NPI registry status
Active
2026 NPPES data Internal Medicine Physician NPI 1154616035 M.D.
Verify on CMS → Stephen Yau, M.D.
Internal Medicine Physician in Portland, Oregon.
This profile is drawn from the federal National Provider Identifier Registry (CMS NPPES), which lists more than 7 million U.S. healthcare providers - including 172,737 in Internal Medicine Physician, and covers specialty classification, practice address, and Medicare Part D prescribing data when reported. According to CMS, every field reflects the provider's official federal registration, see our methodology.
Federal data, no proprietary rating.
We show these CMS records as-is - no composite score, no star rating, no editorial opinion layered on top.
Prescribing volume
725
Medicare Part D claims · 103 beneficiaries · Internal Medicine Physician avg: 3K
Generic prescribing
0%
generic claims · 78% brand-name · higher generic rates reduce patient out-of-pocket costs
Industry payments
$412.9K
350 payments · CMS Open Payments (Sunshine Act)
Source: CMS Medicare Part D Prescriber Public Use File, 2023
What the federal data shows
Stephen Yau, M.D. filed 725 Medicare Part D claims in 2023 as an Internal Medicine Physician in Portland, Oregon, prescribing 0% generic.
- 725
- Part D claims, 2023
- 0%
- generic prescribing
- Likely
- board-certified (heuristic)
- ≥71st
- pct by Part D claim volume (lower-bound band)
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.
Stephen Yau, M.D.'s Medicare Part D volume vs every U.S. prescriber
Total Medicare Part D claims, 2023, across all CMS prescribers nationally
725 ≥ 71st percentile 71% of 1,370,886 prescribers are in lower value bands
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.
The percentile is a conservative 100-claim band: it counts only prescribers in lower claim-volume bands. Medicare Part D claim volume is activity context, not a quality measure or recommendation. See methodology § corpus placement.
Source CMS Medicare Part D Prescriber Public Use File · 2023
✓
Board certification likely (heuristic, not verified)
Stephen Yau, 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 Stephen Yau, M.D.?
Quality data not reportedPrimary specialty
Internal Medicine Physician
Medicare Part D claims
725 73% vs specialty avg
Specialty distribution in Oregon
How Internal Medicine Physician compares to other specialties among Oregon providers
Board certification
Not published by CMS
CMS does not publish a per-provider board-certification field in NPPES. PlainDoctor does not have a reliable per-specialty certification rate to show for Internal Medicine Physician. Verify directly:
How MIPS and board certification work
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).
Stephen Yau, M.D. appears in the CMS NPPES registry as an Internal Medicine Physician provider holding M.D. credentials at 9427 SW BARNES RD STE 296, Portland, OR, 97225, with a listed phone of (503) 297-3778. NPI 1154616035 was issued on 06/18/2011.
Medicare Part D records for calendar year 2023 show 725 prescription claims written by this provider, covering 103 Medicare beneficiaries and totaling roughly $931K in drug spend, split 78% brand-name and 0% generic by claim count.
Internal Medicine Physician is a high-volume specialty nationwide, with 172,737 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
Provider Details
| NPI | 1154616035 |
|---|---|
| Specialty | Internal Medicine Physician |
| Credentials | M.D. |
| Gender | Male |
| NPI Issued | 06/18/2011 |
Hospital and facility affiliations
Facilities where Stephen Yau, 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.
Peacehealth
Vancouver, WA
Affiliations sourced from CMS Doctors and Clinicians National Downloadable File; hospital ratings from CMS Hospital General Information dataset (cross-referenced by facility name + state).
Industry payments received (2024) - CMS Open Payments transparency data
The federal Physician Payments Sunshine Act (part of the Affordable Care Act) requires drug and medical-device manufacturers + group purchasing organizations to publicly report payments and other transfers of value to physicians and teaching hospitals. The data below covers 2024 for Stephen Yau, M.D.. Source: openpaymentsdata.cms.gov.
Total received
$412.9K
Largest payer
GENZYME CORPORATION
Most common payment type
Travel and Lodging
Industry payments are not necessarily indicators of bias, they include research funding, consulting fees for evidence-based work, royalties for inventions, food at conferences, and similar items. The disclosure exists for transparency. Read our methodology for how we interpret this data.
Brand vs generic prescribing mix · Brand-heavy
Stephen Yau, M.D. - brand share 78.0%
Internal Medicine Physician average
78% brand-name claims vs 0% generic, on 725 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.
725
Total Claims
$931K
Total Drug Cost
103
Medicare Beneficiaries
Prescribing Breakdown
- 30-Day Fills
- 939
- Total Day Supply
- 26,734
- Brand vs Generic
- 78% brand / 0% generic
- Brand Drug Cost
- $908K
- Antibiotic Claims
- 11
Patient Demographics
- Average Patient Age
- 72.5 years
- Avg HCC Risk Score
- 1.68
- Gender Split
- 59% female / 41% male
Top Prescribed Drugs (Medicare Part D)
Top drugs by claim count for calendar year 2023. Based on Medicare Part D data only.
What Stephen Yau, M.D. prescribes most
Top Medicare Part D drugs by claim count, 2023
- Trelegy Ellipta
Trelegy Ellipta
136 claims
- Albuterol Sulfate …
Albuterol Sulfate Hfa
62 claims
- Montelukast Sodium 52
Montelukast Sodium
52 claims
- Fluticasone-Salmet… 46
Fluticasone-Salmeterol
46 claims
- Spiriva Handihaler 42
Spiriva Handihaler
42 claims
- Dupixent Pen 38
Dupixent Pen
38 claims
- Breztri Aerosphere 36
Breztri Aerosphere
36 claims
- Ofev 33
Ofev
33 claims
| Drug | Claims |
|---|---|
| Trelegy Ellipta Fluticasone/Umeclidin/Vilanter | 136 |
| Albuterol Sulfate Hfa Albuterol Sulfate | 62 |
| Montelukast Sodium | 52 |
| Fluticasone-Salmeterol Fluticasone Propion/Salmeterol | 46 |
| Spiriva Handihaler Tiotropium Bromide | 42 |
| Dupixent Pen Dupilumab | 38 |
| Breztri Aerosphere Budesonide/Glycopyr/Formoterol | 36 |
| Ofev Nintedanib Esylate | 33 |
| Breo Ellipta Fluticasone/Vilanterol | 29 |
| Advair Diskus Fluticasone Propion/Salmeterol | 25 |
* 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 Stephen Yau, M.D. fits within the Internal Medicine Physician landscape nationally.
172,737
Internal Medicine Physician Providers in US
56
States with Internal Medicine Physician
2,716
Avg Claims per Provider
Stephen Yau, M.D.'s 725 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 Yau.
Dr. Charmaine Clarisse Abalos
M.D.
Medford, OR
Dr. Soraya Abbassian
M.D.
Portland, OR
Dr. Nicholas Abbott
M.D.
Tualatin, OR
Dr. Mohamed Abdel Khalek
M.D
Roseburg, OR
Dr. Amged Abdelaziz
MD
Portland, OR
Compare Internal Medicine Physician nationally: see state-by-state distribution →
Before you book an appointment
Use this federal record as your verification checklist, not as a recommendation.
- Confirm the NPI record is current in the official CMS registry, providers update their own NPPES details, and moves can lag. Verify this NPI
- Check the active license and any disciplinary history with the Oregon medical board, federal registration is not a license check. Credential verification guide
- Weigh a second option: compare this provider with a nearby Internal Medicine Physician peer on Medicare volume and prescribing patterns. Compare providers
Medicare Part D and MIPS figures describe practice patterns in federal programs only, they are not quality ratings, and PlainDoctor does not rate, rank, or recommend providers.
Healthcare Guides
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Medical Specialties Explained
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Frequently Asked Questions
What is Stephen Yau, M.D.'s specialty? ▼
Stephen Yau, M.D. specializes in Internal Medicine Physician and practices in Portland, Oregon. Credentials: M.D..
How much does Stephen Yau, M.D. prescribe under Medicare Part D? ▼
In 2023, Stephen Yau, M.D. wrote 725 Medicare Part D claims totaling $931K in drug costs for 103 beneficiaries.
Where is Stephen Yau, M.D. located? ▼
Stephen Yau, M.D. is located at 9427 SW BARNES RD STE 296, Portland, OR, 97225. Phone: (503) 297-3778.
What is Stephen Yau, M.D.'s NPI number? ▼
Stephen Yau, M.D.'s National Provider Identifier (NPI) is 1154616035, issued on 06/18/2011.
Does Stephen Yau, M.D. prescribe more brand-name or generic drugs? ▼
Stephen Yau, M.D.'s prescribing is 78% brand-name and 0% generic drugs by claim count, with $908K in brand drug costs.
How many Internal Medicine Physician providers are there in the US? ▼
There are 172,737 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 Stephen Yau, M.D. prescribe most often? ▼
Based on 2023 Medicare Part D data, Stephen Yau, M.D.'s most frequently prescribed drugs include Trelegy Ellipta, Albuterol Sulfate Hfa, Montelukast Sodium. This reflects Medicare Part D prescriptions only and does not include commercial insurance or other payer types.
Does Stephen Yau, M.D. accept Medicare? ▼
Stephen Yau, M.D. appears in CMS Medicare data with 725 Part D claims and 103 Medicare beneficiaries in 2023. Contact the provider's office directly to confirm current Medicare enrollment and accepted plans.
How can I verify Stephen Yau, M.D.'s credentials? ▼
Stephen Yau, M.D.'s NPI is 1154616035 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
View source datasets and methodology notes
- 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
Every figure on PlainDoctor is rendered directly from the federal CMS NPPES registry, Medicare Part D, MIPS, and Open Payments records, no number is typed in by an editor. See our editorial standards & corrections policy, the methodology behind these numbers, or report a data error. Data current as of May 2026.