2026 NPPES data Internal Medicine Physician NPI 1629259916 M.D.
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TOM CHAU, M.D.

Internal Medicine Physician in PORTLAND, Oregon. CMS National Plan and Provider Enumeration System profile including specialty classification, practice address, and Medicare prescribing data when reported.

Federal data — no proprietary rating. PlainDoctor publishes the actual CMS NPPES and Medicare records — NPI registration, specialty, practice location, and prescribing data — without a composite score or editorial opinion on top. Every field traces to a federal source.
Prescribing volume
2K
Medicare Part D claims · 278 beneficiaries · Internal Medicine Physician avg: 3K
Generic prescribing
88%
generic claims · 12% brand-name · higher generic rates reduce patient out-of-pocket costs

What the federal data shows

TOM CHAU, M.D. filed 1,992 Medicare Part D claims in 2023 as a Internal Medicine Physician in PORTLAND, Oregon, prescribing 88% generic.

2K
Part D claims, 2023
88%
generic prescribing
Likely
board-certified (heuristic)

Every figure on this page comes straight from federal CMS records (NPPES, Medicare Part D, MIPS, Open Payments) — no proprietary rating or editorial opinion is applied.

TOM CHAU, M.D.'s Medicare Part D volume vs every U.S. prescriber

Total Medicare Part D claims, 2023 — across all CMS prescribers nationally

1,992 Top 16% higher than 84% of 1,370,886 prescribers

0–200: 670,926 prescribers (49%). Below this entry. 200–400: 182,923 prescribers (13%). Below this entry. 400–600: 90,619 prescribers (7%). Below this entry. 600–800: 56,224 prescribers (4%). Below this entry. 800–1,000: 40,919 prescribers (3%). Below this entry. 1,000–1,200: 31,827 prescribers (2%). Below this entry. 1,200–1,400: 26,224 prescribers (2%). Below this entry. 1,400–1,600: 21,710 prescribers (2%). Below this entry. 1,600–1,800: 19,072 prescribers (1%). Below this entry. 1,800–2,000: 16,451 prescribers (1%). This entry sits in this band. 2,000–2,200: 213,991 prescribers (16%). Above this entry. This provider 0 2K+ every Part D prescriber (claims/yr), bucketed by value

Each bar is a band; taller bars hold more prescribers. The dashed line + filled bar mark this entry. Hover or tap any bar for its full count, share, and where it sits relative to this entry.

Source CMS Medicare Part D Prescriber Public Use File · 2023

Board certification likely (heuristic — not verified)

TOM CHAU, M.D. practices in an ABMS-board-eligible specialty and shows active CMS Medicare participation + 1 hospital affiliation — signals consistent with board-certified status. For verified board certification, see CertificationMatters.org (the official ABMS public lookup).

What does the federal data show about TOM CHAU, M.D.?

Quality data not reported

NPI registry status

Active

Issued 11/15/2007

NPI 1629259916

Primary specialty

Internal Medicine Physician

High-volume

172,858 US NPIs in this specialty

Medicare Part D claims

1,992 27% vs specialty avg

2023 prescription claims

Specialty avg: 2,716

Specialty distribution in Oregon

How Internal Medicine Physician compares to other specialties among Oregon providers

Oregon providers

Internal Medicine Physician share within Oregon

1. Internal Medicine Physician42%2. Internal medicine21%3. Family medicine17%4. Surgical12%5. Pediatric8%
Internal Medicine Physician share within Oregon

Specialty board-certification context

Estimated specialty board-certified rate — Internal Medicine Physician (ABMS / AOA reference)

Quality data not reported
Est. board-certified rate
78%
Internal Medicine Physician ABMS/AOA estimate

Est. board-certified rate (Internal Medicine Physician) — ABMS / AOA estimate

0%100%78%
Est. board-certified rate (Internal Medicine Physician) — ABMS / AOA estimate

The Merit-based Incentive Payment System (MIPS) scores providers 0–100 across four performance categories: Quality, Cost, Promoting Interoperability, and Improvement Activities, weighted under 42 CFR §414.1380. Reporting is voluntary for many small practices, so absence of a MIPS score is not a quality signal.

Board certification through an ABMS or AOA member board signals voluntary post-licensure examination plus continuous Maintenance of Certification cycles. Verify any individual provider's status through certificationmatters.org (ABMS) or osteopathic.org (AOA).

TOM CHAU, M.D. appears in the CMS NPPES registry as a Internal Medicine Physician provider holding M.D. credentials at 9205 SW BARNES RD, PORTLAND, OR, 97225, with a listed phone of (503) 216-2621. NPI 1629259916 was issued on 11/15/2007. Because NPPES data is self-reported by the provider and refreshed monthly, the address, phone, and specialty reflect what CHAU most recently submitted to CMS rather than a vetted directory listing, which is why patients should always confirm the practice is still at this location before scheduling.

Medicare Part D records for calendar year 2023 show 1,992 prescription claims written by this provider, covering 278 Medicare beneficiaries and totaling roughly $210K in drug spend, split 12% brand-name and 88% generic by claim count, with an opioid prescribing rate of 6.4%. These figures capture only Medicare Part D — commercial insurance, Medicaid, and cash-pay prescriptions are not included, and any drug-beneficiary cell under 11 is suppressed by CMS for patient privacy.

Internal Medicine Physician is a high-volume specialty nationwide, with 172,858 enrolled providers across 56 states and an average of 2,716 Part D claims per prescriber, so the context for interpreting these metrics differs meaningfully from a primary-care baseline. Important: PlainDoctor is a directory of publicly available government data, not medical advice, a malpractice database, or a quality rating. Inclusion here does not imply a recommendation, and absence of complaints or sanctions on this page does not mean none exist — always verify credentials through the NPPES NPI Registry, your state medical board, and the ABMS or AOA before making healthcare decisions.

Practice Address

9205 SW BARNES RD
PORTLAND, OR 97225

Provider Details

NPI 1629259916
Specialty Internal Medicine Physician
Credentials M.D.
Gender Male
NPI Issued 11/15/2007

Hospital and facility affiliations

Facilities where TOM CHAU, M.D. bills Medicare from. Star ratings (1-5) are CMS Hospital Compare's "Hospital overall rating" — a composite of mortality, readmission, patient experience, safety, timely care, and efficient use of medical imaging measures. Source: CMS Care Compare.

PROVIDENCE HEALTH AND SERVICES OREGON
PORTLAND, OR

Affiliations sourced from CMS Doctors and Clinicians National Downloadable File; hospital ratings from CMS Hospital General Information dataset (cross-referenced by facility name + state).

Brand vs generic prescribing mix · Typical

TOM CHAU, M.D. — brand share 12.0%
Specialty average (est.)

12% brand-name claims vs 88% generic, on 1,992 2023 Medicare Part D claims.

The federal Medicare Part D Generic Dispensing Rate national benchmark sits near 90% generic / 10% brand for primary-care prescribers, per CMS Office of the Actuary 2024 estimates. Higher brand share is common in specialty prescribing where generic equivalents are not available.

Medicare Part D Prescribing Data

CMS Medicare Part D prescriber-level data for calendar year 2023.

1,992
Total Claims
$210K
Total Drug Cost
278
Medicare Beneficiaries

Prescribing Breakdown

30-Day Fills
4,486
Total Day Supply
132,008
Brand vs Generic
12% brand / 88% generic
Brand Drug Cost
$160K
Generic Drug Cost
$49K
Opioid Claims
128 (6.4% rate)
Antibiotic Claims
27

Patient Demographics

Average Patient Age
75.1 years
Avg HCC Risk Score
1.59
Gender Split
51% female / 49% male
Age Distribution
<65: 28, 65-74: 91, 75-84: 113, 85+: 46

Top Prescribed Drugs (Medicare Part D)

Top drugs by claim count for calendar year 2023. Based on Medicare Part D data only.

What TOM CHAU, M.D. prescribes most

Top Medicare Part D drugs by claim count, 2023

claims
Source CMS Medicare Part D Prescriber Public Use File As of 2023
Drug Claims
Rosuvastatin Calcium
104
Indapamide
96
Metformin Hcl Er
Metformin Hcl
80
Atorvastatin Calcium
73
Levothyroxine Sodium
72
Gabapentin
47
Irbesartan
46
Alfuzosin Hcl Er
Alfuzosin Hcl
45
Amlodipine-Olmesartan
Amlodipine Bes/Olmesartan Med
45
Tamsulosin Hcl
43

* Counts below 11 are suppressed by CMS for patient privacy. Generic names shown where available from CMS Part D data.

Internal Medicine Physician Overview

How TOM CHAU, M.D. fits within the Internal Medicine Physician landscape nationally.

172,858
Internal Medicine Physician Providers in US
56
States with Internal Medicine Physician
2,716
Avg Claims per Provider

TOM CHAU, M.D.'s 1,992 claims are below the specialty average of 2,716.

Nearby Internal Medicine Physician Providers in Oregon

Other clinicians with the same primary specialty enrolled in Oregon, drawn from the same CMS NPPES roster as CHAU.

Compare Internal Medicine Physician nationally: see state-by-state distribution →

Frequently Asked Questions

What is TOM CHAU, M.D.'s specialty?
TOM CHAU, M.D. specializes in Internal Medicine Physician and practices in PORTLAND, Oregon. Credentials: M.D..
How much does TOM CHAU, M.D. prescribe under Medicare Part D?
In 2023, TOM CHAU, M.D. wrote 1,992 Medicare Part D claims totaling $210K in drug costs for 278 beneficiaries.
Where is TOM CHAU, M.D. located?
TOM CHAU, M.D. is located at 9205 SW BARNES RD, PORTLAND, OR, 97225. Phone: (503) 216-2621.
What is TOM CHAU, M.D.'s NPI number?
TOM CHAU, M.D.'s National Provider Identifier (NPI) is 1629259916, issued on 11/15/2007.
Does TOM CHAU, M.D. prescribe more brand-name or generic drugs?
TOM CHAU, M.D.'s prescribing is 12% brand-name and 88% generic drugs by claim count, with $160K in brand drug costs.
Does TOM CHAU, M.D. prescribe opioids?
Yes, TOM CHAU, M.D. had 128 opioid claims in 2023 with an opioid prescribing rate of 6.4%.
How many Internal Medicine Physician providers are there in the US?
There are 172,858 Internal Medicine Physician providers across 56 states in the US. The average Internal Medicine Physician provider writes 2,716 Medicare Part D claims per year.
What drugs does TOM CHAU, M.D. prescribe most often?
Based on 2023 Medicare Part D data, TOM CHAU, M.D.'s most frequently prescribed drugs include Rosuvastatin Calcium, Indapamide, Metformin Hcl Er. This reflects Medicare Part D prescriptions only and does not include commercial insurance or other payer types.
Does TOM CHAU, M.D. accept Medicare?
TOM CHAU, M.D. appears in CMS Medicare data with 1,992 Part D claims and 278 Medicare beneficiaries in 2023. Contact the provider's office directly to confirm current Medicare enrollment and accepted plans.
How can I verify TOM CHAU, M.D.'s credentials?
TOM CHAU, M.D.'s NPI is 1629259916 with credentials M.D.. You can verify this through the NPPES NPI Registry, check state medical board records, and confirm board certification through the ABMS or AOA.

Data Sources

Provider Directory
CMS National Plan and Provider Enumeration System (NPPES), download.cms.gov/nppes, updated monthly. Contains NPI, specialty, credentials, and practice location.
Specialty Classification
NUCC Health Care Provider Taxonomy (nucc.org), the industry standard for classifying provider specialties in Medicare and Medicaid billing.
Prescribing Data
CMS Medicare Part D Prescriber Public Use File (2023). Includes claims, drug costs, beneficiaries, and opioid prescribing rates.
Limitations
Provider data is self-reported to CMS. Prescribing data reflects Medicare Part D only and does not include commercial insurance, Medicaid, or cash prescriptions. Claims below 11 beneficiaries are suppressed by CMS for privacy.

See our complete data methodology for details on how we collect and process government data.

Data as of April 2026 (NPPES) / 2023 (Medicare Part D). Source: Centers for Medicare & Medicaid Services (CMS).

Disclaimer: Data from CMS NPPES and Medicare Part D. PlainDoctor does not rate or rank providers. Provider information is self-reported and may not be current. Always verify information directly with the provider. About · Methodology