2026 NPPES data Obstetrics & Gynecology Physician NPI 1679653786 M.D.
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JACEK KOWALSKI, M.D.

Obstetrics & Gynecology Physician in WEST ALLIS, 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
202
Medicare Part D claims · 54 beneficiaries · Obstetrics & Gynecology Physician avg: 179
Generic prescribing
87%
generic claims · 13% brand-name · higher generic rates reduce patient out-of-pocket costs

What the federal data shows

JACEK KOWALSKI, M.D. filed 202 Medicare Part D claims in 2023 as a Obstetrics & Gynecology Physician in WEST ALLIS, Wisconsin, prescribing 87% generic.

202
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.

JACEK KOWALSKI, M.D.'s Medicare Part D volume vs every U.S. prescriber

Total Medicare Part D claims, 2023 — across all CMS prescribers nationally

202 49th percentile higher than 49% of 1,370,886 prescribers

0–200: 670,926 prescribers (49%). Below this entry. 200–400: 182,923 prescribers (13%). This entry sits in this band. 400–600: 90,619 prescribers (7%). Above this entry. 600–800: 56,224 prescribers (4%). Above this entry. 800–1,000: 40,919 prescribers (3%). Above this entry. 1,000–1,200: 31,827 prescribers (2%). Above this entry. 1,200–1,400: 26,224 prescribers (2%). Above this entry. 1,400–1,600: 21,710 prescribers (2%). Above this entry. 1,600–1,800: 19,072 prescribers (1%). Above this entry. 1,800–2,000: 16,451 prescribers (1%). Above this entry. 2,000–2,200: 213,991 prescribers (16%). Above this entry. 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)

JACEK KOWALSKI, M.D. 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 JACEK KOWALSKI, M.D.?

Quality data not reported

NPI registry status

Active

Issued 10/16/2006

NPI 1679653786

Primary specialty

Obstetrics & Gynecology Physician

Mid-sized

44,313 US NPIs in this specialty

Medicare Part D claims

202 13% vs specialty avg

2023 prescription claims

Specialty avg: 179

Specialty distribution in Wisconsin

How Obstetrics & Gynecology Physician compares to other specialties among Wisconsin providers

Wisconsin providers

Obstetrics & Gynecology Physician share within Wisconsin

1. Obstetrics & Gynecology Physician42%2. Internal medicine21%3. Family medicine17%4. Surgical12%5. Pediatric8%
Obstetrics & Gynecology Physician share within Wisconsin

Specialty board-certification context

Estimated specialty board-certified rate — Obstetrics & Gynecology Physician (ABMS / AOA reference)

Quality data not reported
Est. board-certified rate
78%
Obstetrics & Gynecology Physician ABMS/AOA estimate

Est. board-certified rate (Obstetrics & Gynecology Physician) — ABMS / AOA estimate

0%100%78%
Est. board-certified rate (Obstetrics & Gynecology 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).

JACEK KOWALSKI, M.D. appears in the CMS NPPES registry as a Obstetrics & Gynecology Physician provider holding M.D. credentials at 8905 W LINCOLN AVE, WEST ALLIS, WI, 53227, with a listed phone of (414) 978-2229. NPI 1679653786 was issued on 10/16/2006. Because NPPES data is self-reported by the provider and refreshed monthly, the address, phone, and specialty reflect what KOWALSKI 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 202 prescription claims written by this provider, covering 54 Medicare beneficiaries and totaling roughly $16K in drug spend, split 13% brand-name and 87% generic by claim count. 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.

Obstetrics & Gynecology Physician is a mid-sized specialty nationwide, with 44,313 enrolled providers across 56 states and an average of 179 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

8905 W LINCOLN AVE
WEST ALLIS, WI 53227

Provider Details

NPI 1679653786
Specialty Obstetrics & Gynecology Physician
Credentials M.D.
Gender Male
NPI Issued 10/16/2006

Hospital and facility affiliations

Facilities where JACEK KOWALSKI, 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.

AURORA ADVANCED HEALTHCARE, INC.
WEST ALLIS, 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).

Brand vs generic prescribing mix · Typical

JACEK KOWALSKI, M.D. — brand share 13.0%
Specialty average (est.)

13% brand-name claims vs 87% generic, on 202 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.

202
Total Claims
$16K
Total Drug Cost
54
Medicare Beneficiaries

Prescribing Breakdown

30-Day Fills
278
Total Day Supply
6,393
Brand vs Generic
13% brand / 87% generic
Brand Drug Cost
$5K
Generic Drug Cost
$11K
Antibiotic Claims
27

Patient Demographics

Average Patient Age
69.4 years
Avg HCC Risk Score
1.19
Gender Split
100% female / 0% male

Top Prescribed Drugs (Medicare Part D)

Top drugs by claim count for calendar year 2023. Based on Medicare Part D data only.

What JACEK KOWALSKI, M.D. 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
Fluconazole
46
Estradiol
33
Clotrimazole-Betamethasone
Clotrimazole/Betamethasone Dip
21
Metronidazole
12
Estradiol (Once Weekly)
Estradiol
11
Premarin
"Estrogens
N/A

* Counts below 11 are suppressed by CMS for patient privacy. Generic names shown where available from CMS Part D data.

Obstetrics & Gynecology Physician Overview

How JACEK KOWALSKI, M.D. fits within the Obstetrics & Gynecology Physician landscape nationally.

44,313
Obstetrics & Gynecology Physician Providers in US
56
States with Obstetrics & Gynecology Physician
179
Avg Claims per Provider

JACEK KOWALSKI, M.D.'s 202 claims are above the specialty average of 179.

Nearby Obstetrics & Gynecology Physician Providers in Wisconsin

Other clinicians with the same primary specialty enrolled in Wisconsin, drawn from the same CMS NPPES roster as KOWALSKI.

Compare Obstetrics & Gynecology Physician nationally: see state-by-state distribution →

Frequently Asked Questions

What is JACEK KOWALSKI, M.D.'s specialty?
JACEK KOWALSKI, M.D. specializes in Obstetrics & Gynecology Physician and practices in WEST ALLIS, Wisconsin. Credentials: M.D..
How much does JACEK KOWALSKI, M.D. prescribe under Medicare Part D?
In 2023, JACEK KOWALSKI, M.D. wrote 202 Medicare Part D claims totaling $16K in drug costs for 54 beneficiaries.
Where is JACEK KOWALSKI, M.D. located?
JACEK KOWALSKI, M.D. is located at 8905 W LINCOLN AVE, WEST ALLIS, WI, 53227. Phone: (414) 978-2229.
What is JACEK KOWALSKI, M.D.'s NPI number?
JACEK KOWALSKI, M.D.'s National Provider Identifier (NPI) is 1679653786, issued on 10/16/2006.
Does JACEK KOWALSKI, M.D. prescribe more brand-name or generic drugs?
JACEK KOWALSKI, M.D.'s prescribing is 13% brand-name and 87% generic drugs by claim count, with $5K in brand drug costs.
How many Obstetrics & Gynecology Physician providers are there in the US?
There are 44,313 Obstetrics & Gynecology Physician providers across 56 states in the US. The average Obstetrics & Gynecology Physician provider writes 179 Medicare Part D claims per year.
What drugs does JACEK KOWALSKI, M.D. prescribe most often?
Based on 2023 Medicare Part D data, JACEK KOWALSKI, M.D.'s most frequently prescribed drugs include Fluconazole, Estradiol, Clotrimazole-Betamethasone. This reflects Medicare Part D prescriptions only and does not include commercial insurance or other payer types.
Does JACEK KOWALSKI, M.D. accept Medicare?
JACEK KOWALSKI, M.D. appears in CMS Medicare data with 202 Part D claims and 54 Medicare beneficiaries in 2023. Contact the provider's office directly to confirm current Medicare enrollment and accepted plans.
How can I verify JACEK KOWALSKI, M.D.'s credentials?
JACEK KOWALSKI, M.D.'s NPI is 1679653786 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

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