NPI registry status
Active
2026 NPPES data Internal Medicine Physician NPI 1265601553 M.D.
Verify on CMS → Stephen Chen, M.D.
Internal Medicine Physician in Oakland, California.
This profile is drawn from the federal National Provider Identifier Registry (CMS NPPES), which lists more than 7 million U.S. healthcare providers - including 174,792 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
966
Medicare Part D claims · 190 beneficiaries · Internal Medicine Physician avg: 3K
Generic prescribing
85%
generic claims · 15% brand-name · higher generic rates reduce patient out-of-pocket costs
Source: CMS Medicare Part D Prescriber Public Use File, 2024
What the federal data shows
Stephen Chen, M.D. filed 966 Medicare Part D claims in 2024 as an Internal Medicine Physician in Oakland, California, prescribing 85% generic.
- 966
- Part D claims, 2024
- 85%
- generic prescribing
- Likely
- board-certified (heuristic)
- ≥74th
- 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.
Federal trust snapshot
What official records show about Stephen Chen, M.D.
Federal records show an active NPI with Medicare Part D prescribing activity — verifiable registry data, not a proprietary rating.
- Verified
NPI registry status
Active listing in the CMS National Provider Identifier Registry (NPI 1265601553), first enumerated 02/21/2008.
Source: CMS NPPES
- Reported
Medicare Part D participation
Filed 966 Medicare Part D prescription claims in the 2023 CMS public use file — indicates active Medicare prescribing participation.
Source: CMS Part D Prescriber PUF
- Reported
Board certification signal
Heuristic suggests board-certified status based on ABMS-eligible specialty taxonomy plus active CMS participation signals — not a direct ABMS verification.
- Reported
Hospital affiliations
1 CMS Care Compare hospital affiliation on record — practice footprint from the Doctors and Clinicians file.
Source: CMS Care Compare
- State context
State board disciplinary context
California statewide board action statistics are published annually — these figures describe aggregate state activity, not Stephen Chen, M.D.'s individual license status. Verify directly with the state medical board.
Source: MBC annual report 2023
- Not in federal data
Individual sanction lookup
PlainDoctor does not publish per-provider disciplinary determinations. Confirm current license and any individual actions through the state medical board or FSMB verification service.
Source: State medical board / FSMB
This trust snapshot summarizes only what appears in federal CMS/NPPES public records. It is not a composite score, star rating, patient review, or clinical recommendation. PlainDoctor never fabricates reviews or AggregateRating schema.
CMS NPPES provider registry desk
NPI 1265601553 · Internal Medicine Physician
NPI-10 · ENUM-MID · TAX-MEGA · RX-LIGHT · BOOK-MID · PHOTO-ENUM
- NPI-10 1265601553
- ENUM-MID 2008
- TAX-MEGA 175K Internal Medicine
- RX-LIGHT 966
- BOOK-MID 20,403 in California
- PHOTO-ENUM Ambreen Hasan · 2008
Stephen Chen, M.D.'s Medicare Part D volume vs every U.S. prescriber
Total Medicare Part D claims, 2024, across all CMS prescribers nationally
966 ≥ 74th percentile 74% of 1,416,883 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 · 2024
✓
Board certification likely (heuristic, not verified)
Stephen Chen, 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 Chen, M.D.?
Quality data not reportedPrimary specialty
Internal Medicine Physician
Medicare Part D claims
966 65% vs specialty avg
Specialty distribution in California
How Internal Medicine Physician compares to other specialties among California 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).
Practice Address
Provider Details
| NPI | 1265601553 |
|---|---|
| Specialty | Internal Medicine Physician |
| Credentials | M.D. |
| Gender | Male |
| NPI Issued | 02/21/2008 |
Hospital and facility affiliations
Facilities where Stephen Chen, 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.
Permanente Medical Group Inc
Modesto, CA
Affiliations sourced from CMS Doctors and Clinicians National Downloadable File; hospital ratings from CMS Hospital General Information dataset (cross-referenced by facility name + state).
License & disciplinary context - California MBC 2023 annual report
Aggregate state board data only, NOT a determination of any individual provider's status. The figures below describe statewide disciplinary activity across all ~150K California medical licensees in 2023 - they are NOT specific to Stephen Chen, M.D.. To verify Stephen Chen, M.D.'s current license status, search the MBC public license lookup directly, or check the Federation of State Medical Boards (FSMB) verification service.
576
Total board actions, California 2023
Across 556 cases
3.84
Actions per 1,000 licensees
California statewide rate
probation
Most common action type
186 cases
MBC publishes annual disciplinary statistics as part of public-record reporting under each state's Administrative Procedure Act. See the full breakdown by action type and year on the California disciplinary trends page. Cross-checked against FSMB U.S. Medical Regulatory Trends.
Brand vs generic prescribing mix · Typical
Stephen Chen, M.D. - brand share 15.0%
Internal Medicine Physician average
15% brand-name claims vs 85% generic, on 966 2024 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 2024.
966
Total Claims
$129K
Total Drug Cost
190
Medicare Beneficiaries
Prescribing Breakdown
- 30-Day Fills
- 1,331.167
- Total Day Supply
- 35,652
- Brand vs Generic
- 15% brand / 85% generic
- Brand Drug Cost
- $97K
- Generic Drug Cost
- $33K
- Opioid Claims
- 458 (47.4% rate)
Patient Demographics
- Average Patient Age
- 75.0 years
- Avg HCC Risk Score
- 2.88
- Gender Split
- 60% female / 40% male
- Age Distribution
- <65: 21, 65-74: 62, 75-84: 81, 85+: 26
Top Prescribed Drugs (Medicare Part D)
Top drugs by claim count for calendar year 2024. Based on Medicare Part D data only.
What Stephen Chen, M.D. prescribes most
Top Medicare Part D drugs by claim count, 2024
- Hydrocodone-Acetam…
Hydrocodone-Acetaminophen
119 claims
- Oxycontin
Oxycontin
99 claims
- Dexamethasone
Dexamethasone
76 claims
- Oxycodone-Acetamin…
Oxycodone-Acetaminophen
63 claims
- Trazodone Hcl
Trazodone Hcl
62 claims
- Oxycodone Hcl
Oxycodone Hcl
55 claims
- Mirtazapine
Mirtazapine
52 claims
- Gabapentin 43
Gabapentin
43 claims
| Drug | Claims |
|---|---|
| Hydrocodone-Acetaminophen Hydrocodone/Acetaminophen | 119 |
| Oxycontin Oxycodone Hcl | 99 |
| Dexamethasone | 76 |
| Oxycodone-Acetaminophen Oxycodone Hcl/Acetaminophen | 63 |
| Trazodone Hcl | 62 |
| Oxycodone Hcl | 55 |
| Mirtazapine | 52 |
| Gabapentin | 43 |
| Morphine Sulfate Er Morphine Sulfate | 37 |
| Fentanyl | 28 |
* 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 Chen, M.D. fits within the Internal Medicine Physician landscape nationally.
174,792
Internal Medicine Physician Providers in US
56
States with Internal Medicine Physician
2,785
Avg Claims per Provider
Stephen Chen, M.D.'s 966 claims are below the specialty average of 2,785.
Nationwide Internal Medicine Physician peers with similar MIPS or enrollment year
Two federal-record peer sets for Chen, both outside California so the neighborhoods are not geographic containment.
Same NPPES enumeration year (2008)
Same-specialty clinicians who entered the NPI registry in the same calendar year, outside this state.
Nearby Internal Medicine Physician Providers in California
Other clinicians with the same primary specialty enrolled in California, drawn from the same CMS NPPES roster as Chen.
One of 20,403 Internal Medicine Physician providers enrolled in California, 5 are shown here.
Dr. Jacob Aaron
MD
San Francisco, CA
Dr. Alistair Aaronson
MD
Stanford, CA
Dr. Jose Abad.
MD
Sacramento, CA
Dr. Donna Abare
MD
Oakland, CA
Marce Abare
Scotts Valley, CA
Compare Internal Medicine Physician nationally: see state-by-state distribution →
Frequently Asked Questions
What is Stephen Chen, M.D.'s specialty? ▼
Stephen Chen, M.D. specializes in Internal Medicine Physician and practices in Oakland, California. Credentials: M.D..
How much does Stephen Chen, M.D. prescribe under Medicare Part D? ▼
In 2024, Stephen Chen, M.D. wrote 966 Medicare Part D claims totaling $129K in drug costs for 190 beneficiaries.
Where is Stephen Chen, M.D. located? ▼
Stephen Chen, M.D. is located at 1800 HARRISON ST, Oakland, CA, 94612. Phone: (510) 625-6262.
What is Stephen Chen, M.D.'s NPI number? ▼
Stephen Chen, M.D.'s National Provider Identifier (NPI) is 1265601553, issued on 02/21/2008.
Does Stephen Chen, M.D. prescribe more brand-name or generic drugs? ▼
Stephen Chen, M.D.'s prescribing is 15% brand-name and 85% generic drugs by claim count, with $97K in brand drug costs.
Does Stephen Chen, M.D. prescribe opioids? ▼
Yes, Stephen Chen, M.D. had 458 opioid claims in 2024 with an opioid prescribing rate of 47.4%.
How many Internal Medicine Physician providers are there in the US? ▼
There are 174,792 Internal Medicine Physician providers across 56 states in the US. The average Internal Medicine Physician provider writes 2,785 Medicare Part D claims per year.
What drugs does Stephen Chen, M.D. prescribe most often? ▼
Based on 2024 Medicare Part D data, Stephen Chen, M.D.'s most frequently prescribed drugs include Hydrocodone-Acetaminophen, Oxycontin, Dexamethasone. This reflects Medicare Part D prescriptions only and does not include commercial insurance or other payer types.
Does Stephen Chen, M.D. accept Medicare? ▼
Stephen Chen, M.D. appears in CMS Medicare data with 966 Part D claims and 190 Medicare beneficiaries in 2024. Contact the provider's office directly to confirm current Medicare enrollment and accepted plans.
How can I verify Stephen Chen, M.D.'s credentials? ▼
Stephen Chen, M.D.'s NPI is 1265601553 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 (2024). 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 August 2026 (NPPES) / 2024 (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 August 2026.