Oscar L. Chien, M.D.
Geriatric Medicine (Internal Medicine) Physician · San Gabriel, CA
Oscar L. Chien, M.D. is a geriatric medicine (internal medicine) physician with a practice address in San Gabriel, California, and NPI 1679675904, issued on Sep 5, 2006. Check the license (California A54999, as entered in NPPES) on the Medical Board of California; the Medicare figures below come from public CMS files.
- Name
- Oscar L. Chien
- Credential
- M.D.
- Primary taxonomy
- Geriatric Medicine (Internal Medicine) Physician 207RG0300X
- License number
- A54999 CA
Self-reported in NPPES; status is on the state search - Practice location
- 1448 S. San Gabriel BL., San Gabriel, CA 91776
- Phone
- (626) 569-2888
- Enumerated
- Sep 5, 2006
- Record last updated
- Apr 2, 2020 (not updated in 6 years: call before relying on the address or phone)
- Fax
- (626) 569-9929
- Medicaid ID
- 00A549990 CA
- Medicare enrollment
- Enrolled (PECOS I20100902000070); accepts Medicare assignment
- Entity
- Type 1 · individual
8 nearest geriatric medicine (internal medicine) physician records → All 532 in California → Look up another NPI →
Verify Oscar L. Chien in five checks
- 1IdentityNPI record in CMS NPPESNPI lookupConfirmed in NPPES
- 2LicenseActive license and public ordersMedical Board of California
Search for license A54999Check the board - 3Other statesLicenses and actions elsewhereDocInfo (FSMB)Not checked
- 4ExclusionsMedicare and Medicaid bansHHS-OIG exclusion listNot checked
- 5CertificationBoard certificationABMS AOA NCCPA AANPNot checked
10.1 times the Medicare Part D claims of the average geriatric medicine (internal medicine) physician in 2024
43,068 Medicare Part D claims for 1,086 beneficiaries, against an average of 4,246 among the 3,116 providers of this specialty who prescribed in Part D. Brand-name drugs were 23% of claims. 117 claims were for opioids.
Most prescribed
- Atorvastatin Calcium1,782 claims
- Losartan Potassium1,463 claims
- Amlodipine Besylate1,333 claims
- Pantoprazole Sodium1,040 claims
- Jardiance875 claims
- Metoprolol Succinate857 claims
Source: CMS Medicare Part D Prescribers by Provider and Drug, 2024 (data.cms.gov). Part D covers prescriptions for Medicare patients only; drugs with fewer than 11 claims are not published.
The MIPS final score for 2023 (Medicare payment program): 13.2 of 100
The Merit-based Incentive Payment System score is reported for this clinician. Four categories are weighted into the final score; the average among 454,083 clinicians with a measured score was 83.5.
Source: CMS Quality Payment Program, MIPS performance year 2023; category weights for 2023 (qpp.cms.gov).
Industry payments in 2024: $27,480.08
151 payments; by number, the most common kind was food and beverage; the largest payer was Amgen Inc. The 1,004 providers of this specialty with any payment received $1,720.82 on average. Payments are reported by manufacturers, not by the provider, and are not a sign of wrongdoing.
Source: CMS Open Payments, program year 2024 (openpaymentsdata.cms.gov); average among providers of this specialty with at least one payment.
Oscar L. Chien among 532 geriatric medicine (internal medicine) physician records in California
Oscar L. Chien, M.D. is one of 532 geriatric medicine (internal medicine) physician records with a practice address in California. 77% of them appear in a Medicare file (Part D prescribing, MIPS, Open Payments or Medicare group billing); this one does. Its NPI, issued in 2006, is newer than 7% of them.
- NPI issued2006 · 7% of these records are older, 46% newer
- In a Medicare fileYes · 77% of these records are
- In the CMS Doctors and Clinicians fileYes · 51% of these records are
- Graduated1990 · median 1999 among the 271 with a school on file
- Record last updated2020 · 62% of these records were not updated in five years or more
Source: CMS NPPES, file of Aug 9, 2026, every record with primary taxonomy 207RG0300X and a California practice address; Medicare files: CMS Part D Prescribers 2024, MIPS 2023, Open Payments 2024, Doctors and Clinicians (data.cms.gov).
Geriatric Medicine (Internal Medicine) Physician providers in California
There are 532 geriatric medicine (internal medicine) physician records in California.
All 532 in California → Every provider in San Gabriel → Geriatric Medicine (Internal Medicine) Physician nationwide →
The 8 geriatric medicine (internal medicine) physician records with the nearest ZIP codes
- Franck Juste, M.D.Temple City, CA 917801174605349
- Dan Tran, M.D.Rosemead, CA 917701487709747
- Sudhakar Kona, MDPomona, CA 917671619080215
- Hedy Loa, MDOntario, CA 917621093720666
- Oliver Tsai, M.D.West Covina, CA 917901306828272
- Ryan Uyan, MDMonterey Park, CA 917541275996050
- Victor Lee, M.D.Alhambra, CA 918031205903994
- Albert Bui, M.D.Hacienda Heights, CA 917451548536188
Common questions
What is Oscar L. Chien, M.D.'s NPI number?
Oscar L. Chien, M.D.'s National Provider Identifier (NPI) is 1679675904, issued on Sep 5, 2006. An NPI identifies a provider in billing; it is not a license.
Where is Oscar L. Chien, M.D. located?
The NPPES record lists a practice address at 1448 S. San Gabriel BL., San Gabriel, CA, 91776. Phone: (626) 569-2888. Providers update this record themselves, so call before visiting.
How can I verify Oscar L. Chien, M.D.'s license?
NPPES lists California license number A54999, as entered by the provider. Search the Medical Board of California at https://www.mbc.ca.gov/License-Verification/default.aspx. The NPPES record confirms identity only; the state search shows license status, expiration and public orders.
How much does Oscar L. Chien, M.D. prescribe under Medicare Part D?
In 2024, Oscar L. Chien, M.D. had 43,068 Medicare Part D claims for 1,086 beneficiaries; the average among geriatric medicine (internal medicine) physician prescribers was 4,246. Part D covers Medicare prescriptions only.
What is Oscar L. Chien, M.D.'s MIPS final score?
The 2023 MIPS final score is 13.2 of 100. The average among 454,083 clinicians with a measured score was 83.5.
Source: CMS National Plan and Provider Enumeration System (NPPES), file of Aug 9, 2026 (NPPES files on CMS.gov); NUCC Health Care Provider Taxonomy. Medicare files from data.cms.gov. An NPI identifies who bills; it is not a license.
Figures on PlainDoctor are read from the federal files each page names (CMS NPPES, Medicare Part D, MIPS, Open Payments; the HHS-OIG exclusion list only as counts) and from Census population estimates, with the file date shown beside them. See our editorial standards & corrections policy, the methodology behind these numbers, or report a data error. Data current as of Aug 9, 2026.