NPI registry status
Active
2026 NPPES data Emergency Medicine Physician NPI 1235175233 MD,MPH
Verify on CMS → Walter Maier, MD,MPH
Emergency Medicine Physician in Lake Arrowhead, 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 64,463 in Emergency 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
10K
Medicare Part D claims · 472 beneficiaries · Emergency Medicine Physician avg: 352
Generic prescribing
87%
generic claims · 12% brand-name · higher generic rates reduce patient out-of-pocket costs
MIPS score
12.6/100
▼ 71 pts below national avg 83.5 · Penalty band
Industry payments
$69.87
4 payments · CMS Open Payments (Sunshine Act)
Source: CMS Medicare Part D Prescriber Public Use File, 2023
What the federal data shows
Walter Maier, MD,MPH reported a CMS MIPS final score of 12.6/100 - below the 83.5 national average - and filed 9,708 Medicare Part D claims in 2023.
- 12.6/100
- MIPS score · -71 vs avg
- 10K
- Part D claims, 2023
- 87%
- 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.
Walter Maier, MD,MPH's MIPS score vs every measured U.S. clinician
CMS Merit-based Incentive Payment System (MIPS) final score, 2023, the federal quality measure. Clinicians whose score CMS assigned without scoring any category are excluded.
13 ≥ 2nd percentile 2% of 454,083 measured providers are in lower value bands
Each bar is a band; taller bars hold more measured providers. 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.
The percentile is a conservative whole-score-point band: it counts only measured clinicians in lower score bands. A CMS MIPS metric is not a recommendation or a clinical-quality rating by PlainDoctor. See methodology § corpus placement.
Source CMS Merit-based Incentive Payment System (MIPS) · 2023
Where Walter Maier, MD,MPH sits
This provider among emergency medicine physician peers
Across the 14,017 emergency medicine physician providers who report both Medicare Part D prescribing and a MIPS quality score, Walter Maier, MD,MPH writes more Part D claims than 100% of them and scores higher on MIPS quality than 1% - placing this provider in the high-volume, lower-quality quadrant. Volume reflects patient-panel size and specialty, not quality; the two axes are independent.
Part D claim volume vs MIPS quality, by specialty percentile
Each dot is one emergency medicine physician peer from a representative sample of 60; the gold marker is Walter Maier, MD,MPH. Source: CMS Medicare Part D Prescriber data and the CMS Merit-based Incentive Payment System, 2023.
✓
Board certification likely (heuristic, not verified)
Walter Maier, MD,MPH practices in an ABMS-board-eligible specialty and shows active CMS Medicare participation + MIPS quality reporting - 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 Walter Maier, MD,MPH?
Below national averagePrimary specialty
Emergency Medicine Physician
Medicare Part D claims
9,708 28× vs specialty avg
MIPS final score
12.6/100 70.9 pts vs avg
Specialty distribution in California
How Emergency Medicine Physician compares to other specialties among California providers
Medicare quality performance, MIPS
Walter Maier, MD,MPH's 2023 MIPS final score plotted against the Emergency Medicine Physician national average
- MIPS Final Score
- 12.6/100
- vs 83.5 national avg · 2023 performance year
MIPS final score (Emergency Medicine Physician) - 12.6/100 vs national avg 83.5
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).
Walter Maier, MD,MPH appears in the CMS NPPES registry as an Emergency Medicine Physician provider holding MD,MPH credentials at 29099 HOSPITAL ROAD, Lake Arrowhead, CA, 92352, with a listed phone of (909) 337-3661. NPI 1235175233 was issued on 06/20/2006.
Medicare Part D records for calendar year 2023 show 9,708 prescription claims written by this provider, covering 472 Medicare beneficiaries and totaling roughly $785K in drug spend, split 12% brand-name and 87% generic by claim count, with an opioid prescribing rate of 4.1%. On the CMS Merit-based Incentive Payment System, this provider earned a Final Score of 12.6/100 for the 2023 performance year (Quality 0, Cost 42.1), compared with the 83.5 average among clinicians with a measured score.
Emergency Medicine Physician is a high-volume specialty nationwide, with 64,463 enrolled providers across 56 states and an average of 352 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 | 1235175233 |
|---|---|
| Specialty | Emergency Medicine Physician |
| Credentials | MD,MPH |
| Gender | Male |
| NPI Issued | 06/20/2006 |
CMS Quality Score (MIPS)
Merit-based Incentive Payment System (MIPS) scores from CMS, 2023 performance year.
12.6418
Final Score
Measured-score avg: 83.5
0
Quality
42.1394
Cost
Reporting: Individual
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 Walter Maier, MD,MPH. Source: openpaymentsdata.cms.gov.
Total received
$70
Largest payer
AstraZeneca Pharmaceuticals LP
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 Walter Maier, MD,MPH. To verify Walter Maier, MD,MPH'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
Walter Maier, MD,MPH - brand share 12.0%
Emergency Medicine Physician average
12% brand-name claims vs 87% generic, on 9,708 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.
9,708
Total Claims
$785K
Total Drug Cost
472
Medicare Beneficiaries
Prescribing Breakdown
- 30-Day Fills
- 16,687
- Total Day Supply
- 482,739
- Brand vs Generic
- 12% brand / 87% generic
- Brand Drug Cost
- $594K
- Generic Drug Cost
- $187K
- Opioid Claims
- 402 (4.1% rate)
- Antibiotic Claims
- 270
Patient Demographics
- Average Patient Age
- 73.1 years
- Avg HCC Risk Score
- 1.16
- Gender Split
- 54% female / 46% male
- Age Distribution
- <65: 35, 65-74: 251, 75-84: 144, 85+: 42
Top Prescribed Drugs (Medicare Part D)
Top drugs by claim count for calendar year 2023. Based on Medicare Part D data only.
What Walter Maier, MD,MPH prescribes most
Top Medicare Part D drugs by claim count, 2023
- Levothyroxine Sodium
Levothyroxine Sodium
472 claims
- Losartan Potassium
Losartan Potassium
358 claims
- Atorvastatin Calcium
Atorvastatin Calcium
343 claims
- Amlodipine Besylate
Amlodipine Besylate
338 claims
- Gabapentin
Gabapentin
303 claims
- Hydrocodone-Acetam…
Hydrocodone-Acetaminophen
278 claims
- Potassium Chloride
Potassium Chloride
226 claims
- Furosemide
Furosemide
193 claims
| Drug | Claims |
|---|---|
| Levothyroxine Sodium | 472 |
| Losartan Potassium | 358 |
| Atorvastatin Calcium | 343 |
| Amlodipine Besylate | 338 |
| Gabapentin | 303 |
| Hydrocodone-Acetaminophen Hydrocodone/Acetaminophen | 278 |
| Potassium Chloride | 226 |
| Furosemide | 193 |
| Sertraline Hcl | 167 |
| Simvastatin | 161 |
* Counts below 11 are suppressed by CMS for patient privacy. Generic names shown where available from CMS Part D data.
Emergency Medicine Physician Overview
How Walter Maier, MD,MPH fits within the Emergency Medicine Physician landscape nationally.
64,463
Emergency Medicine Physician Providers in US
56
States with Emergency Medicine Physician
352
Avg Claims per Provider
Walter Maier, MD,MPH's 9,708 claims are above the specialty average of 352.
Nearby Emergency Medicine Physician Providers in California
Other clinicians with the same primary specialty enrolled in California, drawn from the same CMS NPPES roster as Maier.
Dr. Cooper Aakhus
MD
Stanford, CA
Dr. Pyra Aarden
MD
Martinez, CA
Dr. Neal Aaron
D.O.
Encinitas, CA
Eric Aaserude
Walnut Creek, CA
Dr. Nader Abas
MD
Barstow, CA
Compare Emergency 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 Emergency 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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Frequently Asked Questions
What is Walter Maier, MD,MPH's specialty? ▼
Walter Maier, MD,MPH specializes in Emergency Medicine Physician and practices in Lake Arrowhead, California. Credentials: MD,MPH.
How much does Walter Maier, MD,MPH prescribe under Medicare Part D? ▼
In 2023, Walter Maier, MD,MPH wrote 9,708 Medicare Part D claims totaling $785K in drug costs for 472 beneficiaries.
What is Walter Maier, MD,MPH's Medicare quality score? ▼
Walter Maier, MD,MPH has a CMS MIPS Final Score of 12.6/100 (Quality: 0, Cost: 42.1). The average MIPS Final Score across the 454,083 clinicians with at least one published category score is 83.5; clinicians whose score CMS assigned without scoring any category are excluded from that average. Source: CMS Merit-based Incentive Payment System (MIPS) 2023.
Where is Walter Maier, MD,MPH located? ▼
Walter Maier, MD,MPH is located at 29099 HOSPITAL ROAD, Lake Arrowhead, CA, 92352. Phone: (909) 337-3661.
What is Walter Maier, MD,MPH's NPI number? ▼
Walter Maier, MD,MPH's National Provider Identifier (NPI) is 1235175233, issued on 06/20/2006.
Does Walter Maier, MD,MPH prescribe more brand-name or generic drugs? ▼
Walter Maier, MD,MPH's prescribing is 12% brand-name and 87% generic drugs by claim count, with $594K in brand drug costs.
Does Walter Maier, MD,MPH prescribe opioids? ▼
Yes, Walter Maier, MD,MPH had 402 opioid claims in 2023 with an opioid prescribing rate of 4.1%.
How many Emergency Medicine Physician providers are there in the US? ▼
There are 64,463 Emergency Medicine Physician providers across 56 states in the US. The average Emergency Medicine Physician provider writes 352 Medicare Part D claims per year.
What drugs does Walter Maier, MD,MPH prescribe most often? ▼
Based on 2023 Medicare Part D data, Walter Maier, MD,MPH's most frequently prescribed drugs include Levothyroxine Sodium, Losartan Potassium, Atorvastatin Calcium. This reflects Medicare Part D prescriptions only and does not include commercial insurance or other payer types.
Does Walter Maier, MD,MPH accept Medicare? ▼
Walter Maier, MD,MPH appears in CMS Medicare data with 9,708 Part D claims and 472 Medicare beneficiaries in 2023. Contact the provider's office directly to confirm current Medicare enrollment and accepted plans.
How can I verify Walter Maier, MD,MPH's credentials? ▼
Walter Maier, MD,MPH's NPI is 1235175233 with credentials MD,MPH. 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.
- Quality Performance
- CMS Merit-based Incentive Payment System (MIPS) - 2023 performance year.
- 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
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.