NPI registry status
Active
2026 NPPES data Sleep Medicine (Internal Medicine) Physician NPI 1003298720 M.D.
Verify on CMS → Nathan Nowalk, M.D.
Sleep Medicine (Internal Medicine) Physician in Chicago, 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 859 in Sleep 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
69
Medicare Part D claims · Sleep Medicine (Internal Medicine) Physician avg: 1K
Generic prescribing
42%
generic claims · 58% brand-name · higher generic rates reduce patient out-of-pocket costs
Industry payments
$126.11
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
Nathan Nowalk, M.D. filed 69 Medicare Part D claims in 2023 as a Sleep Medicine (Internal Medicine) Physician in Chicago, Illinois, prescribing 42% generic.
- 69
- Part D claims, 2023
- 42%
- 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.
Nathan Nowalk, M.D.'s Medicare Part D volume vs every U.S. prescriber
Total Medicare Part D claims, 2023, across all CMS prescribers nationally
69 0th percentile higher than 0% 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)
Nathan Nowalk, M.D. practices in an ABMS-board-eligible specialty and shows active CMS Medicare participation + 2 hospital affiliations - 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 Nathan Nowalk, M.D.?
Quality data not reportedPrimary specialty
Sleep Medicine (Internal Medicine) Physician
Medicare Part D claims
69 95% vs specialty avg
Specialty distribution in Illinois
How Sleep Medicine (Internal Medicine) 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 Sleep 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).
Nathan Nowalk, M.D. appears in the CMS NPPES registry as a Sleep Medicine (Internal Medicine) Physician provider holding M.D. credentials at 5841 S MARYLAND AVE, Chicago, IL, 60637, with a listed phone of (888) 824-0200. NPI 1003298720 was issued on 06/18/2015.
Medicare Part D records for calendar year 2023 show 69 prescription claims written by this provider, covering N/A Medicare beneficiaries and totaling roughly $60K in drug spend, split 58% brand-name and 42% generic by claim count.
Sleep Medicine (Internal Medicine) Physician is a narrow specialty nationwide, with 859 enrolled providers across 52 states and an average of 1,310 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 | 1003298720 |
|---|---|
| Specialty | Sleep Medicine (Internal Medicine) Physician |
| Credentials | M.D. |
| Gender | Male |
| NPI Issued | 06/18/2015 |
Hospital and facility affiliations
Facilities where Nathan Nowalk, 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.
University OF Chicago
Chicago, IL
University OF Penn-Medical Group
Philadelphia, PA
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 Nathan Nowalk, M.D.. Source: openpaymentsdata.cms.gov.
Total received
$126
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 - 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 Nathan Nowalk, M.D.. To verify Nathan Nowalk, M.D.'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 · Brand-heavy
Nathan Nowalk, M.D. - brand share 58.0%
Sleep Medicine (Internal Medicine) Physician average
58% brand-name claims vs 42% generic, on 69 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.
69
Total Claims
$60K
Total Drug Cost
N/A
Medicare Beneficiaries
Prescribing Breakdown
- 30-Day Fills
- 84
- Total Day Supply
- 2,327
- Brand vs Generic
- 58% brand / 42% generic
- Brand Drug Cost
- $59K
- Generic Drug Cost
- $694
Patient Demographics
- Average Patient Age
- 71.4 years
- Avg HCC Risk Score
- 2.26
Top Prescribed Drugs (Medicare Part D)
Top drugs by claim count for calendar year 2023. Based on Medicare Part D data only.
What Nathan Nowalk, M.D. prescribes most
Top Medicare Part D drugs by claim count, 2023
- Anoro Ellipta
Anoro Ellipta
18 claims
- Albuterol Sulfate …
Albuterol Sulfate Hfa
15 claims
- Dupixent Syringe
Dupixent Syringe
12 claims
| Drug | Claims |
|---|---|
| Anoro Ellipta Umeclidinium Brm/Vilanterol Tr | 18 |
| Albuterol Sulfate Hfa Albuterol Sulfate | 15 |
| Dupixent Syringe Dupilumab | 12 |
* Counts below 11 are suppressed by CMS for patient privacy. Generic names shown where available from CMS Part D data.
More Sleep Medicine (Internal Medicine) Physician in IL →
All providers in Illinois →
Compare specialties →
Sleep Medicine (Internal Medicine) Physician Overview
How Nathan Nowalk, M.D. fits within the Sleep Medicine (Internal Medicine) Physician landscape nationally.
859
Sleep Medicine (Internal Medicine) Physician Providers in US
52
States with Sleep Medicine (Internal Medicine) Physician
1,310
Avg Claims per Provider
Nathan Nowalk, M.D.'s 69 claims are below the specialty average of 1,310.
Nearby Sleep Medicine (Internal Medicine) Physician Providers in Illinois
Other clinicians with the same primary specialty enrolled in Illinois, drawn from the same CMS NPPES roster as Nowalk.
Dr. Philip Abraham
M.D.
Springfield, IL
Dr. Mirza Abu Sayeem
MBBS
Chicago, IL
Dr. Noman Baig
MD
Chicago, IL
Dr. George Cromydas
M.D.
Arlington Heights, IL
Richard Czuma
Palos Heights, IL
Compare Sleep Medicine (Internal 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 Illinois medical board, federal registration is not a license check. Credential verification guide
- Weigh a second option: compare this provider with a nearby Sleep Medicine (Internal 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 Nathan Nowalk, M.D.'s specialty? ▼
Nathan Nowalk, M.D. specializes in Sleep Medicine (Internal Medicine) Physician and practices in Chicago, Illinois. Credentials: M.D..
How much does Nathan Nowalk, M.D. prescribe under Medicare Part D? ▼
In 2023, Nathan Nowalk, M.D. wrote 69 Medicare Part D claims totaling $60K in drug costs for N/A beneficiaries.
Where is Nathan Nowalk, M.D. located? ▼
Nathan Nowalk, M.D. is located at 5841 S MARYLAND AVE, Chicago, IL, 60637. Phone: (888) 824-0200.
What is Nathan Nowalk, M.D.'s NPI number? ▼
Nathan Nowalk, M.D.'s National Provider Identifier (NPI) is 1003298720, issued on 06/18/2015.
Does Nathan Nowalk, M.D. prescribe more brand-name or generic drugs? ▼
Nathan Nowalk, M.D.'s prescribing is 58% brand-name and 42% generic drugs by claim count, with $59K in brand drug costs.
How many Sleep Medicine (Internal Medicine) Physician providers are there in the US? ▼
There are 859 Sleep Medicine (Internal Medicine) Physician providers across 52 states in the US. The average Sleep Medicine (Internal Medicine) Physician provider writes 1,310 Medicare Part D claims per year.
What drugs does Nathan Nowalk, M.D. prescribe most often? ▼
Based on 2023 Medicare Part D data, Nathan Nowalk, M.D.'s most frequently prescribed drugs include Anoro Ellipta, Albuterol Sulfate Hfa, Dupixent Syringe. This reflects Medicare Part D prescriptions only and does not include commercial insurance or other payer types.
Does Nathan Nowalk, M.D. accept Medicare? ▼
Nathan Nowalk, M.D. appears in CMS Medicare data with 69 Part D claims and N/A Medicare beneficiaries in 2023. Contact the provider's office directly to confirm current Medicare enrollment and accepted plans.
How can I verify Nathan Nowalk, M.D.'s credentials? ▼
Nathan Nowalk, M.D.'s NPI is 1003298720 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.