NPI registry status
Active
2026 NPPES data Rheumatology Physician NPI 1891703591 MD
Verify on CMS → Walter Marbach, MD
Rheumatology Physician in Crestwood, Illinois.
This profile is drawn from the federal National Provider Identifier Registry (CMS NPPES), which lists more than 7 million U.S. healthcare providers - including 6,181 in Rheumatology 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
2K
Medicare Part D claims · 126 beneficiaries · Rheumatology Physician avg: 2K
Generic prescribing
94%
generic claims · 6% brand-name · higher generic rates reduce patient out-of-pocket costs
Industry payments
$952.53
35 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
Walter Marbach, MD filed 1,628 Medicare Part D claims in 2023 as a Rheumatology Physician in Crestwood, Illinois, prescribing 94% generic.
- 2K
- Part D claims, 2023
- 94%
- 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 Marbach, MD's Medicare Part D volume vs every U.S. prescriber
Total Medicare Part D claims, 2023, across all CMS prescribers nationally
1,628 Top 18% higher than 82% 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)
Walter Marbach, 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 Walter Marbach, MD?
Quality data not reportedPrimary specialty
Rheumatology Physician
Medicare Part D claims
1,628 21% vs specialty avg
Specialty distribution in Illinois
How Rheumatology Physician compares to other specialties among Illinois 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 Rheumatology 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).
Walter Marbach, MD appears in the CMS NPPES registry as a Rheumatology Physician provider holding MD credentials at 13755 CICERO AVE, Crestwood, IL, 60445, with a listed phone of (888) 220-6432. NPI 1891703591 was issued on 08/04/2006.
Medicare Part D records for calendar year 2023 show 1,628 prescription claims written by this provider, covering 126 Medicare beneficiaries and totaling roughly $620K in drug spend, split 6% brand-name and 94% generic by claim count, with an opioid prescribing rate of 13.6%.
Rheumatology Physician is a mid-sized specialty nationwide, with 6,181 enrolled providers across 52 states and an average of 2,054 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 | 1891703591 |
|---|---|
| Specialty | Rheumatology Physician |
| Credentials | MD |
| Gender | Male |
| NPI Issued | 08/04/2006 |
Hospital and facility affiliations
Facilities where Walter Marbach, 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.
Metro Infectious Disease Consultants LLC
Crestwood, IL
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 Walter Marbach, MD. Source: openpaymentsdata.cms.gov.
Total received
$953
Largest payer
Amgen 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 - Illinois IDFPR 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 ~42K Illinois medical licensees in 2023 - they are NOT specific to Walter Marbach, MD. To verify Walter Marbach, MD's current license status, search the IDFPR public license lookup directly, or check the Federation of State Medical Boards (FSMB) verification service.
106
Total board actions, Illinois 2023
Across 103 cases
2.52
Actions per 1,000 licensees
Illinois statewide rate
probation
Most common action type
38 cases
IDFPR 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 Illinois disciplinary trends page. Cross-checked against FSMB U.S. Medical Regulatory Trends.
Brand vs generic prescribing mix · Generic-heavy
Walter Marbach, MD - brand share 6.0%
Rheumatology Physician average
6% brand-name claims vs 94% generic, on 1,628 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.
1,628
Total Claims
$620K
Total Drug Cost
126
Medicare Beneficiaries
Prescribing Breakdown
- 30-Day Fills
- 2,695
- Total Day Supply
- 77,589
- Brand vs Generic
- 6% brand / 94% generic
- Brand Drug Cost
- $562K
- Generic Drug Cost
- $57K
- Opioid Claims
- 221 (13.6% rate)
- Antibiotic Claims
- 21
Patient Demographics
- Average Patient Age
- 70.6 years
- Avg HCC Risk Score
- 1.77
- Gender Split
- 74% female / 26% male
Top Prescribed Drugs (Medicare Part D)
Top drugs by claim count for calendar year 2023. Based on Medicare Part D data only.
What Walter Marbach, MD prescribes most
Top Medicare Part D drugs by claim count, 2023
- Methotrexate
Methotrexate
228 claims
- Prednisone
Prednisone
138 claims
- Hydroxychloroquine…
Hydroxychloroquine Sulfate
128 claims
- Hydrocodone-Acetam…
Hydrocodone-Acetaminophen
114 claims
- Alprazolam 60
Alprazolam
60 claims
- Azathioprine 54
Azathioprine
54 claims
- Tramadol Hcl 51
Tramadol Hcl
51 claims
- Meloxicam 50
Meloxicam
50 claims
| Drug | Claims |
|---|---|
| Methotrexate Methotrexate Sodium | 228 |
| Prednisone | 138 |
| Hydroxychloroquine Sulfate | 128 |
| Hydrocodone-Acetaminophen Hydrocodone/Acetaminophen | 114 |
| Alprazolam | 60 |
| Azathioprine | 54 |
| Tramadol Hcl | 51 |
| Meloxicam | 50 |
| Gabapentin | 45 |
| Leflunomide | 45 |
* Counts below 11 are suppressed by CMS for patient privacy. Generic names shown where available from CMS Part D data.
Rheumatology Physician Overview
How Walter Marbach, MD fits within the Rheumatology Physician landscape nationally.
6,181
Rheumatology Physician Providers in US
52
States with Rheumatology Physician
2,054
Avg Claims per Provider
Walter Marbach, MD's 1,628 claims are below the specialty average of 2,054.
Nearby Rheumatology Physician Providers in Illinois
Other clinicians with the same primary specialty enrolled in Illinois, drawn from the same CMS NPPES roster as Marbach.
Dr. Elaine Adams
MD
Maywood, IL
Dr. Emem Adolf-Ubokudom
M.D.
Chicago, IL
Dr. Shri Agrawal
M.D.
Chicago, IL
Dr. Umber Ahmad
DO
McHenry, IL
Saba Ahmed
Chicago, IL
Compare Rheumatology 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 Illinois medical board, federal registration is not a license check. Credential verification guide
- Weigh a second option: compare this provider with a nearby Rheumatology 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 Marbach, MD's specialty? ▼
Walter Marbach, MD specializes in Rheumatology Physician and practices in Crestwood, Illinois. Credentials: MD.
How much does Walter Marbach, MD prescribe under Medicare Part D? ▼
In 2023, Walter Marbach, MD wrote 1,628 Medicare Part D claims totaling $620K in drug costs for 126 beneficiaries.
Where is Walter Marbach, MD located? ▼
Walter Marbach, MD is located at 13755 CICERO AVE, Crestwood, IL, 60445. Phone: (888) 220-6432.
What is Walter Marbach, MD's NPI number? ▼
Walter Marbach, MD's National Provider Identifier (NPI) is 1891703591, issued on 08/04/2006.
Does Walter Marbach, MD prescribe more brand-name or generic drugs? ▼
Walter Marbach, MD's prescribing is 6% brand-name and 94% generic drugs by claim count, with $562K in brand drug costs.
Does Walter Marbach, MD prescribe opioids? ▼
Yes, Walter Marbach, MD had 221 opioid claims in 2023 with an opioid prescribing rate of 13.6%.
How many Rheumatology Physician providers are there in the US? ▼
There are 6,181 Rheumatology Physician providers across 52 states in the US. The average Rheumatology Physician provider writes 2,054 Medicare Part D claims per year.
What drugs does Walter Marbach, MD prescribe most often? ▼
Based on 2023 Medicare Part D data, Walter Marbach, MD's most frequently prescribed drugs include Methotrexate, Prednisone, Hydroxychloroquine Sulfate. This reflects Medicare Part D prescriptions only and does not include commercial insurance or other payer types.
Does Walter Marbach, MD accept Medicare? ▼
Walter Marbach, MD appears in CMS Medicare data with 1,628 Part D claims and 126 Medicare beneficiaries in 2023. Contact the provider's office directly to confirm current Medicare enrollment and accepted plans.
How can I verify Walter Marbach, MD's credentials? ▼
Walter Marbach, MD's NPI is 1891703591 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
Compiled from official public sources by the PlainDoctor editorial team.