Where the data comes from

Patientary doesn’t maintain its own registry of providers or diagnosis codes — it’s a reference layer over three public, authoritative government and standards-body sources. This page states exactly what each lookup returns, how derived fields are computed, and what we won’t do with the data.

Provider data — CMS NPPES

Every NPI lookup and provider search queries the CMS National Plan and Provider Enumeration System (NPPES) live, on demand. We do not store a bulk copy of the registry and serve it stale — each request hits NPPES directly, and the response is cached for a short period (minutes, not days) purely to absorb repeat traffic and stay within upstream rate limits. If NPPES is unreachable, the API returns an upstream_unavailable error, never a cached-forever or synthesized record.

Diagnosis codes — ICD-10-CM

The code set is the official annual CMS ICD-10-CM release, loaded in full: 97,584 codes, of which 74,260 are billable (leaf-level, valid for claim submission) and 23,324 are chapter/category headers (not billable on their own). Three fields are derived rather than stored verbatim in the source file:

• Chapter— assigned from the fixed CMS chapter code-range table (22 chapters, e.g. chapter IV covers endocrine, nutritional and metabolic diseases, E00–E89). We compute it from the code, we don’t re-guess it.
• Billable— read directly from the CMS “valid for submission” flag in the official release. We don’t infer billability from code length or formatting.
• Parent — derived by walking up the code hierarchy within the same release (e.g. E11.9’s parent is the E11 header), so crosswalk and code-family results always reflect the current release, not a hand-maintained tree.

Provider taxonomy — NUCC

Specialty codes come from the official NUCC Health Care Provider Taxonomy code set (roughly 880 codes), used to describe a provider’s specialty and to power taxonomy search and NPI-to-specialty lookups.

The honesty contract

This is the rule every endpoint follows, without exception: real data or an explicit failure — never a fabricated result. If a provider doesn’t exist, the API returns not_found, not a plausible-looking placeholder. If an upstream source is down, it returns upstream_unavailable or upstream_timeout, not a stale or synthesized answer. Every response also carries a disclaimer field so this contract travels with the data, not just this page.

Not affiliated, not advice

Patientary is an independent reference tool. We are not affiliated with, endorsed by, or operated by the Centers for Medicare & Medicaid Services (CMS), the National Uniform Claim Committee (NUCC), or any other standards body whose public data we query. Patientary is an informational reference tool built on public data (CMS NPPES and the official ICD-10-CM release). It is not medical, coding, legal or billing advice, and code assignment is the responsibility of a qualified professional. Always verify against the primary source before you bill or file.

Questions about a specific result

If a lookup looks wrong, verify it directly against the primary source before you rely on it — NPPES NPI Registry search for providers, or the current CMS ICD-10-CM release for codes. To report a discrepancy in how we surface the data, email support [at] patientary.com. See also our API & MCP docs for the machine-readable version of this same attribution.