2026 NPPES data Adolescent Medicine (Internal Medicine) Physician NPI 1689665093 MD
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ROBERT GRASS, MD

Adolescent Medicine (Internal Medicine) Physician in FOND DU LAC, Wisconsin. CMS National Plan and Provider Enumeration System profile including specialty classification, practice address, and Medicare prescribing data when reported.

Federal data — no proprietary rating. PlainDoctor publishes the actual CMS NPPES and Medicare records — NPI registration, specialty, practice location, and prescribing data — without a composite score or editorial opinion on top. Every field traces to a federal source.
Prescribing volume
6K
Medicare Part D claims · 358 beneficiaries · Adolescent Medicine (Internal Medicine) Physician avg: 3K
Generic prescribing
90%
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)

What the federal data shows

ROBERT GRASS, MD filed 5,863 Medicare Part D claims in 2023 as a Adolescent Medicine (Internal Medicine) Physician in FOND DU LAC, Wisconsin, prescribing 90% generic.

6K
Part D claims, 2023
90%
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.

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 Top 5% higher than 95% of 1,370,886 prescribers

0–200: 670,926 prescribers (49%). Below this entry. 200–400: 182,923 prescribers (13%). Below this entry. 400–600: 90,619 prescribers (7%). Below this entry. 600–800: 56,224 prescribers (4%). Below this entry. 800–1,000: 40,919 prescribers (3%). Below this entry. 1,000–1,200: 31,827 prescribers (2%). Below this entry. 1,200–1,400: 26,224 prescribers (2%). Below this entry. 1,400–1,600: 21,710 prescribers (2%). Below this entry. 1,600–1,800: 19,072 prescribers (1%). Below this entry. 1,800–2,000: 16,451 prescribers (1%). Below this entry. 2,000–2,200: 213,991 prescribers (16%). This entry sits in this band. This provider 0 2K+ every Part D prescriber (claims/yr), bucketed by value

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)

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 reported

NPI registry status

Active

Issued 11/03/2005

NPI 1689665093

Primary specialty

Adolescent Medicine (Internal Medicine) Physician

Rare

377 US NPIs in this specialty

Medicare Part D claims

5,863 81% vs specialty avg

2023 prescription claims

Specialty avg: 3,242

Specialty distribution in Wisconsin

How Adolescent Medicine (Internal Medicine) Physician compares to other specialties among Wisconsin providers

Wisconsin providers

Adolescent Medicine (Internal Medicine) Physician share within Wisconsin

1. Adolescent Medicine (Internal Medicine) Physician42%2. Internal medicine21%3. Family medicine17%4. Surgical12%5. Pediatric8%
Adolescent Medicine (Internal Medicine) Physician share within Wisconsin

Specialty board-certification context

Estimated specialty board-certified rate — Adolescent Medicine (Internal Medicine) Physician (ABMS / AOA reference)

Quality data not reported
Est. board-certified rate
78%
Adolescent Medicine (Internal Medicine) Physician ABMS/AOA estimate

Est. board-certified rate (Adolescent Medicine (Internal Medicine) Physician) — ABMS / AOA estimate

0%100%78%
Est. board-certified rate (Adolescent Medicine (Internal Medicine) Physician) — ABMS / AOA estimate

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).

ROBERT GRASS, MD appears in the CMS NPPES registry as a Adolescent Medicine (Internal Medicine) Physician provider holding MD credentials at 420 E DIVISION ST, FOND DU LAC, WI, 54935, with a listed phone of (920) 926-8615. NPI 1689665093 was issued on 11/03/2005. Because NPPES data is self-reported by the provider and refreshed monthly, the address, phone, and specialty reflect what GRASS most recently submitted to CMS rather than a vetted directory listing, which is why patients should always confirm the practice is still at this location before scheduling.

Medicare Part D records for calendar year 2023 show 5,863 prescription claims written by this provider, covering 358 Medicare beneficiaries and totaling roughly $473K in drug spend, split 10% brand-name and 90% generic by claim count, with an opioid prescribing rate of 1.8%. These figures capture only Medicare Part D — commercial insurance, Medicaid, and cash-pay prescriptions are not included, and any drug-beneficiary cell under 11 is suppressed by CMS for patient privacy.

Adolescent Medicine (Internal Medicine) Physician is a narrow specialty nationwide, with 377 enrolled providers across 46 states and an average of 3,242 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

420 E DIVISION ST
FOND DU LAC, WI 54935

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%
Specialty average (est.)

10% brand-name claims vs 90% 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 / 90% 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

claims
Source CMS Medicare Part D Prescriber Public Use File As of 2023
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.

Adolescent Medicine (Internal Medicine) Physician Overview

How ROBERT GRASS, MD fits within the Adolescent Medicine (Internal Medicine) Physician landscape nationally.

377
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.

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.

Compare Adolescent Medicine (Internal Medicine) Physician nationally: see state-by-state distribution →

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 90% 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 377 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

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