The Administrative Simplification provisions of the Health Insurance Portability and Accountability Act of 1996 (HIPAA) mandated the adoption of a standard unique identifier for health care providers. The National Plan and Provider Enumeration System (NPPES) collects identifying information on health care providers and assigns each a unique National Provider Identifier (NPI).
These are NPI's identified from Inpatient Billing data. Some hospitals bill for multiple entities under different NPI's, while others bill for multiple components (Hospital, Distinct Part Units) under the same NPI.
A hospital may operate multiple entities. Sometimes these may include facilities or services that operate under the same provider number. Such Associated NPIs are identified by the hospital.
NPIs reported for each associated provider are taken from a NPPES file containing FOIA-disclosable data for health care providers. These data were reported by providers and providers are responsible for accuracy. Note that it is sometimes difficult to discern the NPI for an associated entity due to inadequate or inaccurate information.
For more information see the NPPES website and the CMS NPI website.