A number of MPIES Registry data elements have been or could be linked to claims records.
Several additional variables are in the process of being added to the MPIES file, including the practitioner's social security number, business tax identification number, and the full street address of the practice site.
The accuracy of the MPIES Registry data has been investigated by indirect verification--primarily checks of face validity and of logical consistency among related or repeated data elements (Adamache, Cyr, and Merrill, 1994).
The UPIN reporting rate is the proportion of physician-services claims or allowed charges accounted for by UPINs listed on the MPIES Registry.
In fact, even in 1992, UPINs were still being phased in by some carriers, so that counts from the MPIES Registry are unreliable for assessing change in the size of the Medicare physician population before and after physician payment reform.