NPI registry status
Active
2026 NPPES data Adolescent Medicine (Internal Medicine) Physician NPI 1689665093 MD
Verify on CMS → Robert Grass, MD
Adolescent Medicine (Internal Medicine) Physician in Fond Du Lac, Wisconsin.
This profile is drawn from the federal National Provider Identifier Registry (CMS NPPES), which lists more than 7 million U.S. healthcare providers - including 375 in Adolescent Medicine (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 · 358 beneficiaries · Adolescent Medicine (Internal Medicine) Physician avg: 3K
Generic prescribing
89%
generic claims · 10% brand-name · higher generic rates reduce patient out-of-pocket costs
Industry payments
$16.65
1 payments · CMS Open Payments (Sunshine Act)
Source: CMS Medicare Part D Prescriber Public Use File, 2023
What the federal data shows
Robert Grass, MD filed 5,863 Medicare Part D claims in 2023 as an Adolescent Medicine (Internal Medicine) Physician in Fond Du Lac, Wisconsin, prescribing 89% generic.
- 6K
- Part D claims, 2023
- 89%
- generic prescribing
- Likely
- board-certified (heuristic)
- ≥95th
- pct by Part D claim volume (lower-bound band)
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.
CMS NPPES provider registry desk
NPI 1689665093 · Adolescent Medicine (Internal Medicine) Physician
NPI-10 · ENUM-LEGACY · TAX-TRACE · RX-MID · BOOK-THIN · PHOTO-ENUM
- NPI-10 1689665093
- ENUM-LEGACY 2005
- TAX-TRACE 375
- RX-MID 5,863
- BOOK-THIN 5 in Wisconsin
- PHOTO-ENUM Touquir Zahra · 2005
Robert Grass, MD's Medicare Part D volume vs every U.S. prescriber
Total Medicare Part D claims, 2023, across all CMS prescribers nationally
5,863 ≥ 95th percentile 95% of 1,370,886 prescribers are in lower value bands
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.
The percentile is a conservative 100-claim band: it counts only prescribers in lower claim-volume bands. Medicare Part D claim volume is activity context, not a quality measure or recommendation. See methodology § corpus placement.
Source CMS Medicare Part D Prescriber Public Use File · 2023
✓
Board certification likely (heuristic, not verified)
Robert Grass, MD 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 Robert Grass, MD?
Quality data not reportedPrimary specialty
Adolescent Medicine (Internal Medicine) Physician
Medicare Part D claims
5,863 81% vs specialty avg
Specialty distribution in Wisconsin
How Adolescent Medicine (Internal Medicine) Physician compares to other specialties among Wisconsin 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 Adolescent Medicine (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).
Practice Address
Provider Details
| NPI | 1689665093 |
|---|---|
| Specialty | Adolescent Medicine (Internal Medicine) Physician |
| Credentials | MD |
| Gender | Male |
| NPI Issued | 11/03/2005 |
Hospital and facility affiliations
Facilities where Robert Grass, MD 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.
Agnesian Healthcare Inc
Fond Du Lac, WI
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 Robert Grass, MD. Source: openpaymentsdata.cms.gov.
Total received
$17
Largest payer
E.R. Squibb & Sons, L.L.C.
Most common payment type
Education
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.
Brand vs generic prescribing mix · Typical
Robert Grass, MD - brand share 10.0%
Adolescent Medicine (Internal Medicine) Physician average
10% brand-name claims vs 89% generic, on 5,863 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.
5,863
Total Claims
$473K
Total Drug Cost
358
Medicare Beneficiaries
Prescribing Breakdown
- 30-Day Fills
- 12,772
- Total Day Supply
- 372,034
- Brand vs Generic
- 10% brand / 89% generic
- Brand Drug Cost
- $343K
- Generic Drug Cost
- $126K
- Opioid Claims
- 103 (1.8% rate)
- Antibiotic Claims
- 101
Patient Demographics
- Average Patient Age
- 73.3 years
- Avg HCC Risk Score
- 1.20
- Gender Split
- 37% female / 63% male
- Age Distribution
- <65: 34, 65-74: 172, 75-84: 116, 85+: 36
Top Prescribed Drugs (Medicare Part D)
Top drugs by claim count for calendar year 2023. Based on Medicare Part D data only.
What Robert Grass, MD prescribes most
Top Medicare Part D drugs by claim count, 2023
- Atorvastatin Calcium
Atorvastatin Calcium
303 claims
- Lisinopril
Lisinopril
198 claims
- Hydrochlorothiazide
Hydrochlorothiazide
196 claims
- Amlodipine Besylate
Amlodipine Besylate
188 claims
- Omeprazole
Omeprazole
169 claims
- Simvastatin
Simvastatin
168 claims
- Levothyroxine Sodium
Levothyroxine Sodium
167 claims
- Losartan Potassium
Losartan Potassium
151 claims
| Drug | Claims |
|---|---|
| Atorvastatin Calcium | 303 |
| Lisinopril | 198 |
| Hydrochlorothiazide | 196 |
| Amlodipine Besylate | 188 |
| Omeprazole | 169 |
| Simvastatin | 168 |
| Levothyroxine Sodium | 167 |
| Losartan Potassium | 151 |
| Pantoprazole Sodium | 125 |
| Sertraline Hcl | 116 |
* Counts below 11 are suppressed by CMS for patient privacy. Generic names shown where available from CMS Part D data.
More Adolescent Medicine (Internal Medicine) Physician in WI →
All providers in Wisconsin →
Compare specialties →
Adolescent Medicine (Internal Medicine) Physician Overview
How Robert Grass, MD fits within the Adolescent Medicine (Internal Medicine) Physician landscape nationally.
375
Adolescent Medicine (Internal Medicine) Physician Providers in US
46
States with Adolescent Medicine (Internal Medicine) Physician
3,242
Avg Claims per Provider
Robert Grass, MD's 5,863 claims are above the specialty average of 3,242.
Nationwide Adolescent Medicine (Internal Medicine) Physician peers with similar MIPS or enrollment year
Two federal-record peer sets for Grass, both outside Wisconsin so the neighborhoods are not geographic containment.
Same NPPES enumeration year (2005)
Same-specialty clinicians who entered the NPI registry in the same calendar year, outside this state.
Nearby Adolescent Medicine (Internal Medicine) Physician Providers in Wisconsin
Other clinicians with the same primary specialty enrolled in Wisconsin, drawn from the same CMS NPPES roster as Grass.
One of 5 Adolescent Medicine (Internal Medicine) Physician providers enrolled in Wisconsin, 4 are shown here.
Frequently Asked Questions
What is Robert Grass, MD's specialty? ▼
Robert Grass, MD specializes in Adolescent Medicine (Internal Medicine) Physician and practices in Fond Du Lac, Wisconsin. Credentials: MD.
How much does Robert Grass, MD prescribe under Medicare Part D? ▼
In 2023, Robert Grass, MD wrote 5,863 Medicare Part D claims totaling $473K in drug costs for 358 beneficiaries.
Where is Robert Grass, MD located? ▼
Robert Grass, MD is located at 420 E DIVISION ST, Fond Du Lac, WI, 54935. Phone: (920) 926-8615.
What is Robert Grass, MD's NPI number? ▼
Robert Grass, MD's National Provider Identifier (NPI) is 1689665093, issued on 11/03/2005.
Does Robert Grass, MD prescribe more brand-name or generic drugs? ▼
Robert Grass, MD's prescribing is 10% brand-name and 89% generic drugs by claim count, with $343K in brand drug costs.
Does Robert Grass, MD prescribe opioids? ▼
Yes, Robert Grass, MD had 103 opioid claims in 2023 with an opioid prescribing rate of 1.8%.
How many Adolescent Medicine (Internal Medicine) Physician providers are there in the US? ▼
There are 375 Adolescent Medicine (Internal Medicine) Physician providers across 46 states in the US. The average Adolescent Medicine (Internal Medicine) Physician provider writes 3,242 Medicare Part D claims per year.
What drugs does Robert Grass, MD prescribe most often? ▼
Based on 2023 Medicare Part D data, Robert Grass, MD's most frequently prescribed drugs include Atorvastatin Calcium, Lisinopril, Hydrochlorothiazide. This reflects Medicare Part D prescriptions only and does not include commercial insurance or other payer types.
Does Robert Grass, MD accept Medicare? ▼
Robert Grass, MD appears in CMS Medicare data with 5,863 Part D claims and 358 Medicare beneficiaries in 2023. Contact the provider's office directly to confirm current Medicare enrollment and accepted plans.
How can I verify Robert Grass, MD's credentials? ▼
Robert Grass, MD's NPI is 1689665093 with credentials MD. 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
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.