): Ambulatory surgery encounter abstracts from hospital-affiliated and sometimes freestanding ambulatory surgery sites in participating States. Data are available from 1997 forward. The SASD are released on a rolling basis, as early as six months following the end of a calendar year.

The State Emergency Department Databases (SEDD): Hospital-affiliated emergency department data for visits in participating States that do not result in hospitalizations. Data are available from 1999 forward. The SID are released on a rolling basis, as early as six months following the end of a calendar year.

The price of the data varies by the database and year. Recent years of the NIS and KID are $350 per data-year, with a special rate for students of $50. The NEDS is $500 per data-year, and $75 for students. The cost of the State databases is set by the individual State Partner supplying the data to HCUP. Pricing varies by State and database, and certain Partners may have different prices for the type of organization requesting the data (non-profit, government, academic, etcetera). Purchasing and pricing information can be found on the HCUP User Support Website at http://www.hcup-us.ahrq.gov/tech_assist/centdist.jsp.

Redesign of the 2012 NIS

Starting with data year 2012, a new sampling method was implemented to improve national estimates. Prior to 2012, the NIS included all discharges from a 20 percent sample of U.S community hospitals, excluding rehabilitation hospitals. Starting with data year 2012, the NIS consists of a sample of discharges from all hospitals participating in HCUP, equal to approximately 20 percent of all discharges in U.S. community hospitals, excluding rehabilitation and long-term acute-care hospitals. The revised sample design provides a reduced the margin of error. To highlight the design change, beginning with 2012 data, AHRQ renamed the NIS from the Nationwide Inpatient Sample to the National Inpatient Sample.^[3]

More information about the NIS redesign can be found in the NIS Redesign Final Report.

Obtaining HCUP databases through the Central Distributor

A number of HCUP State Partners make their data available for purchase through the HCUP Central Distributor. Applications for the databases are available on its Website. Please note, prospective purchasers and all persons with access to the databases are required to take the Data Use Agreement Training Course and sign the Data Use Agreement before using the data.

HCUP Tools and Software

To enhance the capabilities of the HCUP databases, HCUP provides a number of tools and software programs that can be applied to HCUP and other similar administrative databases. Many are available for download from the HCUP-US Website. Others may be ordered through the HCUP Central Distributor. All of HCUP’s tools and software products are free-of-charge.

HCUPnet

HCUPnet is a free, online, interactive query system based on HCUP data. HCUPnet provides statistics from the HCUP national databases (the NIS and KID) and from the State databases (the SID and SEDD) for those States that have agreed to participate.

HCUPnet can be used for identifying, tracking, analyzing, and comparing statistics on hospital and emergency care, as well as obtaining measures of quality based on the AHRQ Quality Indicators. HCUPnet can also be used for trend analysis with health care data available from 1993 forward.

Hospitals Like Mine

In addition to national and State statistics, HCUPnet includes a feature called Hospitals Like Mine, which allows users interested in certain types of hospitals to create national statistics based on hospital characteristics. Based on the NIS, American Hospital Association (AHA) survey, and Hospital Compare, the Hospitals Like Mine function allows users to analyze the types of patients that are seen, the services offered, and how these types of hospitals score on various quality measures.

Hospital Readmissions

HCUPnet also includes a feature called Hospital Readmissions which provides users with some statistics on hospital readmissions within 30 days of hospital discharge. Information on calculating readmissions for HCUPnet is available in the HCUP Methods Series report.

Quality Indicators (QIs)

The AHRQ Quality Indicators (QIs) are measures of health care quality that make use of readily-available hospital inpatient administrative data. AHRQ QIs can be used to highlight potential quality concerns, identify areas that need further study and investigation, and track changes over time.

The AHRQ QIs consist of four modules measuring various aspects of quality:

Prevention QIs identify hospital admissions that evidence suggests could have been avoided, at least in part, through high-quality outpatient care.

Inpatient QIs reflect quality of care inside hospitals including inpatient mortality for medical conditions and surgical procedures.

Patient Safety Indicators also reflect quality of care inside hospitals, but focus on potentially avoidable complications and iatrogenic events.

Pediatric QIs both reflect quality of care inside hospitals and identify potentially avoidable hospitalizations among children.

Recently, problems related to these quality indicators have arisen. They may be subject to ascertainment bias-meaning that the more one looks for complications, the more they are found and a hospitals quality score will worsen. Alternatively, a low quality hospital may not be very vigilant, not look very hard for complications and have a good score based on quality indicators.^[4]

Clinical Classifications Software (CCS)

The Clinical Classifications Software (CCS) provides a method for classifying diagnoses or procedures into clinically meaningful categories, which can be used for aggregate statistical reporting of a variety of topics, such as identifying populations for disease- or procedure-specific studies, or developing statistical reports providing information (i.e., charges and length of stay) about relatively specific conditions.

There are four versions of the CCS. Some of the more commonly-used versions include the CCS for ICD-9-CM, the CCS for ICD-10-CM (beta), and the CCS for ICD-10.

Clinical Classifications Software (CCS) for ICD-9-CM is based on the International Classification of Diseases, 9th Revision, Clinical Modification (ICD-9-CM), a uniform and standardized coding system. The CCS for ICD-9-CM provides a method for classifying ICD-9-CM diagnoses or procedures into clinically meaningful categories, which can be used for aggregate statistical reporting of a variety of topics and employed in many types of projects analyzing data on diagnoses and procedures.

The ICD-9-CM's multitude of codes—currently over 13,600 diagnosis codes and 3,700 procedure codes—are collapsed into a smaller number of clinically meaningful categories. The current CCS for ICD-9-CM version has 289 categories for diagnoses and 231 for procedures. For certain research interests, this smaller number can be more useful for presenting descriptive statistics than individual ICD-9-CM codes.

Since Fiscal Year 2008, CCS for ICD-9-CM includes categories from the Mental Health and Substance Abuse Clinical Classifications Software (CCS-MHSA). These categories replace the original CCS categories for mental health and substance abuse. Specifically, the CCS single-level software includes the CCS-MHSA general categories, and the CCS multi-level software includes the CCS-MHSA specific categories.

The CCS for ICD-9-CM is updated annually.

Clinical Classifications Software (CCS) for ICD-10-CM clusters ICD-10-CM diagnosis and ICD-10-PCS procedure codes into a manageable number of clinically meaningful categories. This tool is currently in beta version and available for public evaluation.

Clinical Classifications Software (CCS) for ICD-10 is based on the International Classification of Diseases, 10th Revision (ICD-10), a uniform and standardized coding system which has been used in the U.S. for mortality reporting since 1999. focused on mortality reporting. The CCS for ICD-10 tool is valid through September 2009.

The CCS version and their user guides are available for download from the HCUP-US Website.

Chronic Condition Indicator

The Chronic Condition Indicator provides researchers a way to categorize all of the ICD-9-CM’s approximately 13,600 current diagnosis codes into two categories: chronic or not chronic. A chronic condition is defined as a condition that lasts 12 months or longer and meets one or both of the following tests: (a) it places limitations on self-care, independent living, and social interactions; and (b) it results in the need for ongoing intervention with medical products, services, and special equipment. The identification of chronic conditions is based on all 5-digit ICD-9-CM codes. E Codes, or external cause of injury codes, are not classified, because all injuries are assumed to be acute.

The tool also assigns ICD-9-CM diagnosis codes into one of 18 body system categories, allowing users to create indicators listing which specific body systems are affected by a chronic condition. The body system indicator is based on the chapters of the ICD-9-CM codebook. This indicator may be useful as a means of counting the number of body systems affected by chronic conditions. Alternatively, the Clinical Classification Software (CCS) may be used in conjunction with the Chronic Condition Indicator in order to obtain a count of the number of relatively discrete chronic conditions.

The Chronic Condition Indicator is updated annually and is valid for codes from January 1, 1980 forward. The indicator may be downloaded from the HCUP Central Distributor.

Comorbidity Software

Comorbidity Software assigns variables that identify coexisting conditions on hospital discharge records that may contribute to a patient’s death using ICD-9-CM diagnosis coding.

The Comorbidity Software consists of two computer programs. The first, Creation of Format Library for Comorbidity Groups, generates a format library that maps diagnosis codes into comorbidity indicators. Additional formats are created to exclude conditions that may be complications or that may be related to the principal diagnosis. The second program, Creation of Comorbidity Variables, applies these formats to a data set containing administrative data.

The Comorbidity Software is updated annually and available for download on the HCUP-US Website.

Cost-to-Charge Ratio Files (CCR)

The Cost-to-Charge Ratio (CCR) Files are hospital-level files designed to convert the hospital total charge data to cost estimates when merged with data elements in the NIS, SID, and KID.

The HCUP databases are limited to information on total hospital charges, which reflect the amount billed to the payer per patient encounter. Total charges do not reflect the actual cost of providing care or the payment received by the hospital for services provided. This total charge data can be converted into cost estimates using the CCR Files, which include hospital-wide values of the all-payer inpatient cost-to-charge ratio for nearly every hospital in the participating SID, NIS, and KID. Researchers and policy makers can use the converted cost estimates to examine a variety of topics, including use and cost of hospital services, health care cost inflation, and how the cost experiences of a given hospital or health plan compare with national or state trends.

The Cost-to-Charge Ratio Files are updated annually. The files may be obtained free-of-charge from the HCUP Central Distributor, ensuring that users receive the proper version of the CCR for the year of interest.

Hospital Market Structure (HMS) Files

The Hospital Market Structure (HMS) Files are hospital-level files designed to supplement the data elements in the NIS, KID, and SID databases. The HMS Files contain various measures of hospital market competition. These measures are aggregate and are meant to broadly characterize the intensity of competition that hospitals may be facing under various definitions of market area.

Hospital market definitions were based on hospital locations, and in some cases, patient ZIP Codes. Hospital locations were obtained from the American Hospital Association (AHA) Annual Survey Database, Area Resource File (ARF), HCUP Historical Urban/Rural – County (HURC) file, and ArcView GIS. Patient ZIP Codes were obtained from the SID.

Users can merge the data elements on the Hospital Market Structure Files to the corresponding NIS, KID, or SID hospitals by the hospital identification number (HOSPID). Using the merged data elements, hospital market structure measures can then be included in analyses.

Hospital market structure measures are generally useful for performing empirical analyses that examine the effects of hospital competition on the cost, access, and quality of hospital services. They are most useful to analysts as a secondary control variable (e.g., for assessing whether a statistical relationship exists between two variables when hospital market structure is controlled).

The Hospital Market Structure Files are updated every three years and available free-of-charge from the HCUP Central Distributor. The HCUP Hospital Market Structure Files are currently available for 1997, 2000, and 2003.

HCUP Supplemental Files for Revisit Analyses

The HCUP Supplemental Files for Revisit Analyses allows users to track sequential visits for a patient within a state and across facilities and hospitals settings while adhering to strict privacy guidelines. The available clinical information can determine if these sequential visits are unrelated, an expected follow-up, complications from a previous treatment, or an unexpected revisit or rehospitalization. Users must merge the supplemental files with the corresponding SID, SASD, or SEDD for any analysis. Data are available from 2003 forward.

Procedure Classes

Procedure Classes facilitate research on hospital services using administrative data by identifying whether an ICD-9-CM procedure is (a) diagnostic or therapeutic, and (b) minor or major in terms of invasiveness and/or resource use.

The Procedure Classes provide users an easy way to categorize procedure codes into one of four broad categories: Minor Diagnostic, Minor Therapeutic, Major Diagnostic, and Major Therapeutic.

Minor Diagnostic: Non-operating room procedures that are diagnostic (e.g., 87.03: CT scan of head)

Minor Therapeutic: Non-operating room procedures that are therapeutic (e.g., 02.41: Irrigate ventricular shunt)

Major Diagnostic: All procedures considered valid operating room procedures by the Diagnosis Related Group (DRG) grouper and that are performed for diagnostic reasons (e.g., 01.14: Open brain biopsy)

Major Therapeutic: All procedures considered valid operating room procedures by the Diagnosis Related Group (DRG) grouper and that are performed for therapeutic reasons (e.g., 39.24: Aorta-renal bypass).

Procedure codes for this tool are based on the ICD-9-CM.

The Procedure Classes are updated annually and available for download from the HCUP-US Website.

Utilization Flags

Utilization Flags reveal additional information about use of health care services by combining information from UB-92 revenue codes and ICD-9-CM procedure codes to create flags—or indicators—of utilization for a more complete picture of the services rendered in hospitals, emergency departments, and ambulatory surgery centers.

The Utilization Flags can be employed to study issues such as use of intensive care units, as well as to reliably examine utilization of diagnostic and therapeutic services—beyond the information that can be gleaned from ICD-9-CM procedure codes alone.

The Utilization Flags are updated annually and available for download from the HCUP-US Website.

NIS & KID Trend Files

The NIS-Trends and KID-Trends files are available to help researchers conduct longitudinal analyses. They are discharge-level files that provide researchers with the trend weights, and data elements in the case of the NIS-Trends, that are consistently defined across data year.

MONAHRQ

MONAHRQ is a free, downloadable software product that supports web-based public reporting of healthcare quality measures. It is a product of the Agency for Healthcare Research and Quality (AHRQ), part of the United States Department of Health and Human Services (DHHS).

MONAHRQ was first publicly released in June 2010.

HCUP News and Reports

HCUP produces material to report new findings based on HCUP data and to announce HCUP news.

HCUP Infographic: 30-Day Readmission Rates to U.S. Hospitals, 2010

HCUP Infographic: The Top Five Most Expensive Conditions Treated in U.S. Hospitals, 2011

HCUP Infographic: Adverse Drug Events Occurring in U.S. Hospitals, 2011

HCUP eNews

HCUP’s eNews provides a summary of quarterly activities of the HCUP project. Issues are released in March, June, September, and December.

HCUP Mailing List

The HCUP Mailing List provides e-mail updates on news, product releases, events, and the quarterly eNews.

HCUP Statistical Briefs

HCUP's Statistical Brief series presents descriptive statistics on a variety healthcare and health services topics containing data from the HCUP databases.

HCUP Infographics

The HCUP infographics provide a visual representation of data found in the HCUP Statistical Brief series. Topics have included 30-day readmissions, the most expensive conditions seen in U.S. hospitals, and adverse drug events occurring in U.S. hospitals.

References

↑ What is HCUP?
↑ Fact Sheet: Databases and Related Tools from the Healthcare Cost and Utilization Project (HCUP)
↑ , Available on HCUP-US.ahrq.gov
↑ Bilimoria, Karl (October 9, 2013). "Evaluation of Surveillance Bias and the Validity of the Venous Thromboembolism Quality Measure". JAMA. doi:10.1001/jama.2013.280048. PMID 24100354. Retrieved Feb 12, 2015.