NPI and taxonomy correctness
Do NDH NPIs pass the Luhn check, exist in NPPES, and agree with NPPES on name and primary specialty? NUCC taxonomy validity + currency.
Headline
100.0000% of 10.9M NDH NPIs pass structural + Luhn validation (2 failing records: 0 structural, 2 Luhn checksum). 2,131 Practitioner/Organization resources carry no us-npi identifier.
2 / 10.9M = 0.00%
unit: count
What this means
Payer data teams
When comparing NDH specialty to NPPES, match against all 15 NPPES taxonomy slots — NOT just slot 1. 15% of NPPES records have their TRUE primary (switch=Y) in a non-slot-1 position, and 6% of NDH Practitioners legitimately match only an NPPES secondary board (dual-specialists).
FHIR implementers
NDH uses TWO specialty code systems on two resources — NUCC on Practitioner.qualification, CMS Medicare Types on PractitionerRole.specialty. A consumer filtering on one won’t interoperate with one using the other. Apply the CMS-published Medicare/NUCC crosswalk (updated quarterly) to bridge.
Regulators
0.79% of NDH NPIs (86K) don’t exist in NPPES at all. 3.49% (379K) are deactivated in NPPES but still live in NDH. NDH’s update cadence lags NPPES by the gap window between releases.
Researchers
99.98% CMS structural validity + 99.83% NUCC validity = the underlying code quality is excellent. The interesting signal is inconsistency BETWEEN code systems for the same practitioner (14% fail the crosswalk check), not invalid codes themselves.
Null hypothesis
NPI structural validity is ≥99.9% and NDH-to-NPPES agreement on name and primary specialty is within documented drift thresholds.
Denominator
All `Practitioner` and `Organization` resources with an NPI identifier.
Data source
CMS NPD bulk export joined against the NPPES monthly full dissemination file (V.2) and the current NUCC quarterly code set.
Notes
H9 only — Practitioner: 7,441,209 OK / 0 invalid structure / 2 Luhn fail / 0 missing. Organization: 3,412,244 OK / 0 invalid / 0 Luhn fail / 2,131 missing. H10 (NPPES existence), H11 (name agreement), H12 (NUCC taxonomy), H13 (specialty agreement) pending the NPPES monthly file + NUCC code set joins.