2026 NPPES data Pediatrics Physician NPI 1558384438 MD
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Karen Williams, MD

Pediatrics Physician in Oak Bluffs, Massachusetts. 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
283
Medicare Part D claims · 39 beneficiaries · Pediatrics Physician avg: 762
Generic prescribing
91%
generic claims · 9% brand-name · higher generic rates reduce patient out-of-pocket costs

What the federal data shows

Karen Williams, MD filed 283 Medicare Part D claims in 2023 as a Pediatrics Physician in Oak Bluffs, Massachusetts, prescribing 91% generic.

283
Part D claims, 2023
91%
generic prescribing

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.

Karen Williams, MD's Medicare Part D volume vs every U.S. prescriber

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

283 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-eligible specialty (heuristic — not verified)

Karen Williams, MD practices in an ABMS-board-eligible specialty but we don't have enough CMS-participation signals to confirm active board-certified status. Consult CertificationMatters.org (the official ABMS public lookup).

What does the federal data show about Karen Williams, MD?

Quality data not reported

NPI registry status

Active

Issued 07/25/2006

NPI 1558384438

Primary specialty

Pediatrics Physician

High-volume

80,574 US NPIs in this specialty

Medicare Part D claims

283 63% vs specialty avg

2023 prescription claims

Specialty avg: 762

Specialty distribution in Massachusetts

How Pediatrics Physician compares to other specialties among Massachusetts providers

Massachusetts providers

Pediatrics Physician share within Massachusetts

1. Pediatrics Physician42%2. Internal medicine21%3. Family medicine17%4. Surgical12%5. Pediatric8%
Pediatrics Physician share within Massachusetts

Specialty board-certification context

Estimated specialty board-certified rate — Pediatrics Physician (ABMS / AOA reference)

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

Est. board-certified rate (Pediatrics Physician) — ABMS / AOA estimate

0%100%78%
Est. board-certified rate (Pediatrics 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).

Karen Williams, MD appears in the CMS NPPES registry as a Pediatrics Physician provider holding MD credentials at MARTHA'S VINEYARD HOSPITAL, Oak Bluffs, MA, 02557, with a listed phone of (508) 693-3732. NPI 1558384438 was issued on 07/25/2006. Because NPPES data is self-reported by the provider and refreshed monthly, the address, phone, and specialty reflect what Williams 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 283 prescription claims written by this provider, covering 39 Medicare beneficiaries and totaling roughly $16K in drug spend, split 9% brand-name and 91% 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.

Pediatrics Physician is a high-volume specialty nationwide, with 80,574 enrolled providers across 56 states and an average of 762 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

MARTHA'S VINEYARD HOSPITAL
Oak Bluffs, MA 02557

Provider Details

NPI 1558384438
Specialty Pediatrics Physician
Credentials MD
Gender Female
NPI Issued 07/25/2006

License & disciplinary context — Massachusetts BORIM 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 ~38K Massachusetts medical licensees in 2023 — they are NOT specific to Karen Williams, MD. To verify Karen Williams, MD's current license status, search the BORIM public license lookup directly, or check the Federation of State Medical Boards (FSMB) verification service.

80
Total board actions, Massachusetts 2023
Across 78 cases
2.11
Actions per 1,000 licensees
Massachusetts statewide rate
probation
Most common action type
29 cases

BORIM 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 Massachusetts disciplinary trends page. Cross-checked against FSMB U.S. Medical Regulatory Trends.

Brand vs generic prescribing mix · Generic-heavy

Karen Williams, MD — brand share 9.0%
Specialty average (est.)

9% brand-name claims vs 91% generic, on 283 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.

283
Total Claims
$16K
Total Drug Cost
39
Medicare Beneficiaries

Prescribing Breakdown

30-Day Fills
612
Total Day Supply
17,614
Brand vs Generic
9% brand / 91% generic
Brand Drug Cost
$11K
Generic Drug Cost
$4K

Patient Demographics

Average Patient Age
73.2 years
Avg HCC Risk Score
1.07
Age Distribution
<65: 0, 65-74: 23, 75-84: 16, 85+: 0

Top Prescribed Drugs (Medicare Part D)

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

What Karen Williams, 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
31
Lisinopril
20
Amlodipine Besylate
17
Metformin Hcl
17
Clonazepam
11
Lexapro
Escitalopram Oxalate
11
Nano 2nd Gen Pen Needle
"Pen Needle
N/A

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

Pediatrics Physician Overview

How Karen Williams, MD fits within the Pediatrics Physician landscape nationally.

80,574
Pediatrics Physician Providers in US
56
States with Pediatrics Physician
762
Avg Claims per Provider

Karen Williams, MD's 283 claims are below the specialty average of 762.

Nearby Pediatrics Physician Providers in Massachusetts

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

Compare Pediatrics 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 Massachusetts medical board — federal registration is not a license check. Credential verification guide
  • Weigh a second option: compare this provider with a nearby Pediatrics 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.

Frequently Asked Questions

What is Karen Williams, MD's specialty?
Karen Williams, MD specializes in Pediatrics Physician and practices in Oak Bluffs, Massachusetts. Credentials: MD.
How much does Karen Williams, MD prescribe under Medicare Part D?
In 2023, Karen Williams, MD wrote 283 Medicare Part D claims totaling $16K in drug costs for 39 beneficiaries.
Where is Karen Williams, MD located?
Karen Williams, MD is located at MARTHA'S VINEYARD HOSPITAL, Oak Bluffs, MA, 02557. Phone: (508) 693-3732.
What is Karen Williams, MD's NPI number?
Karen Williams, MD's National Provider Identifier (NPI) is 1558384438, issued on 07/25/2006.
Does Karen Williams, MD prescribe more brand-name or generic drugs?
Karen Williams, MD's prescribing is 9% brand-name and 91% generic drugs by claim count, with $11K in brand drug costs.
How many Pediatrics Physician providers are there in the US?
There are 80,574 Pediatrics Physician providers across 56 states in the US. The average Pediatrics Physician provider writes 762 Medicare Part D claims per year.
What drugs does Karen Williams, MD prescribe most often?
Based on 2023 Medicare Part D data, Karen Williams, MD's most frequently prescribed drugs include Atorvastatin Calcium, Lisinopril, Amlodipine Besylate. This reflects Medicare Part D prescriptions only and does not include commercial insurance or other payer types.
Does Karen Williams, MD accept Medicare?
Karen Williams, MD appears in CMS Medicare data with 283 Part D claims and 39 Medicare beneficiaries in 2023. Contact the provider's office directly to confirm current Medicare enrollment and accepted plans.
How can I verify Karen Williams, MD's credentials?
Karen Williams, MD's NPI is 1558384438 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