The Nationwide Readmissions Database (NRD) is a set of inpatient databases in the HCUP family designed for readmission analyses. These HCUP databases are created by AHRQ through a Federal-State-Industry partnership.
The following links provide data elements descriptions for the Nationwide Readmissions Database (NRD).
Data element descriptions explain how the data element is coded in the HCUP databases, and what are the uniform values. The descriptions are cumulative across all years of the NRD. Please note the following:
Not all data elements in the NRD are uniformly coded across States.
Not all data elements are available each year.
For certain data elements such as, but not limited to, total charges (TOTCHG), more than one percent of NRD records have missing values. Users are advised to review frequencies for all data elements planned for use in their analysis and to consider analytic methods for dealing with missing data. The HCUP Methods Series Report #2015-01 (PDF file, 871 KB) provides guidance on alternative approaches to handling missing data.
As a result of the introduction of ICD-10-CM/PCS1 on October 1, 2015 (quarter 4 of 2015 and the start of fiscal year 2016), the United States transitioned from using ICD-9-CM to ICD-10-CM/PCS code sets for reporting clinical diagnoses and inpatient procedures. Beginning with the quarter 4 of 2015 (2015 Q4), the names of diagnosis- and procedure-related data elements in the NRD Core File start with the prefix "I10_" to identify the coding scheme. The coding change in 2015 also is signaled by a change in the NRD file structure:
The 2015 NRD included nine months of data with ICD-9-CM coding and three months of data with ICD-10-CM/PCS coding because of the mid-year change in diagnosis and procedure coding. The 2015 NRD files had a very different structure than other years and were split into two parts based on the diagnosis and procedure coding system.
Beginning with data year 2016, the NRD is an annual, calendar year file with diagnosis and procedure codes reported using only the ICD-10-CM/PCS coding system. Therefore, the file structure is similar to the file structure of the NRD in data years 2014 and prior years.
Beginning 2015 Q4, data elements derived from the AHRQ software tools based on ICD-10-CM/PCS diagnosis and/or procedure codes are not available on the NRD except for the Clinical Classifications Software Refined (CCSR) for ICD-10-CM diagnoses, which is available beginning in data year 2018. Users interested in applying additional AHRQ software tools to the NRD that include ICD-10-CM/PCS-coded data may do so by downloading the respective tool(s) from the HCUP Tools & Software section of the HCUP User Support (HCUP-US) website. The Tools Loading tutorial is available to users interested in applying the AHRQ software tools at www.hcup-us.ahrq.gov/tech_assist/tutorials.jsp.
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
All NRD data elements are listed in alphabetical order below, showing the NRD file location for years other than 2015 and for 2015. For a description of how HCUP data elements are coded, and uniform values, check the corresponding boxes below and then click the "View Description of Data Elements".
Internet Citation: NRD Description of Data Elements.
Healthcare Cost and Utilization Project (HCUP). November 2020.
Agency for Healthcare Research and Quality, Rockville, MD. www.hcup-us.ahrq.gov/db/nation/nrd/nrddde.jsp.