This variable is contained in the following files: Carrier (Fee-for-Service)
Short SAS Name
PRFNPI
SAS Name
PRF_PHYSN_NPI

The National Provider Identifier (NPI) assigned to the performing provider.

Comments
: 

Effective May 2007, the NPI became the national standard identifier for covered health care providers. NPIs replaced the legacy numbers (UPINs, PINs, etc.) on the standard HIPPA claim transactions.

The UPIN is almost never populated after 2009.

Source: NCH