Are NPI numbers public?

Yes. NPI numbers are public federal identifiers in CMS NPPES. This page shows the public NPPES facts Fonteum has for NPI 1598949521: provider name, entity type, taxonomy, practice location, enumeration date, last-updated date, and source snapshot date. It does not include patient information.

What does the NPI record show for Matthew Chang?

Matthew Chang (NPI 1598949521) appears in CMS NPPES as gastroenterologist in Palo Alto, CA. NPPES is administrative identity data submitted to CMS by providers and organizations; this page displays the source snapshot date as 2026-05-06.

Does this page assign a provider score?

No derived score is assigned on this provider page. NPPES is an identity registry; when a CMS QPP MIPS value is available, Fonteum displays that public CMS value with its source, and absence of a MIPS value is not a quality signal.

Does no exclusion match amount to a clearance?

Coverage is indeterminate, so this page makes no negative exclusion determination. This is not a clearance; check the current issuing-agency lists.

Where does the provider data come from?

The identity fields come from CMS NPPES. Additional sections appear only when a public source has a matching row, such as CMS PECOS, CMS Open Payments, Medicare Part D, CMS QPP MIPS, OIG LEIE, or state Medicaid exclusion lists. Source and date metadata appears where the response supplies it; unavailable dates are labeled.

Matthew Chang — NPI 1598949521: exclusion status

Name: Provider record — NPI 1598949521 (Matthew Chang)
Creator: Fonteum
License: https://www.usa.gov/government-works

Built on the authoritative federal record

The primary sources, named on every page.

These are the federal agencies whose public datasets Fonteum ingests and attributes — the issuing authorities, not customers or partners. Every figure on the site links back to one of them.

CMS
HHS-OIG
HRSA
FDA
NLM
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Census
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Reproducible by design

Published figures name their source and date.

Source and date

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Daily observations

The platform records table row counts daily. Those observations detect local drift; they do not imply that an upstream publisher released or Fonteum ingested new data that day.

Named medical review

Reviewed by Jennifer Montecillo, MD, medical reviewer. Non-practicing medical reviewer.

Read the full provenance and attestation methodology →

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Matthew Chang — NPI 1598949521: exclusion status — Fonteum

Cross-source identity

Sources that publish this NPI

National Provider Identifier 1598949521 appears in the source rows shown below. Sources that do not publish NPI use their own identifiers and are not treated as deterministic NPI matches. Chips show response-supplied dates when available; otherwise they are labeled date unavailable.

NPPESOPEN PAYMENTS

Federal sources carrying NPI 1598949521
Federal source	Key	What it provides	Source & date
CMS NPPES	NPI 1598949521	Registry identity — gastroenterologist, taxonomy 207RG0100X	Source:CMS NPPESSnapshot 2026-05-06
CMS Open Payments	NPI 1598949521	1 industry-payment records, 2024	Source:CMS Open PaymentsSnapshot PY2024
CMS Medicare Part D	NPI 1598949521	10 drugs prescribed, 2024	Source:CMS Part DSnapshot DY2024

Industry payments

Open Payments received

Payments and transfers of value this clinician received from drug and device manufacturers, disclosed under the Physician Payments Sunshine Act. A payment is a disclosure, not a judgment.

$24

Total received

Payment records

Manufacturers

2024-08-13

Latest payment

Top categories

Largest payment categories by dollars
Nature of payment	Amount	Records
Food and Beverage	$24	1

Top manufacturers

Largest paying manufacturers by dollars
Manufacturer	Amount	Records
Abbvie Inc.	$24	1

Source:CMS Open PaymentsSnapshot PY2024National Open Payments analysis →

Prescribing

Medicare Part D prescribing

Prescriptions written under Medicare Part D, aggregated by drug across the program. Totals reflect claims paid, not patients treated.

502

Part D claims

$176,215

Total drug cost

Distinct drugs

315

Beneficiaries (≥)

Highest-cost drugs prescribed
Drug	Claims	Drug cost
Xifaxan(Rifaximin)	48	$158,905
Ursodiol	35	$7,034
Gavilyte-C(Peg3350/Sod Sulf,Bicarb,Cl/Kcl)	239	$5,485
Lactulose	17	$2,048
Pantoprazole Sodium	64	$1,014

Beneficiary counts below 11 are suppressed by CMS — the total shown is a lower bound.

Source:CMS Medicare Part DSnapshot DY2024

Ownership & affiliations

Who owns, operates, or is affiliated with this provider

Chain membership, ownership, and operating relationships from federal records — each one backed by a government source row. Most individual clinicians have none; owners and organizations carry more.

Ownership and affiliation records
Relationship	Entity	Source
← pays	Abbvie Inc. (IL)	cms open payments

Full record card →Entity JSON

Matthew Chang

Public NPPES answers

Are NPI numbers public?

What does the NPI record show for Matthew Chang?

Does this page assign a provider score?

Does no exclusion match amount to a clearance?

Where does the provider data come from?

Sources that publish this NPI

Open Payments received

Top categories

Top manufacturers

Medicare Part D prescribing

MIPS quality score

Standing

Who owns, operates, or is affiliated with this provider

Retained versions for this record

Matthew Chang

Public NPPES answers

Are NPI numbers public?

What does the NPI record show for Matthew Chang?

Data-use and correction resources.

Does this page assign a provider score?

Does no exclusion match amount to a clearance?

Where does the provider data come from?

Sources that publish this NPI

Open Payments received

Top categories

Top manufacturers

Medicare Part D prescribing

MIPS quality score

Standing

Who owns, operates, or is affiliated with this provider

Retained versions for this record

Context for this record