NPI registry status
Active
2026 NPPES data Urology Physician NPI 1639121395 M.D.
Verify on CMS → Gary Chien, M.D.
Urology 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 13,350 in Urology 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
626
Medicare Part D claims · 200 beneficiaries · Urology Physician avg: 1K
Compiled from official public sources by the PlainDoctor editorial team.
What the federal data shows
Gary Chien, M.D. filed 626 Medicare Part D claims in 2023 as a Urology Physician in Los Angeles, California.
- 626
- Part D claims, 2023
- Likely
- board-certified (heuristic)
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.
Gary Chien, M.D.'s Medicare Part D volume vs every U.S. prescriber
Total Medicare Part D claims, 2023, across all CMS prescribers nationally
626 Top 31% higher than 69% 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 certification likely (heuristic, not verified)
Gary Chien, 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 Gary Chien, M.D.?
Quality data not reportedPrimary specialty
Urology Physician
Medicare Part D claims
626 51% vs specialty avg
Specialty distribution in California
How Urology 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 Urology 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).
Gary Chien, M.D. appears in the CMS NPPES registry as a Urology Physician provider holding M.D. credentials at 4900 W SUNSET BLVD, Los Angeles, CA, 90027, with a listed phone of (800) 954-8000. NPI 1639121395 was issued on 05/17/2006.
Medicare Part D records for calendar year 2023 show 626 prescription claims written by this provider, covering 200 Medicare beneficiaries and totaling roughly $26K in drug spend.
Urology Physician is a mid-sized specialty nationwide, with 13,350 enrolled providers across 54 states and an average of 1,280 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 | 1639121395 |
|---|---|
| Specialty | Urology Physician |
| Credentials | M.D. |
| Gender | Male |
| NPI Issued | 05/17/2006 |
Hospital and facility affiliations
Facilities where Gary Chien, 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.
Southern California Permanente Medical Group
Los Angeles, 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 Gary Chien, M.D.. To verify Gary Chien, 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.
Medicare Part D Prescribing Data
CMS Medicare Part D prescriber-level data for calendar year 2023.
626
Total Claims
$26K
Total Drug Cost
200
Medicare Beneficiaries
Prescribing Breakdown
- 30-Day Fills
- 1,868
- Total Day Supply
- 54,945
- Generic Drug Cost
- $16K
- Antibiotic Claims
- 53
Patient Demographics
- Average Patient Age
- 76.3 years
- Avg HCC Risk Score
- 1.38
- Gender Split
- 11% female / 89% male
Top Prescribed Drugs (Medicare Part D)
Top drugs by claim count for calendar year 2023. Based on Medicare Part D data only.
What Gary Chien, M.D. prescribes most
Top Medicare Part D drugs by claim count, 2023
- Finasteride
Finasteride
245 claims
- Terazosin Hcl
Terazosin Hcl
128 claims
- Tamsulosin Hcl
Tamsulosin Hcl
110 claims
- Cephalexin 14
Cephalexin
14 claims
- Potassium Citrate Er 14
Potassium Citrate Er
14 claims
- Nitrofurantoin Mon… 12
Nitrofurantoin Mono-Macro
12 claims
- Sulfamethoxazole-T… 11
Sulfamethoxazole-Trimethoprim
11 claims
| Drug | Claims |
|---|---|
| Finasteride | 245 |
| Terazosin Hcl | 128 |
| Tamsulosin Hcl | 110 |
| Cephalexin | 14 |
| Potassium Citrate Er Potassium Citrate | 14 |
| Nitrofurantoin Mono-Macro Nitrofurantoin Monohyd/M-Cryst | 12 |
| Sulfamethoxazole-Trimethoprim Sulfamethoxazole/Trimethoprim | 11 |
* Counts below 11 are suppressed by CMS for patient privacy. Generic names shown where available from CMS Part D data.
Urology Physician Overview
How Gary Chien, M.D. fits within the Urology Physician landscape nationally.
13,350
Urology Physician Providers in US
54
States with Urology Physician
1,280
Avg Claims per Provider
Gary Chien, M.D.'s 626 claims are below the specialty average of 1,280.
Nearby Urology Physician Providers in California
Other clinicians with the same primary specialty enrolled in California, drawn from the same CMS NPPES roster as Chien.
Dr. David Aaronson
MD
Oakland, CA
Dr. Jason Abber
MD
Panorama City, CA
Dr. Marc Abboud
MD
Los Alamitos, CA
George Abdelsayed
Anaheim, CA
Garen Abedi
Downey, CA
Compare Urology 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 Urology 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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Frequently Asked Questions
What is Gary Chien, M.D.'s specialty? ▼
Gary Chien, M.D. specializes in Urology Physician and practices in Los Angeles, California. Credentials: M.D..
How much does Gary Chien, M.D. prescribe under Medicare Part D? ▼
In 2023, Gary Chien, M.D. wrote 626 Medicare Part D claims totaling $26K in drug costs for 200 beneficiaries.
Where is Gary Chien, M.D. located? ▼
Gary Chien, M.D. is located at 4900 W SUNSET BLVD, Los Angeles, CA, 90027. Phone: (800) 954-8000.
What is Gary Chien, M.D.'s NPI number? ▼
Gary Chien, M.D.'s National Provider Identifier (NPI) is 1639121395, issued on 05/17/2006.
How many Urology Physician providers are there in the US? ▼
There are 13,350 Urology Physician providers across 54 states in the US. The average Urology Physician provider writes 1,280 Medicare Part D claims per year.
What drugs does Gary Chien, M.D. prescribe most often? ▼
Based on 2023 Medicare Part D data, Gary Chien, M.D.'s most frequently prescribed drugs include Finasteride, Terazosin Hcl, Tamsulosin Hcl. This reflects Medicare Part D prescriptions only and does not include commercial insurance or other payer types.
Does Gary Chien, M.D. accept Medicare? ▼
Gary Chien, M.D. appears in CMS Medicare data with 626 Part D claims and 200 Medicare beneficiaries in 2023. Contact the provider's office directly to confirm current Medicare enrollment and accepted plans.
How can I verify Gary Chien, M.D.'s credentials? ▼
Gary Chien, M.D.'s NPI is 1639121395 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.