NPI registry status
Active
2026 NPPES data Medical Oncology Physician NPI 1134540859 M.D.
Verify on CMS → Siao-Yi Wang, M.D.
Medical Oncology Physician in Sacramento, 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 3,815 in Medical Oncology 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
277
Medicare Part D claims · 65 beneficiaries · Medical Oncology Physician avg: 689
Generic prescribing
88%
generic claims · 12% brand-name · higher generic rates reduce patient out-of-pocket costs
Industry payments
$160.99
1 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
Siao-Yi Wang, M.D. filed 277 Medicare Part D claims in 2023 as a Medical Oncology Physician in Sacramento, California, prescribing 88% generic.
- 277
- Part D claims, 2023
- 88%
- generic prescribing
- 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.
Siao-Yi Wang, M.D.'s Medicare Part D volume vs every U.S. prescriber
Total Medicare Part D claims, 2023, across all CMS prescribers nationally
277 49th percentile higher than 49% 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)
Siao-Yi Wang, 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 Siao-Yi Wang, M.D.?
Quality data not reportedPrimary specialty
Medical Oncology Physician
Medicare Part D claims
277 60% vs specialty avg
Specialty distribution in California
How Medical Oncology 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 Medical Oncology 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).
Siao-Yi Wang, M.D. appears in the CMS NPPES registry as a Medical Oncology Physician provider holding M.D. credentials at 2279 45TH ST, Sacramento, CA, 95817, with a listed phone of (916) 734-5959. NPI 1134540859 was issued on 12/23/2013.
Medicare Part D records for calendar year 2023 show 277 prescription claims written by this provider, covering 65 Medicare beneficiaries and totaling roughly $327K in drug spend, split 12% brand-name and 88% generic by claim count, with an opioid prescribing rate of 4.7%.
Medical Oncology Physician is a narrow specialty nationwide, with 3,815 enrolled providers across 53 states and an average of 689 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 | 1134540859 |
|---|---|
| Specialty | Medical Oncology Physician |
| Credentials | M.D. |
| Gender | Male |
| NPI Issued | 12/23/2013 |
Hospital and facility affiliations
Facilities where Siao-Yi Wang, 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.
Regents OF The Univ OF CA
Sacramento, 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).
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 Siao-Yi Wang, M.D.. Source: openpaymentsdata.cms.gov.
Total received
$161
Largest payer
Tempus AI, 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 Siao-Yi Wang, M.D.. To verify Siao-Yi Wang, 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
Siao-Yi Wang, M.D. - brand share 12.0%
Medical Oncology Physician average
12% brand-name claims vs 88% generic, on 277 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.
277
Total Claims
$327K
Total Drug Cost
65
Medicare Beneficiaries
Prescribing Breakdown
- 30-Day Fills
- 315
- Total Day Supply
- 5,971
- Brand vs Generic
- 12% brand / 88% generic
- Brand Drug Cost
- $323K
- Generic Drug Cost
- $4K
- Opioid Claims
- 13 (4.7% rate)
Patient Demographics
- Average Patient Age
- 74.5 years
- Avg HCC Risk Score
- 2.69
- Gender Split
- 43% female / 57% male
Top Prescribed Drugs (Medicare Part D)
Top drugs by claim count for calendar year 2023. Based on Medicare Part D data only.
What Siao-Yi Wang, M.D. prescribes most
Top Medicare Part D drugs by claim count, 2023
- Dexamethasone
Dexamethasone
42 claims
- Prochlorperazine M…
Prochlorperazine Maleate
31 claims
- Levothyroxine Sodium
Levothyroxine Sodium
29 claims
- Ondansetron Hcl
Ondansetron Hcl
25 claims
- Olanzapine
Olanzapine
19 claims
- Tagrisso 13
Tagrisso
13 claims
- Furosemide 12
Furosemide
12 claims
- Prednisone 11
Prednisone
11 claims
| Drug | Claims |
|---|---|
| Dexamethasone | 42 |
| Prochlorperazine Maleate | 31 |
| Levothyroxine Sodium | 29 |
| Ondansetron Hcl | 25 |
| Olanzapine | 19 |
| Tagrisso Osimertinib Mesylate | 13 |
| Furosemide | 12 |
| Prednisone | 11 |
* Counts below 11 are suppressed by CMS for patient privacy. Generic names shown where available from CMS Part D data.
Medical Oncology Physician Overview
How Siao-Yi Wang, M.D. fits within the Medical Oncology Physician landscape nationally.
3,815
Medical Oncology Physician Providers in US
53
States with Medical Oncology Physician
689
Avg Claims per Provider
Siao-Yi Wang, M.D.'s 277 claims are below the specialty average of 689.
Nearby Medical Oncology Physician Providers in California
Other clinicians with the same primary specialty enrolled in California, drawn from the same CMS NPPES roster as Wang.
Dr. Ranjana Advani
MD
Stanford, CA
Dr. Kambiz Afrasiabi
M.D.
Anaheim, CA
Dr. Mark Agulnik
MD
Los Angeles, CA
Dr. Weiyun Ai
MD
San Francisco, CA
Dr. Shafqat Akhtar
MD
Red Bluff, CA
Compare Medical Oncology 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 Medical Oncology 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 Siao-Yi Wang, M.D.'s specialty? ▼
Siao-Yi Wang, M.D. specializes in Medical Oncology Physician and practices in Sacramento, California. Credentials: M.D..
How much does Siao-Yi Wang, M.D. prescribe under Medicare Part D? ▼
In 2023, Siao-Yi Wang, M.D. wrote 277 Medicare Part D claims totaling $327K in drug costs for 65 beneficiaries.
Where is Siao-Yi Wang, M.D. located? ▼
Siao-Yi Wang, M.D. is located at 2279 45TH ST, Sacramento, CA, 95817. Phone: (916) 734-5959.
What is Siao-Yi Wang, M.D.'s NPI number? ▼
Siao-Yi Wang, M.D.'s National Provider Identifier (NPI) is 1134540859, issued on 12/23/2013.
Does Siao-Yi Wang, M.D. prescribe more brand-name or generic drugs? ▼
Siao-Yi Wang, M.D.'s prescribing is 12% brand-name and 88% generic drugs by claim count, with $323K in brand drug costs.
Does Siao-Yi Wang, M.D. prescribe opioids? ▼
Yes, Siao-Yi Wang, M.D. had 13 opioid claims in 2023 with an opioid prescribing rate of 4.7%.
How many Medical Oncology Physician providers are there in the US? ▼
There are 3,815 Medical Oncology Physician providers across 53 states in the US. The average Medical Oncology Physician provider writes 689 Medicare Part D claims per year.
What drugs does Siao-Yi Wang, M.D. prescribe most often? ▼
Based on 2023 Medicare Part D data, Siao-Yi Wang, M.D.'s most frequently prescribed drugs include Dexamethasone, Prochlorperazine Maleate, Levothyroxine Sodium. This reflects Medicare Part D prescriptions only and does not include commercial insurance or other payer types.
Does Siao-Yi Wang, M.D. accept Medicare? ▼
Siao-Yi Wang, M.D. appears in CMS Medicare data with 277 Part D claims and 65 Medicare beneficiaries in 2023. Contact the provider's office directly to confirm current Medicare enrollment and accepted plans.
How can I verify Siao-Yi Wang, M.D.'s credentials? ▼
Siao-Yi Wang, M.D.'s NPI is 1134540859 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.
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 May 2026.