The Nationwide Readmissions Database is part of the Healthcare Cost and Utilization Project (HCUP) family of databases. The NRD is derived from the HCUP State Inpatient Databases (SID), and aims to provide nationally represenative data to support hospital readmission analyses. The NRD includes all-payer inpatient discharges from HCUP partner community hospitals in the SID which have verifiable patient linkage numbers. These synthetic linkage numbers allow analysts to track patients across hospital stays, while maintaining patient privacy. The NRD contains over 14 million discharge records per data year from about 85% of SID discharges from participating states. The 122 data elements in the NRD include diagnostic and procedure codes, and hospital characteristics. The data cannot be used to track readmissions across states or across data years or used for state-, facility-, or physician-level analyses.