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HCUPnet Glossary

Admission from another hospital - The patient was admitted to this hospital from another short term, acute-care hospital. This usually signifies that the patient required the transfer in order to obtain more specialized services that the originating hospital could not provide. Not available for 2007 and after.

Admission from long term care facility - The patient was admitted from a long term facility such as a nursing home. Not available for 2007 and after.

Admission Source - The definition changed in 2007. Not all data sources had adopted the change at that time; therefore, information on source of admission is not available for 2007 and after.

Admitted from the ED - Indicates whether patient was admitted to the hospital through the ED.

Age group - In years, calculated on the basis of the admission date to the ED or the hospital.

Aggregate ED and hospital charges - Also called the "national bill" -- the sum of all charges for all hospital stays in the U.S. Includes both ED and hospital charges for stays admitted through the ED.

Aggregate ED and hospital costs - The sum of all ED and hospital costs for all hospital stays admitted through the ED. See Costs and Aggregate ED and hospital charges for details.

Aggregate year range - In the community-level statistics path, three years of data may be combined to yield larger cell sizes resulting in fewer cases where data need to be suppressed.

All stays - All patients in general, not by specific diagnoses or procedures.

All-listed diagnoses - Include the first-listed or principal diagnosis plus additional conditions that coexist at the time of the ED visit, or that develop during the stay following the ED visit, and which have an effect on the treatment or length of stay in the ED or hospital. If you want detailed information on ED visits, such as total ED charges for a particular diagnosis or discharge status for ED visits for a particular diagnosis - choose "First-listed" (discharged from the ED visits) or "Principal" (visits that result in admission to the same hospital) When you choose"All-listed," you only get the number of ED visits with that diagnosis (no details on charges or discharge status). The unit of analysis remains the visit: if a particular diagnosis occurs multiple times during the same visit, it is still counted only once.

All-listed procedures - Include all surgeries and diagnostic tests performed during the ED visit or following hospital stay (for those visits that resulted in admission). When you choose "All-listed," you only get the number of visits with that procedure (no details on charges, or discharge status). The unit of analysis remains the visit: if a particular procedure occurs multiple times during the same visit, it is still counted only once.

Ambulatory surgeries - Limited to invasive surgery commonly performed for therapeutic purposes (i.e., to treat disease or injury). Excluded were noninvasive surgeries and procedures typically used for diagnostic or exploratory purposes (e.g., colonoscopy). The HCUP Surgery Flag software was used to identify invasive, therapeutic surgeries based on a narrow, targeted, and restrictive definition that includes surgical procedures involving incision, excision, manipulation, or suturing of tissue that penetrates or breaks the skin; typically require use of an operating room; and also require regional anesthesia, general anesthesia, or sedation to control pain. If a procedure appears more than once on the record, it is de-duplicated, i.e., counted only once.

Ambulatory Surgery Principal Procedures - Some ambulatory surgery and services databases use ICD-9-CM codes for procedures, some use CPT codes, and some use both. CPT refers to the Common Procedural Terminology, a system used to reimburse for professional services. The Clinical Classification Software (CCS) was developed for use with ICD-9-CM codes, but a version is also maintained for CPT codes -- CCS for Services and Procedures When a state database includes both ICD-9-CM and CPT procedure codes, the coding system that is predominant (i.e., available for the larger number of records) is used to identify the first-listed procedure. For example, if CPT codes are predominant in the data, the first-listed CPT code is used as the first-listed procedure. All remaining codes -- both ICD-9-CM and CPT -- are considered secondary procedures and are included in all-listed procedures.

Associated first-listed or principal diagnoses - First-listed or principal diagnoses that appear with the procedure that you chose, for example, "For what conditions do patients receive total hip replacement?" For patients discharged from the ED, this is the first-listed diagnosis; for visits that result in admission to the same hospital, this is the first-listed diagnosis that occurred during the ED visit or (more likely) the principal diagnosis during the hospital stay.

Associated First-listed or principal procedures - First-listed or principal procedures that appear with the diagnosis you chose, for example, "What principal procedures are received by patients with acute myocardial infarction?" For patients discharged from the ED, this is the first-listed procedure; for visits that result in admission to the same hospital, this is the first-listed procedure that occurred during the ED visit or (more likely) the principal procedure during the hospital stay.

Bedsize - The size of the hospital in terms of the number of short-term, acute care beds.

Children's hospitals - Defined based on information from the AHA Annual Survey of Hospitals as well as the Children's Hospital Association, formerly known as the National Association of Children's Hospitals and Related Institutions. The designation of "Free-standing children's hospital" is based on the AHA Annual Survey. This is the narrowest definition of a children's hospital and excludes "children's hospitals within hospitals." The designation of "Children's hospitals, including children's units within other hospitals" is based on data from the Children's Hospital Association and comprises a broad definition of children's hospitals (data element = NACHTYPE in the 1997-2009 Kids' Inpatient Database (KID); no longer available in the 2012 KID). Both definitions are provided here for continuity in statistics over the years presented in HCUPnet.

Clinical Classifications Software (CCS) - Categorizes diagnoses and procedures into a manageable number of clinically meaningful categories. The CCS for ICD-9-CM categorizes the 12,000 diagnosis codes and 3,500 procedure codes from the International Classification of Diseases, 9th Revision, Clinical Modification (ICD-9-CM) into about 260 diagnosis categories and 230 procedure categories. This "clinical grouper" makes it easier to quickly understand patterns of diagnoses and procedures. Each hospital stay, ED visit, or ambulatory surgery can have multiple diagnoses and multiple procedures. CCS was developed at the Agency for Healthcare Research and Quality (AHRQ)."

Clinical Classifications Software for Services and Procedures - CCS for Services and Procedures categorizes Current Procedural Terminology (CPT®) codes and Healthcare Common Procedure Coding System (HCPCS) codes into clinically meaningful procedure categories.

Clinical Classifications Software Refined (CCSR) for Diagnosis (ICD-10-CM) - Categorizes ICD-10-CM diagnoses into a manageable number of clinically meaningful categories. The CCSR for ICD-10-CM diagnoses aggregates more than 70,000 ICD-10-CM diagnosis codes into over 530 clinical categories across 21 body systems. All ICD-10-CM codes are mapped to a clinical category. Some diagnosis codes are cross classified into more than one category because individual ICD-10-CM codes can describe multiple conditions or a condition and a common symptom/manifestation. This "clinical grouper" makes it easier to quickly understand patterns of diagnoses and procedures. Each hospital stay, ED visit, or ambulatory surgery can have multiple diagnoses and multiple procedures. CCS was developed at the Agency for Healthcare Research and Quality (AHRQ).

Clinical Classifications Software Refined for Procedures (ICD-10-PCS) - The CCSR for ICD-10-PCS procedures aggregates more than 80,000 ICD-10-PCS procedure codes into over 320 clinical categories across 31 clinical domains. All ICD-10-PCS codes are classified into only one CCSR category. The CCSR for ICD-10-PCS procedures is intended to be used analytically to examine patterns of healthcare in terms of cost, utilization, and outcomes, in addition to perform rank utilization by procedures.

Costs - Costs Tend to reflect the actual costs of production, whereas charges represent what the hospital billed for the stay. Total charges were converted to costs using cost-to-charge ratios based on hospital accounting reports from the Centers for Medicare and Medicaid Services (CMS). In general, costs are less than charges. For each hospital, a hospital-wide cost-to-charge ratio is used because detailed charges are not available across all HCUP States.

Diagnosis - Specific condition or disease affecting hospitalized patients.

Diagnosis Related Groups (DRGs) - A classification system that categorizes patients into clinically coherent and homogeneous groups with respect to resource use according to diagnosis, procedures, age, and other criteria relevant to resource use. Each hospital stay has one DRG and one MDC assigned to it. For data years prior to 2008 HCUPnet uses CMS DRGs. Starting in 2008 HCUPnet uses Medicare Severity Diagnosis Related Groups (MS-DRGs). DRGs prior to 2008 cannot be compared with DRGs from 2008 and later. CMS DRGs and MS-DRGs are separate options in all classification system selection boxes. A query may only contain codes from one of these two systems.

Died - Indicates ED mortality (patient died in the ED) or in-hospital mortality (patient died in the hospital following admission from the ED).

Discharge - The unit of analysis for HCUP data is the hospital encounter, not a person or patient (i.e.,HCUP focuses on the ED visit or the ED visit in addition to the hospital stay). This means that a person who is seen in the ED multiple times in one year will be counted each time as a separate "ED visit."

Discharge status - The disposition of the patient at discharge from the hospital, e.g., routine (home), to another short-term hospital, to a nursing home, to home health care, or against medical advice

Discharged from the ED - Those ED visits in which patients are released from the ED or transferred (i.e., they are not admitted to the specific hospital in which the ED is located). While the majority of patients discharged from the ED 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 health care, die, or are discharged alive but the destination is unknown.

Discharged to another institution - The percentage of stays that resulted in transfer to a long-term facility such as a nursing home.

Discharged to another short term hospital - The percentage of stays that resulted in transfer to another short-term, acute-care hospital.

Dually eligible - Includes patients who are covered by both Medicare and Medicaid.

ED and hospital charges - The amount the hospital charged for the entire hospital stay, excluding professional (MD) fees. If you asked for information about procedures, charges will reflect the total hospital charge, not the charge for that procedure. Charges do not necessarily reflect how much the hospital was reimbursed. You can choose mean or median charges. Mean is the average. Median is the midpoint: half of the cases are below this value and half are above this value. The median is provided because the mean can be strongly influenced by extreme values.

Emergency admission - Indicates whether or not the patient was admitted to the hospital through the emergency department. Not available for 2007 and after.

External Cause of Injury (CCS E Codes) - Groups causes of injuries or poisonings into 21 categories

External Cause of Injury (E Codes) - Describes the cause of injuries or poisonings, the intent and place were they occurred

FIPS - Federal information Process System (FIPS) Codes are numbers that uniquely identify geographic areas. State FIPS codes have 2 digits, and county FIPS codes have 5 digits, of which the first 2 are the FIPS code of the state for each county.

First-listed or principal diagnosis - ICD-9-CM: The diagnosis that appears first on the record. For ED visits that result in hospital admission, this is the principal diagnosis. The principal diagnosis is the condition that is the main reason for the hospital admission as recorded on the Uniform Bill (UB-04). For patients discharged from the ED, it may not be the principal diagnosis but may simply be the diagnosis that appears first on the record.

ICD-10-CM: For inpatient stays the principal diagnosis is that condition established after study to be chiefly responsible for the patient’s admission to the hospital. For ED visits, the first-listed diagnosis should represent the condition, symptom, or problem identified in the medical record to be chiefly responsible for the emergency department (ED) services provided. Additionally, ICD-10-CM Coding Guidelines acknowledge cases where the first-listed diagnosis may be a symptom when a diagnosis has not been established by the provider. Given this nuance, HCUP recommends researchers also consider the clinical perspective when determining the reasons for ED visits. For ED visits that result in an inpatient admission to the same hospital, the first-listed diagnosis is the principal diagnosis, the condition established after study to be chiefly responsible for the patient’s admission to the hospital.

First-listed or principal procedure - ICD-9-PCS: The procedure that was performed for definitive treatment rather than one performed for diagnostic or exploratory purposes, or the procedure that was necessary to take care of a complication. If two procedures appear to meet this definition, the one most related to the principal diagnosis should be selected as the principal procedure. (Definition according to Coding Clinic, fourth quarter 1990, page 5.) For ED visits that result in hospital admission, this is the principal procedure (which may have occurred during the ED visit but more likely during the hospital stay). For ED visits that result in discharge (no hospital admission), it may not be the principal procedure performed during the ED visit but may simply be the procedure that appears first on the record.

ICD-10-PCS: The principal procedure is supposed to be the procedure performed for definitive treatment most related to principal diagnosis. However, ICD-10-PCS coding rules are nuanced as to the type of procedure performed for a given diagnosis. Users are strongly recommended to review ICD-10-PCS Coding Guidelines as they determine their procedure query: https://www.cms.gov/files/document/2021-official-icd-10-pcs-coding-guidelines-updated-december-1-2020.pdf

Free-standing Children's hospitals - Defined based on information from the AHA Annual Survey of Hospitals as well as the Children's Hospital Association, formerly known as the National Association of Children's Hospitals and Related Institutions. The designation of "Free-standing children's hospital" is based on the AHA Annual Survey. This is the narrowest definition of a children's hospital and excludes "children's hospitals within hospitals." The designation of "Children's hospitals, including children's units within other hospitals" is based on data from the Children's Hospital Association and comprises a broad definition of children's hospitals (data element = NACHTYPE in the 1997-2009 Kids' Inpatient Database (KID); no longer available in the 2012 KID). Both definitions are provided here for continuity in statistics over the years presented in HCUPnet.

General Conditions - Categorizes discharges into five hospitalization types (i.e., general conditions) in the following hierarchical order: maternal/neonatal, mental health/substance abuse, injury, surgical, and medical. Adult discharges are categorized into six hospitalization types in the following hierarchical order: maternal, neonatal, mental health/substance use, injury, surgical, and medical. Each general conditions is defined in the Methodology here.

Highest severity of illness - Discharges with highest severity of illness have major or extreme severity of illness on the APR-DRG severity scale

ICD-10-CM - The "International Classification of Diseases - 10th revision - Clinical Modification." Beginning in October 2015, all diagnoses (or conditions) that patients receive are assigned an ICD-10-CM code. Each ICD-10-CM code can be up to 7 characters long. ICD-10-CM contains more than 70,000 diagnosis codes, and each medical event can have multiple diagnoses recorded.

ICD-10-PCS - The "International Classification of Diseases - 10th revision – Procedure Coding System." Beginning in October 2015, all inpatient procedures that patients receive are assigned an ICD-10-PCS code. Each ICD-10-PCS code can be up to 7 characters long. ICD-10-PCS contains more than 80,000 procedures codes, and each record can have multiple procedures recorded.

ICD-9-CM - The "International Classification of Diseases - 9th revision - Clinical Modification." All diagnoses (or conditions) and all procedures that patients receive are assigned an ICD-9-CM code. Codes for ICD-9 diagnoses can be up to 5 digits long and codes for procedures can be up to 4 digits long. There are about 12,000 diagnosis codes and about 3,500 procedure codes. Each record can have multiple diagnoses and multiple procedures.

In-hospital deaths - Death during the hospital stay (in-hospital mortality).

Length of hospital stay following an ED visit - The number of nights the patient remained in the hospital for this stay. A patient admitted and discharged on the same day has a length of stay = 0. You can choose the mean or median. Mean is the average. Median is the midpoint: half of the cases are below this value and half are above this value. The median is provided because the mean can be strongly influenced by extreme values.

Location - The hospital is in a metropolitan area ("urban") or non-metropolitan area ("rural"), as defined by American Hospital Association (AHA) Annual Survey, using the 1993 U.S. Office of Management and Budget definition.

Location of patient's residence - Rural/urban designation of patient"s county of residence

Major Diagnosis Categories (MDCs) - Broad groups of DRGs (Diagnosis Related Groups) that relate to an organ or a system and not to an etiology. For example, MDC 01 is Diseases and Disorders of the Nervous System, MDC 02 is Diseases and Disorders of the Eye, and MDC 03 is Diseases and Disorders of the Ear, Nose, Mouth and Throat. Each hospital stay has one DRG and one MDC assigned to it.

Maternal discharges - Maternal discharges were identified using the Major Diagnostic Category (MDC) 14 Pregnancy, Childbirth and the Puerperium. MDCs were assigned without using "present on admission" information on the record because not all HCUP data sources provide present on admission indicators. This prevents assignment of the standard MDC for records involving Hospital Acquired Conditions (HAC) and would have resulted in missing data.

Median income - The median household income of the patient's ZIP code of residence. HCUPnet allows you to compare patients that come from very low-income ZIP Codes to patients who come from higher-income ZIP Codes. The definition of very low income is the lowest quartile of income. This is a proxy measure of a patient's socioeconomic status. Median household income is only available for National statistics. Data are only available from 2003 forward.

Most common diagnoses and procedures - Lists the top 100 DRGs, diagnoses, or procedures in U.S. hospitals and then provides you with the most common diagnoses and procedures for each.

National bill - Also called "aggregate charges" -- the sum of all charges for all hospital stays in the U.S.

Neonatal discharges - Neonatal discharges were identified using the Major Diagnostic Category (MDC) 15 Newborns and Other Neonates with Conditions Originating in the Perinatal Period. MDCs were assigned without using "present on admission" information on the record because not all HCUP data sources provide present on admission indicators. This prevents assignment of the standard MDC for records involving Hospital Acquired Conditions (HAC) and would have resulted in missing data.

Operating room procedures - Defined as "valid OR procedures" based on Diagnosis Related Groups coding principles.

Ownership/control - Categorizes hospitals into (1) government nonfederal (public), (2) private not-for-profit (voluntary) and (3) private investor-owned (proprietary). Obtained from the American Hospital Association (AHA) Annual Survey of Hospitals.. These types of hospitals tend to have different missions and responses to government regulations and policies.

Payer - The expected payer, based on the first-listed payer

Pediatric Quality Indicators (PDIs) - Measures that can be used with hospital inpatient discharge data to identify potential quality of care problems. Focus on children and reflect both quality of care inside hospitals and identify potentially avoidable hospitalizations among children. The PDIs were developed after comprehensive literature review, analysis of ICD-9-CM codes, implementation of risk adjustment, and empirical analysis. For more information see: Quality Indicators

Prevention Quality Indicators (PQIs) - Measures that can be used with hospital inpatient discharge data to identify "ambulatory care sensitive conditions." These are conditions for which good outpatient care can potentially prevent the need for hospitalization or for which early intervention can prevent complications or more severe disease. The PQIs were developed after comprehensive literature review, analysis of ICD-9-CM codes, implementation of risk adjustment, and empirical analysis. For more information see: Quality Indicators

Race/ethnicity - Racial/ethnic designation for the patient as listed in the medical record. Because not every State provides this information, race/ethnicity is not available for every State or for the national estimates.

Rank Order - Diagnoses or procedures ranked by such factors as number of discharges, charges, or in-hospital mortality rate. For example, you can rank hospital stays in the U.S. from the most common diagnosis to the least common, or you can rank hospital stays from the most expensive to the least expensive.

Rates of discharges - Calculated using national population estimates that correspond to the year of HCUP data. The population estimates are taking from the HCUP Methods Report: "Population Denominator Data for Use with the HCUP Databases," which is available from the HCUP Methods Series.

Readmission - A subsequent hospital admission within a certain period of time following an original admission (or index stay). Readmissions in HCUPnet are 30-day readmissions, thus, the discharge date for the index stay must occur between January and November to allow a 30-day follow-up period for all index stays. Readmissions can be into the same or a different hospital. See "Methods #45; Calculating Readmissions for HCUPnet" HTML.

Readmission rate - Defined as [the number of stays with a readmission] divided by [the total number of stays from Jan-Nov] for that condition or procedure. Specifically,
the number of stays with at least one subsequent hospital stay within 30 days
the total number of hospital stays between January and NovemberSee "Methods #45; Calculating Readmissions for HCUPnet" HTML.

Region - The four U.S. regions defined by the Bureau of the Census: Northeast, Midwest, South, and West. Northeast is defined as Connecticut, Maine, Massachusetts, New Hampshire, New Jersey, New York, Pennsylvania, Rhode Island, and Vermont. Midwest is defined as Illinois, Indiana, Iowa, Kansas, Minnesota, Missouri, Michigan, Nebraska, North Dakota, Ohio, South Dakota and Wisconsin. South is defined as Alabama, Arkansas, Delaware, District of Columbia, Florida, Georgia, Kentucky, Maryland, Mississippi, Louisiana, Tennessee, North Carolina, Oklahoma, South Carolina, Texas, Virginia, West Virginia. West is defined as Alaska, Arizona, California, Colorado, Hawaii, Idaho, Montana, Nevada, New Mexico, Oregon, Utah, Washington, Wyoming.

Related Conditions and Procedures - This option allows you to select a principal diagnosis or procedure and examine related diagnoses or procedures. If you choose a specific principal diagnosis, you can then list procedures associated with it, for example, "What procedures are received by patients with acute myocardial infarction?" You can also examine the secondary diagnoses associated with that principal diagnosis, for example, "What secondary diagnoses also appear on the discharge record for a principally diagnosed acute myocardial infarction hospital stay?" If you choose a specific principal procedure, you can then list diagnoses that appear on the same discharge record, for example, "For patients receiving total hip replacement, what diagnoses appear on the discharge record?" You can also look at other procedures associated with it, for example, "What additional procedures are received by patients who have a hip replacement?” Please note, with ICD-10-CM CCSR queries, related conditions include non-default CCSRs associated with a principal diagnosis.

Safety-net status - Safety-net hospitals have the highest number of Medicaid or uninsured stays (top quartile)

Secondary diagnoses - Additional diagnoses that appear on the discharge record with the first-listed or principal diagnosis you chose, for example, "What secondary diagnoses also appear on the discharge record for a principally diagnosed acute myocardial infarction hospital stay?"

Secondary procedures - Additional procedures that appear on the discharge record with the first-listed or principal procedure you chose, for example, "What additional procedures also appear on the discharge record for patients whose principal procedure was a blood transfusion?"

Teaching status - Whether the hospital in which the stay occurred is a teaching or a non-teaching hospital. A hospital is considered to be a teaching hospital if the American Hospital Association (AHA) Annual Survey indicates it has an AMA-approved residency program, is a member of the Council of Teaching Hospitals (COTH), or has a ratio of full-time equivalent interns and residents to beds of .25 or higher.

Trauma center - A hospital equipped to provide comprehensive emergency medical services to patients suffering traumatic injuries 24 hours a day, 365 days per year. Hospitals are designated by a state or local authority or verified by the American College of Surgeons. Typically, Level I centers offer a full range of specialists/equipment 24 hours a day, have surgical residency programs, have a program of research, are a referral resource for communities in nearby regions, and have at least 1200 admissions a year. Level II centers offer comprehensive trauma care in collaboration with Level I center, essential specialties/equipment available 24 hours a day, but are not required to have teaching and research. Level III centers have resources for resuscitation, surgery and intensive care units (but do not have the full availability of specialists), and have transfer agreements with Level I and II centers. The data source for this information is the Trauma Information Exchange Program (TIEP), a program of the American Trauma Society in collaboration with the Johns Hopkins Center for Injury Research and Policy, funded by the Centers for Disease Control and Prevention. The TIEP inventory of trauma centers identifies all trauma centers in the U.S.

Trends - Tables and graphs with trends over time.

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