NIH NEDS: HCUP Emergency Dept. Sample Explained

NEDS is the Nationwide Emergency Department Sample, a database run through the Healthcare Cost and Utilization Project (HCUP) and sponsored by the Agency for Healthcare Research and Quality (AHRQ), not by the National Institutes of Health. People searching “NIH NEDS” are almost always looking for this dataset. It is bought, not applied for: a purchaser completes a short data use agreement training, signs the HCUP data use agreement, and orders the files through AHRQ’s Central Distributor. This guide follows the official HCUP pages, as described on 2026-10-29.

Is “NIH NEDS” an NIH program?

No. The HCUP NEDS overview page describes the NEDS as part of a family of databases and software tools developed for HCUP, through a Federal-State-Industry partnership sponsored by AHRQ. AHRQ is a separate agency of the U.S. Department of Health and Human Services. Searchers who add “NIH” are likely thinking of the federal health research system generally. For NIH grant mechanisms themselves, see CASRAI’s overview of NIH grants. The purchase path below runs through AHRQ.

What NEDS is and who runs it

AHRQ’s page calls the NEDS “the largest all-payer emergency department (ED) database in the United States,” built to yield national estimates of hospital-owned ED visits. As described on the overview page:

Scale: about 34 million unweighted ED visits each year, which the weights turn into an estimate of roughly over 144 million visits.
Sources: it is drawn from the State Inpatient Databases (SID), which cover patients seen in the ED and then admitted to the same hospital, and the State Emergency Department Databases (SEDD), which cover treat-and-release visits and transfers to another hospital.
Coverage: releases are available for data years 2006 through 2024.
Annual files: each release is a calendar-year file, except data year 2015, which was split into two parts because of the switch from ICD-9-CM to ICD-10-CM/PCS coding.

Requirements to obtain NEDS

The official pages do not describe eligibility categories such as institution type or career stage. They set requirements that apply to everyone who touches the data. The HCUP page on data use agreements states: “All purchasers and users of HCUP data must complete the HCUP Data Use Agreement (DUA) Training Course and sign an HCUP DUA before use and/or receipt of the data.” The NEDS overview adds that this covers data purchasers and collaborators alike, and that the agreement to read and sign is the Data Use Agreement for Nationwide Databases. For the general concept, see CASRAI’s entry on the data use agreement (DUA).

The training course takes about 15 minutes, according to the HCUP DUA page. Completing it produces a certification code that the page says “will be required to purchase or gain access to HCUP data.” Purchasers also take on additional responsibilities, which they acknowledge in the Central Distributor application.

What the files contain

The NEDS has four discharge-level files and one hospital-level file, per the overview page:

Core File: records for all ED visits in the SID and SEDD from the sample of hospitals in participating States and the District of Columbia, whether or not the visit ended in admission.
Supplemental ED File: additional information on patients treated in the ED and not admitted directly to the hospital, taken from the SEDD.
Supplemental Inpatient File: inpatient-stay elements such as total charges, length of stay and procedure codes, for patients admitted to the same hospital.
Diagnosis and Procedure Groups File: groupings of ICD-10-CM/PCS diagnoses and procedures produced by HCUP software tools, available beginning with data year 2018.
Hospital Weights file: one record per sampled hospital-owned ED, with the weights used for national and regional estimates.

The Core File links to the two supplemental files through the record identifier KEY_ED. AHRQ also notes that procedures on inpatient records may have been performed in the ED, but there is currently no way to verify that, which matters for any analysis of ED procedures.

What changed in the 2024 release

The overview page lists changes tied to a change in the states available to participate. For treat-and-release visits, the ED charge element (TOTCHG_ED_2024) carries two separate adjustments for the Western and Midwest regions. For visits that end in admission to the same hospital, the inpatient charge element (TOTCHG_IP) is not included and the ED charge element is set to missing. AHRQ warns that these changes may make some comparisons across years more difficult.

Application and purchase steps

The HCUP Central Distributor page describes three stages:

Create an online HCUP Central Distributor account.
Complete the DUA training and sign the HCUP DUA; the signed documents are submitted through the distributor’s online system, CDORS.
Purchase the NEDS release through CDORS.

Questions about purchasing go to the HCUP Central Distributor at [email protected]. The distributor page says participating data organizations set the price of their data, that some offer reduced pricing for AHRQ grantees, students and non-profits, and that current prices appear in CDORS.

Pre-purchase checklist: hardware and software

The overview page lists what you need to load and analyze the files: the password supplied by the Central Distributor, a hard drive with at least 300 GB free, a third-party zip utility such as 7-Zip (the files are compressed and encrypted with 7-Zip and delivered as CSV via secure download), and SAS, SPSS, Stata or similar analysis software. Loading programs for SAS, SPSS and Stata are on the NEDS Database Documentation page.

Typical timeline phases

The official pages publish no processing times, so this sequence shows order, not duration:

Scoping: decide which data years and files your question needs, using the Introduction to the NEDS for the year you plan to use.
Training and agreement: complete the roughly 15-minute DUA course and keep the certification code.
Account and purchase: create the Central Distributor account, submit signed documents and buy through CDORS.
Delivery and setup: download the encrypted CSV files, check disk space, and load them with the supplied programs.
Analysis: apply the Hospital Weights file for national or regional estimates.

Common mistakes

These follow directly from the stated requirements:

Looking for an NIH application. There is no application to NIH; the route is the HCUP Central Distributor.
Treating collaborators as exempt. The overview page says all HCUP data users, including collaborators, must complete the training and sign the agreement.
Buying before the certification code exists. The code is required to purchase or gain access.
Underestimating storage. The overview page calls the data set extremely large and requires at least 300 GB free.
Pooling years without checking the changes. The 2015 split and the 2024 charge-element changes both affect comparisons.
Using unweighted counts as national figures. The weights file exists to produce national and regional estimates.

Related programs and resources

Resource	Relationship to NEDS	Source
HCUP	The AHRQ-sponsored family of databases and software tools that includes NEDS	NEDS overview page
State Inpatient Databases (SID)	Supply NEDS records for ED patients later admitted to the same hospital	NEDS overview page
State Emergency Department Databases (SEDD)	Supply NEDS records for treat-and-release visits and transfers	NEDS overview page
HCUP Central Distributor (CDORS)	The online system for accounts, signed agreements and purchases	Central Distributor page
HCUP DUA Training Course	Required before purchase or use; yields the certification code	HCUP DUA page

For other restricted-access data routes, compare CASRAI’s guides to the CMS data use agreement process and to PhysioNet credentialed access. For analysis context, see secondary data analysis and the Elixhauser Comorbidity Index, a comorbidity measure applied to hospital discharge data.

Frequently asked questions

Is NEDS the same as the NIH Enterprise Directory?

No. The NIH Enterprise Directory (NED) is a different system with a similar acronym; NEDS is the HCUP emergency department database described here.

Who runs the Nationwide Emergency Department Sample?

It is part of HCUP, developed through a Federal-State-Industry partnership sponsored by AHRQ.

What do I have to do before I can buy NEDS?

Complete the HCUP DUA training course, sign the HCUP DUA, and create a Central Distributor account. The certification code from the training is required to purchase.

How much does NEDS cost?

The official pages do not state a NEDS price. The distributor page says participating data organizations set prices and that current prices are shown in CDORS.