The Healthcare Cost and Utilization Project (HCUP) Nationwide Readmissions Database (NRD) is a unique and powerful database designed to support various types of analyses of national readmission rates for all payers and the uninsured. The NRD includes discharges for patients with and without repeat hospital visits in a year and those who have died in the hospital. Repeat stays may or may not be related. The criteria to determine the relationship between hospital admissions is left to the analyst using the NRD. This database addresses a large gap in health care data - the lack of nationally representative information on hospital readmissions for all ages. Outcomes of interest include national readmission rates, reasons for returning to the hospital for care, and the hospital costs for discharges with and without readmissions. Unweighted, the NRD contains data from approximately 18 million discharges each year. Weighted, it estimates roughly 35 million discharges. 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.

The NRD is drawn from HCUP State Inpatient Databases (SID) containing verified patient linkage numbers that can be used to track a person across hospitals within a State, while adhering to strict privacy guidelines. The NRD is not designed to support regional, State-, or hospital-specific readmission analyses.

The NRD contains more than 100 clinical and non-clinical data elements provided in a hospital discharge abstract. Data elements include but are not limited to: diagnoses, procedures, patient demographics (e.g., sex, age), expected source of payer, regardless of expected payer, including but not limited to Medicare, Medicaid, private insurance, self-pay, or those billed as ‘no charge, discharge month, quarter, and year, total charges, length of stay, and data elements essential to readmission analyses. The NIS excludes data elements that could directly or indirectly identify individuals.

Restricted access data files are available with a data use agreement and brief online security training.

The National Hospital Ambulatory Medical Care Survey (NHAMCS), conducted by the National Center for Health Statistics (NCHS), collects annual data on visits to emergency departments to describe patterns of utilization and provision of ambulatory care delivery in the United States. Data are collected from nonfederal, general, and short-stay hospitals from all 50 U.S. states and the District of Columbia, and are used to develop nationally representative estimates.

The data include counts and rates of emergency department visits from 2016-2022 for the 10 leading primary diagnoses and reasons for visit, stratified by selected patient and hospital characteristics. Rankings for the 10 leading categories were identified using weighted data from 2022 and were then assessed in prior years.

The National Hospital Care Survey (NHCS) collects data on patient care in hospital-based settings to describe patterns of health care delivery and utilization in the United States. Settings currently include inpatient and emergency departments (ED). Additionally, the NHCS contributes data that may inform public health emergencies as the survey is designed to capture emerging diseases and viruses that require hospitalizations, including COVID-19 encounters. The 2020 - 2023 NHCS are not yet fully operational so it is important to note that these data are not nationally representative.

The data are from 26 hospitals submitting inpatient and 26 hospitals submitting ED Uniform Bill (UB)-04 administrative claims from March 18, 2020-December 26, 2023. Even though the data are not nationally representative, they can provide insight on the impact of COVID-19 on various types of hospitals throughout the country. This information is not available in other hospital reporting systems. The NHCS data from these hospitals can show results by a combination of indicators related to COVID-19, such as length of inpatient stay, in-hospital mortality, comorbidities, and intubation or ventilator use. NHCS data allow for reporting on patient conditions and treatments within the hospital over time.

These data include counts and rates of emergency department visits from 2016-2022 for selected primary diagnoses and reasons for visit, stratified by selected patient and hospital characteristics.
Search, visualize, and download these and other estimates from over 120 health topics with the NCHS Data Query System (DQS), available from: https://www.cdc.gov/nchs/dataquery/index.htm.

HCUPnet is an online data tool based on data from the Healthcare Cost and Utilization Project (HCUP).

The data tool provides healthcare statistics and information for hospital inpatient and emergency department settings, as well as population-based healthcare data on counties. Users are able to query HCUP data to access detailed or summary statistics on inpatient stays and emergency department visits by patient, hospital, and encounter characteristics. Users are also able to generate tables and graphs on national and regional statistics and trends for community hospitals in the United States.

The National Hospital Ambulatory Medical Care Survey (NHAMCS) has been fielded annually since 1992 to collect data on the utilization and provision of ambulatory care services in hospital emergency and outpatient departments. Data collection from hospital-based ambulatory surgery centers began in 2009. And between 2010 and 2012 NHAMCS gathered data on visits to freestanding ambulatory surgery centers. In 2018, the survey began focusing on just the ambulatory visits made to emergency departments.
Each emergency department is randomly assigned to a 4-week reporting period. During this period, data for a systematic random sample of visits are recorded by Census interviewers using a computerized Patient Record Form. Data are obtained on patient characteristics such as age, sex, race, and ethnicity, and visit characteristics such as patient’s reason for visit, provider’s diagnosis, services ordered or provided, and treatments, including medication therapy. In addition, data about the facility are collected as part of a survey induction interview.

2023 Respiratory Virus Response - NSSP Emergency Department Visits - COVID-19, Flu, RSV, Combined


For additional information, please see: Companion Guide: NSSP Emergency Department Data on Respiratory Illness

List of footnotes, notes, and source information for The National Hospital Ambulatory Medical Care Survey (NHAMCS). Each row of this dataset contains the accompanying text for a footnote found in NHAMCS dataset. The footnote lookup can be merged onto any NHAMCS dataset using, DATASET_SHORT_NAME, FN_ID, FN_TYPE, and FN_TEXT.

SOURCE: National Center for Health Statistics CDC, The National Hospital Ambulatory Medical Care Survey (NHAMCS)

The Healthcare Cost and Utilization Project (HCUP) Nationwide Emergency Department Sample (NEDS) is the largest all-payer emergency department (ED) database in the United States. yielding national estimates of hospital-owned ED visits. Unweighted, it contains data from over 30 million ED visits each year. Weighted, it estimates roughly 145 million ED visits nationally. 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.

Sampled from the HCUP State Inpatient Databases (SID) and State Emergency Department Databases (SEDD), the HCUP NEDS can be used to create national and regional estimates of ED care. The SID contain information on patients initially seen in the ED and subsequently admitted to the same hospital. The SEDD capture information on ED visits that do not result in an admission (i.e., treat-and-release visits and transfers to another hospital). 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.

The NEDS contain information about geographic characteristics, hospital characteristics, patient characteristics, and the nature of visits (e.g., common reasons for ED visits, including injuries). The NEDS contains 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). It includes ED charge information for over 85% of patients, regardless of expected payer, including but not limited to Medicare, Medicaid, private insurance, self-pay, or those billed as ‘no charge’. The NEDS excludes data elements that could directly or indirectly identify individuals, hospitals, or states.Restricted access data files are available with a data use agreement and brief online security training.

2023 Respiratory Virus Response - NSSP Emergency Department Visits - COVID-19, Flu, RSV, Combined – by Demographic Category

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