Overview of the Nationwide Readmissions Database (NRD) The Nationwide Readmissions Database (NRD) is part of a family of databases and software tools developed for the Healthcare Cost and Utilization Project (HCUP). The NRD is a unique and powerful database designed to support various types of analyses of national readmission rates for all patients, regardless of the expected payer for the hospital stay. This database addresses a large gap in healthcare data - the lack of nationally representative information on hospital readmissions for all ages. 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.
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BEGINNING WITH DATA YEAR 2016, THE NRD CONTAINS A FULL YEAR OF ICD-10-CM/PCS CODES
Beginning with data year 2016, the NRD includes a full calendar year of data with diagnosis and procedure codes reported using the ICD-10-CM/PCS1 coding system. The file structure is similar to the file structure of the NRD in data years 2014 and prior years. THE 2015 NRD CONTAINS ICD-9-CM AND ICD-10-CM/PCS CODES On October 1, 2015, hospital administrative data began using ICD-10-CM/PCS, so the first nine months of 2015 contain ICD-9-CM codes and the last three months contain ICD-10-CM/PCS codes. Data elements and data structure for the 2015 NRD have changed. Trends based on diagnoses or procedures will be affected. Data elements derived from AHRQ software tools are not available for ICD-10-CM/PCS data on the NRD except for the Clinical Classifications Software Refined (CCSR) for ICD-10-CM diagnoses, which is available beginning data year 2018. |
1 ICD-9-CM: International Classification of Diseases, Ninth Revision, Clinical Modification. ICD-10-CM/PCS: International Classification of Diseases, Tenth Revision, Clinical Modification/Procedure Coding System.
This page provides an overview of the NRD. For more details, see NRD Database Documentation and the Introduction to the NRD, 2010-2018 (PDF file, 1.0 MB; HTML). Contents:
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The NRD is drawn from the HCUP State Inpatient Databases (SID) and can be used to create estimates of national readmission rates for all patients, regardless of the expected payer for the hospital. The 2018 NRD was constructed from 28 States with reliable, verified patient linkage numbers in the SID that could be used to track the patient across hospitals within a State, while adhering to strict privacy guidelines. Key features of the 2018 NRD include:
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Beginning with data year 2016, the NRD is a calendar year file that includes diagnoses and procedures coded using only ICD-10-CM/PCS. The file structure is similar to the file structure of the NRD in data years 2014 and prior years. For 2015 data, because of the transition to ICD-10-CM/PCS on October 1, 2015, data elements related to diagnoses and procedures are included in files that are split into two parts. Nine months of the 2015 data with ICD-9-CM codes (discharges from January 1, 2015 - September 30, 2015) are in one set of files labeled Q1-Q3. Three months of 2015 data with ICD-10-CM/PCS codes (discharges from October 1, 2015 - December 31, 2015) are in a separate set of files labeled Q4. More information about the changes to the HCUP databases for ICD-10-CM/PCS and use of data across the two coding systems may be found on the HCUP-US website under ICD-10-CM/PCS Resources. |
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The NRD contains clinical and nonclinical variables that support readmission analyses, with safeguards to protect the privacy of individual patients, physicians, and hospitals. There is no data element identifying whether sequential inpatient stays are related or unrelated. The criteria to determine the relationship between hospital admissions is left to the analyst using the NRD. The NRD is comprised of more than 100 clinical and nonclinical variables for each hospital stay, including:
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As a uniform, multi-State weighted database, the NRD promotes comparative studies of healthcare services and supports healthcare policy and research on a variety of topics, including:
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The NRD for data years 2010-2018 are available for purchase online through the HCUP Central Distributor. All HCUP data users, including data purchasers and collaborators, must complete the online HCUP Data Use Agreement Training Tool, and read and sign the Data Use Agreement for Nationwide Databases (PDF file, 99 KB; HTML). Questions regarding purchasing databases can be directed to the HCUP Central Distributor:
E-mail: HCUPDistributor@AHRQ.gov
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The NRD is distributed as comma-separated value (CSV) files delivered via secure digital download from the HCUP Central Distributor. The files are compressed and encrypted with SecureZIP® from PKWARE. To load and analyze the NRD data on a computer, you users will need the following:
Please note the following based on the software you plan to use:
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Internet Citation: NRD Overview. Healthcare Cost and Utilization Project (HCUP). December 2020. Agency for Healthcare Research and Quality, Rockville, MD. www.hcup-us.ahrq.gov/nrdoverview.jsp. |
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Last modified 12/1/20 |