HOSP_NRD is a HCUP hospital identifier created specifically for the Nationwide Readmissions Database (NRD). Its purpose is to identify inpatient records that are associated with the same hospital. HOSP_NRD does not link to other HCUP databases or to external databases. In contrast to the HCUP hospital identifier HOSPID, HOSP_NRD does not identify the state or region of the hospital.

The values of HOSP_NRD differ from year to year. An individual hospital cannot be followed across data years.

For consistency across states, HCUP defines hospitals in accordance with the American Hospital Association Annual Survey of Hospitals. During HCUP data processing, the data source's identification of the hospital is reconciled with the identification of the hospital in the AHA Annual Survey. For detailed information about this linking process, see the special report on HCUP Hospital Identifiers.