NPI registry status
Active
2026 NPPES data Internal Medicine Physician NPI 1821030305 M.D.
Verify on CMS → An Pang Chieng, M.D.
Internal Medicine Physician in Los Angeles, 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 172,858 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
6K
Medicare Part D claims · 430 beneficiaries · Internal Medicine Physician avg: 3K
Generic prescribing
84%
generic claims · 15% brand-name · higher generic rates reduce patient out-of-pocket costs
Industry payments
$312.38
13 payments · CMS Open Payments (Sunshine Act)
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
An Pang Chieng, M.D. filed 5,758 Medicare Part D claims in 2023 as a Internal Medicine Physician in Los Angeles, California, prescribing 84% generic.
- 6K
- Part D claims, 2023
- 84%
- generic prescribing
- $312.38
- industry payments (Sunshine Act)
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.
An Pang Chieng, M.D.'s Medicare Part D volume vs every U.S. prescriber
Total Medicare Part D claims, 2023, across all CMS prescribers nationally
5,758 Top 5% higher than 95% 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)
An Pang Chieng, 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 An Pang Chieng, M.D.?
Quality data not reportedPrimary specialty
Internal Medicine Physician
Medicare Part D claims
5,758 112% 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).
An Pang Chieng, M.D. appears in the CMS NPPES registry as a Internal Medicine Physician provider holding M.D. credentials at 3301 N EASTERN AVE, Los Angeles, CA, 90032, with a listed phone of (323) 225-2351. NPI 1821030305 was issued on 06/11/2006.
Medicare Part D records for calendar year 2023 show 5,758 prescription claims written by this provider, covering 430 Medicare beneficiaries and totaling roughly $726K in drug spend, split 15% brand-name and 84% generic by claim count, with an opioid prescribing rate of 2.0%.
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
Provider Details
| NPI | 1821030305 |
|---|---|
| Specialty | Internal Medicine Physician |
| Credentials | M.D. |
| Gender | Male |
| NPI Issued | 06/11/2006 |
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 An Pang Chieng, M.D.. Source: openpaymentsdata.cms.gov.
Total received
$312
Largest payer
Boehringer Ingelheim Pharmaceuticals, Inc.
Most common payment type
Food and Beverage
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.
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 An Pang Chieng, M.D.. To verify An Pang Chieng, 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
An Pang Chieng, M.D. - brand share 15.0%
Internal Medicine Physician average
15% brand-name claims vs 84% generic, on 5,758 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.
5,758
Total Claims
$726K
Total Drug Cost
430
Medicare Beneficiaries
Prescribing Breakdown
- 30-Day Fills
- 10,427
- Total Day Supply
- 300,430
- Brand vs Generic
- 15% brand / 84% generic
- Brand Drug Cost
- $585K
- Generic Drug Cost
- $140K
- Opioid Claims
- 118 (2.0% rate)
- Antibiotic Claims
- 260
Patient Demographics
- Average Patient Age
- 74.0 years
- Avg HCC Risk Score
- 0.99
- Gender Split
- 57% female / 43% male
- Age Distribution
- <65: 40, 65-74: 200, 75-84: 125, 85+: 65
Top Prescribed Drugs (Medicare Part D)
Top drugs by claim count for calendar year 2023. Based on Medicare Part D data only.
What An Pang Chieng, M.D. prescribes most
Top Medicare Part D drugs by claim count, 2023
- Atorvastatin Calcium
Atorvastatin Calcium
458 claims
- Amlodipine Besylate
Amlodipine Besylate
256 claims
- Losartan Potassium 149
Losartan Potassium
149 claims
- Metformin Hcl 146
Metformin Hcl
146 claims
- Levothyroxine Sodium 128
Levothyroxine Sodium
128 claims
- Vascepa 121
Vascepa
121 claims
- Zolpidem Tartrate 109
Zolpidem Tartrate
109 claims
- Rosuvastatin Calcium 105
Rosuvastatin Calcium
105 claims
| Drug | Claims |
|---|---|
| Atorvastatin Calcium | 458 |
| Amlodipine Besylate | 256 |
| Losartan Potassium | 149 |
| Metformin Hcl | 146 |
| Levothyroxine Sodium | 128 |
| Vascepa Icosapent Ethyl | 121 |
| Zolpidem Tartrate | 109 |
| Rosuvastatin Calcium | 105 |
| Omeprazole | 97 |
| Gabapentin | 90 |
* 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 An Pang Chieng, 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
An Pang Chieng, M.D.'s 5,758 claims are above the specialty average of 2,716.
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 Chieng.
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 →
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 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.
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How insurance networks affect your costs
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Frequently Asked Questions
What is An Pang Chieng, M.D.'s specialty? ▼
An Pang Chieng, M.D. specializes in Internal Medicine Physician and practices in Los Angeles, California. Credentials: M.D..
How much does An Pang Chieng, M.D. prescribe under Medicare Part D? ▼
In 2023, An Pang Chieng, M.D. wrote 5,758 Medicare Part D claims totaling $726K in drug costs for 430 beneficiaries.
Where is An Pang Chieng, M.D. located? ▼
An Pang Chieng, M.D. is located at 3301 N EASTERN AVE, Los Angeles, CA, 90032. Phone: (323) 225-2351.
What is An Pang Chieng, M.D.'s NPI number? ▼
An Pang Chieng, M.D.'s National Provider Identifier (NPI) is 1821030305, issued on 06/11/2006.
Does An Pang Chieng, M.D. prescribe more brand-name or generic drugs? ▼
An Pang Chieng, M.D.'s prescribing is 15% brand-name and 84% generic drugs by claim count, with $585K in brand drug costs.
Does An Pang Chieng, M.D. prescribe opioids? ▼
Yes, An Pang Chieng, M.D. had 118 opioid claims in 2023 with an opioid prescribing rate of 2.0%.
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 An Pang Chieng, M.D. prescribe most often? ▼
Based on 2023 Medicare Part D data, An Pang Chieng, M.D.'s most frequently prescribed drugs include Atorvastatin Calcium, Amlodipine Besylate, Losartan Potassium. This reflects Medicare Part D prescriptions only and does not include commercial insurance or other payer types.
Does An Pang Chieng, M.D. accept Medicare? ▼
An Pang Chieng, M.D. appears in CMS Medicare data with 5,758 Part D claims and 430 Medicare beneficiaries in 2023. Contact the provider's office directly to confirm current Medicare enrollment and accepted plans.
How can I verify An Pang Chieng, M.D.'s credentials? ▼
An Pang Chieng, M.D.'s NPI is 1821030305 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.