NPI registry status
Active
2026 NPPES data Vascular Surgery Physician NPI 1356363543 M.D.
Verify on CMS → Andrew Ahn, M.D.
Vascular Surgery Physician in Pomona, 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 4,215 in Vascular Surgery 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
80
Medicare Part D claims · 12 beneficiaries · Vascular Surgery Physician avg: 205
Generic prescribing
75%
generic claims · 25% brand-name · higher generic rates reduce patient out-of-pocket costs
Source: CMS Medicare Part D Prescriber Public Use File, 2023
Compiled from official public sources by the PlainDoctor editorial team.
What the federal data shows
Andrew Ahn, M.D. filed 80 Medicare Part D claims in 2023 as a Vascular Surgery Physician in Pomona, California, prescribing 75% generic.
- 80
- Part D claims, 2023
- 75%
- generic prescribing
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.
Andrew Ahn, M.D.'s Medicare Part D volume vs every U.S. prescriber
Total Medicare Part D claims, 2023, across all CMS prescribers nationally
80 0th percentile higher than 0% of 1,370,886 prescribers
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-eligible specialty (heuristic, not verified)
Andrew Ahn, M.D. practices in an ABMS-board-eligible specialty but we don't have enough CMS-participation signals to confirm active board-certified status. Consult CertificationMatters.org (the official ABMS public lookup).
What does the federal data show about Andrew Ahn, M.D.?
Quality data not reportedPrimary specialty
Vascular Surgery Physician
Medicare Part D claims
80 61% vs specialty avg
Specialty distribution in California
How Vascular Surgery 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 Vascular Surgery 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).
Andrew Ahn, M.D. appears in the CMS NPPES registry as a Vascular Surgery Physician provider holding M.D. credentials at 1900 ROYALTY DR, Pomona, CA, 91767, with a listed phone of (714) 530-0303. NPI 1356363543 was issued on 07/24/2006.
Medicare Part D records for calendar year 2023 show 80 prescription claims written by this provider, covering 12 Medicare beneficiaries and totaling roughly $15K in drug spend, split 25% brand-name and 75% generic by claim count.
Vascular Surgery Physician is a narrow specialty nationwide, with 4,215 enrolled providers across 53 states and an average of 205 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 | 1356363543 |
|---|---|
| Specialty | Vascular Surgery Physician |
| Credentials | M.D. |
| Gender | Male |
| NPI Issued | 07/24/2006 |
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 Andrew Ahn, M.D.. To verify Andrew Ahn, 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 · Above average
Andrew Ahn, M.D. - brand share 25.0%
Vascular Surgery Physician average
25% brand-name claims vs 75% generic, on 80 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.
80
Total Claims
$15K
Total Drug Cost
12
Medicare Beneficiaries
Prescribing Breakdown
- 30-Day Fills
- 155
- Total Day Supply
- 4,049
- Brand vs Generic
- 25% brand / 75% generic
- Brand Drug Cost
- $10K
- Generic Drug Cost
- $5K
- Antibiotic Claims
- 21
Patient Demographics
- Average Patient Age
- 69.6 years
- Avg HCC Risk Score
- 3.75
Top Prescribed Drugs (Medicare Part D)
Top drugs by claim count for calendar year 2023. Based on Medicare Part D data only.
| Drug | Claims |
|---|---|
| Vascepa Icosapent Ethyl | 17 |
* Counts below 11 are suppressed by CMS for patient privacy. Generic names shown where available from CMS Part D data.
Vascular Surgery Physician Overview
How Andrew Ahn, M.D. fits within the Vascular Surgery Physician landscape nationally.
4,215
Vascular Surgery Physician Providers in US
53
States with Vascular Surgery Physician
205
Avg Claims per Provider
Andrew Ahn, M.D.'s 80 claims are below the specialty average of 205.
Nearby Vascular Surgery Physician Providers in California
Other clinicians with the same primary specialty enrolled in California, drawn from the same CMS NPPES roster as Ahn.
Dr. Arad Abadi
MD
Lancaster, CA
Dr. Andrew Abi-Chaker
M.D.
Sherman Oaks, CA
Dr. Ahmed Abou-Zamzam
M.D.
Loma Linda, CA
Dr. Joseph Abu-Dalu
MD
Los Angeles, CA
Dr. Queen Abure
MD
San Francisco, CA
Compare Vascular Surgery 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 California medical board, federal registration is not a license check. Credential verification guide
- Weigh a second option: compare this provider with a nearby Vascular Surgery 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
Learn more about finding, verifying, and understanding healthcare providers.
How to Find a Doctor
Step-by-step guide to choosing a provider
Verify Credentials
Check NPI, board certification & license status
Medical Specialties Explained
Who treats what and how specialties differ
Understanding Medicare Claims Data
What prescribing data reveals about a provider
In-Network vs Out-of-Network
How insurance networks affect your costs
Telehealth Guide
Virtual care options and coverage in 2026
Explore California
Frequently Asked Questions
What is Andrew Ahn, M.D.'s specialty? ▼
Andrew Ahn, M.D. specializes in Vascular Surgery Physician and practices in Pomona, California. Credentials: M.D..
How much does Andrew Ahn, M.D. prescribe under Medicare Part D? ▼
In 2023, Andrew Ahn, M.D. wrote 80 Medicare Part D claims totaling $15K in drug costs for 12 beneficiaries.
Where is Andrew Ahn, M.D. located? ▼
Andrew Ahn, M.D. is located at 1900 ROYALTY DR, Pomona, CA, 91767. Phone: (714) 530-0303.
What is Andrew Ahn, M.D.'s NPI number? ▼
Andrew Ahn, M.D.'s National Provider Identifier (NPI) is 1356363543, issued on 07/24/2006.
Does Andrew Ahn, M.D. prescribe more brand-name or generic drugs? ▼
Andrew Ahn, M.D.'s prescribing is 25% brand-name and 75% generic drugs by claim count, with $10K in brand drug costs.
How many Vascular Surgery Physician providers are there in the US? ▼
There are 4,215 Vascular Surgery Physician providers across 53 states in the US. The average Vascular Surgery Physician provider writes 205 Medicare Part D claims per year.
What drugs does Andrew Ahn, M.D. prescribe most often? ▼
Based on 2023 Medicare Part D data, Andrew Ahn, M.D.'s most frequently prescribed drugs include Vascepa. This reflects Medicare Part D prescriptions only and does not include commercial insurance or other payer types.
Does Andrew Ahn, M.D. accept Medicare? ▼
Andrew Ahn, M.D. appears in CMS Medicare data with 80 Part D claims and 12 Medicare beneficiaries in 2023. Contact the provider's office directly to confirm current Medicare enrollment and accepted plans.
How can I verify Andrew Ahn, M.D.'s credentials? ▼
Andrew Ahn, M.D.'s NPI is 1356363543 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
Compiled from official public sources by the PlainDoctor editorial team.