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HCUP Facts and Figures 2008
















Adjusted for general inflation
Costs can be adjusted for economy-wide inflation by removing increases that reflect the effect of changing average prices for the same goods and services. In this report, the U.S. Bureau of Economic Analysis Gross Domestic Product Price Index is used to remove economy-wide inflation. Additional inflation that is specific to the hospital sector is not removed in this calculation.

Aggregate costs
Aggregate costs are the sum of all costs for all hospital stays.

Hospital charges reflect the amount the hospital billed for the entire hospital stay and do not include professional (physician) fees. The charge is generally more than the amount paid to the hospital by payers for the hospitalization and is also generally far more than what it costs hospitals to provide care.

Community hospitals
HCUP is based on data from community hospitals, defined as short-term, non-Federal, general and other hospitals, excluding hospital units of other institutions (e.g., prisons). Community hospitals (and HCUP data) include OB-GYN, ENT, orthopedic, cancer, pediatric, public, and academic medical hospitals. They exclude hospitals whose main focus is long-term care, psychiatric, and alcoholism and chemical dependency treatment, although discharges from these types of units that are part of community hospitals are included.

Costs are derived from total hospital charges using cost-to-charge ratios based on hospital accounting reports from the Centers for Medicare and Medicaid Services (CMS). Costs will tend to reflect the actual costs to produce hospital services, while charges represent what the hospital billed for the care. For each hospital, a hospital-wide cost-to-charge ratio is used to transform charges into costs.

  • Principal diagnoses: The conditions established after study to be chiefly responsible for the patient’s admission to the hospital.
  • All-listed diagnoses: The principal diagnosis plus secondary conditions.
  • Secondary diagnoses: The concomitant conditions that coexist at the time of admission or that develop during the stay.
Discharge refers to the hospital stay. The unit of analysis for HCUP data is the hospital discharge, not a person or patient. This means that a person who is admitted to the hospital multiple times in one year will be counted each time as a separate discharge from the hospital.

Discharges per population
Discharges per population is the hospital discharge rate of a particular procedure, diagnosis, or event per number of individuals. This measure indicates the prevalence of hospitalizations, procedures or diagnoses within the population.

Discharge status
Discharge status indicates the disposition of the patient at the time of discharge from the hospital, and includes the following six categories: routine (to home), transfer to another short-term hospital, other transfers (including skilled nursing facility, intermediate care, rehabilitation care, swing bed, and another type of facility such as a nursing home), home healthcare, against medical advice (AMA), or died in the hospital.

Discharge status – Emergency department (ED)
Discharge status indicates the disposition of the patient at the time of discharge from the ED, and includes the following five categories: routine (to home), also known as a treat-and-release visit; transfer to another short-term hospital; admitted as an inpatient to this hospital; other transfers (including skilled nursing facility, intermediate facility, and another type of facility such as a nursing home); and other. Other includes the following: discharged to home healthcare; discharged against medical advice (AMA); died in the ED; not admitted to this hospital, destination unknown; and not admitted to this hospital, discharged alive, destination unknown.

In-hospital deaths
In-hospital deaths refer to hospitalizations in which the patient died during his or her hospital stay.

Infant discharges
Infant discharges are hospital stays during which a child is born.

Length of stay
Length of stay is the number of nights the patient remained in the hospital for his or her stay. A patient admitted and discharged on the same day has a length of stay equal to 0.

Maternal discharges
Maternal discharges are hospital stays for females who are pregnant or gave birth.

Median income
Median income is the median household income of the patient’s ZIP code of residence. Median income is a proxy measure of a patient’s socioeconomic status.
  • Poorest communities are identified as having a median household income of less than $39,000.
  • All other communities are identified as having a median household income greater than or equal to $39,000.
Metropolitan location
Metropolitan location indicates that the hospital is in a metropolitan area ("urban") rather than a non-metropolitan area ("rural"), as defined by the American Hospital Association (AHA) Annual Survey, using the 1993 U.S. Office of Management and Budget definition.

Ownership/control was obtained from the American Hospital Association (AHA) Annual Survey of Hospitals and includes categories for government non-Federal (public), private not-for-profit (voluntary), and private investor-owned (proprietary). These types of hospitals tend to have different missions and different responses to government regulations and policies.

Patient age
Patient age in years, calculated based on the patient's date of birth and admission date to the hospital.

Payer is the expected payer for the hospital stay. To make coding uniform across all HCUP data sources, payer combines detailed categories into more general groups:
  • Medicare includes fee-for-service and managed care Medicare patients.
  • Medicaid includes fee-for-service and managed care Medicaid patients. Patients covered by the State Children’s Health Insurance Program (SCHIP) may be included here. Because most state data do not identify SCHIP patients specifically, it is not possible to present this information separately.
  • Private insurance includes Blue Cross, commercial carriers, and private HMOs and PPOs.
  • Other
  • includes Workers’ Compensation, TRICARE/CHAMPUS, CHAMPVA, Title V, and other government programs.
  • Uninsured
  • includes an insurance status of "self-pay" and "no charge."
When more than one payer is listed for a hospital discharge, the first-listed payer is used.


  • Principal procedure is the procedure that was performed for definitive treatment rather than one performed for diagnostic or exploratory purposes (i.e., the procedure that was necessary to take care of a complication). If two procedures appear to meet this definition, the procedure most related to the principal diagnosis is selected as the principal procedure.
  • All-listed procedures include all procedures performed during the hospital stay.
The unit of analysis for HCUP data is the hospital stay (i.e., the hospital discharge), not a person or patient. This means that a person who is admitted to the hospital multiple times in one year will be counted each time as a separate "discharge" from the hospital.

Treat-and-release ED visits
Treat-and-release ED visits are those ED visits in which patients are treated and released from the ED (i.e., they are not admitted to the specific hospital in which the ED is located). While the majority of treat-and-release patients are discharged home, some are transferred to another acute care facility, leave against medical advice, go to another type of long-term or intermediate care facility (nursing home or psychiatric treatment facility), are referred to home healthcare, die, or are discharged alive but the destination is unknown.


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Internet Citation: Facts and Figures 2008 - Definitions. Healthcare Cost and Utilization Project (HCUP). October 2010. Agency for Healthcare Research and Quality, Rockville, MD.
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Last modified 10/7/10