2026 NPPES data Physician Assistant NPI 1952017857 PA
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Katherine Castillo, PA

Physician Assistant in Libertyville, 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 149,975 in Physician Assistant, 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
551
Medicare Part D claims · 159 beneficiaries · Physician Assistant avg: 790
Industry payments
$2.1K
105 payments · CMS Open Payments (Sunshine Act)
Compiled from official public sources by the PlainDoctor editorial team.

What the federal data shows

Katherine Castillo, PA filed 551 Medicare Part D claims in 2023 as a Physician Assistant in Libertyville, Illinois.

551
Part D claims, 2023
$2.1K
industry payments (Sunshine Act)

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.

Katherine Castillo, PA's Medicare Part D volume vs every U.S. prescriber

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

551 Top 34% higher than 66% 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%). This entry sits in this band. 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. 2K+: 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

What does the federal data show about Katherine Castillo, PA?

Quality data not reported

NPI registry status

Active

Issued 01/25/2023

NPI 1952017857

Primary specialty

Physician Assistant

High-volume

149,975 US NPIs in this specialty

Medicare Part D claims

551 30% vs specialty avg

2023 prescription claims

Specialty avg: 790

Specialty distribution in Illinois

How Physician Assistant compares to other specialties among Illinois providers

Illinois providers

Largest specialties in Illinois (% of in-state providers)

Clinical Social Worker - 5.2%Clinical Social Worker5.2%Physical Therapist - 5%Physical Therapist5%Mental Health Counselor - 4.5%Mental Health Counselor4.5%Speech-Language Pathologist - 4.2%Speech-Language Pathologist4.2%Student in an Organized Health Care Education/Training Program - 4.2%Student in an Organized Health Care Education/Training Program4.2%Pharmacist - 4.1%Pharmacist4.1%Physician Assistant - 1.9%Physician Assistant1.9%
Largest specialties in Illinois (% of in-state 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 Physician Assistant. Verify directly:

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).

Katherine Castillo, PA appears in the CMS NPPES registry as a Physician Assistant provider holding PA credentials at 1850 W WINCHESTER RD, Libertyville, IL, 60048, with a listed phone of (847) 362-9050. NPI 1952017857 was issued on 01/25/2023. Because NPPES data is self-reported by the provider and refreshed monthly, the address, phone, and specialty reflect what Castillo 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 551 prescription claims written by this provider, covering 159 Medicare beneficiaries and totaling roughly $39K in drug spend. 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.

Physician Assistant is a high-volume specialty nationwide, with 149,975 enrolled providers across 56 states and an average of 790 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

1850 W WINCHESTER RD
Libertyville, IL 60048

Provider Details

NPI 1952017857
Specialty Physician Assistant
Credentials PA
Gender Female
NPI Issued 01/25/2023

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 Katherine Castillo, PA. Source: openpaymentsdata.cms.gov.

Total received

$2.1K

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 Katherine Castillo, PA. To verify Katherine Castillo, PA'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.

Medicare Part D Prescribing Data

CMS Medicare Part D prescriber-level data for calendar year 2023.

551
Total Claims
$39K
Total Drug Cost
159
Medicare Beneficiaries

Prescribing Breakdown

30-Day Fills
1,213
Total Day Supply
33,582
Generic Drug Cost
$11K
Antibiotic Claims
79

Patient Demographics

Average Patient Age
73.4 years
Avg HCC Risk Score
0.86
Gender Split
55% female / 45% male

Top Prescribed Drugs (Medicare Part D)

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

What Katherine Castillo, PA 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
Rosuvastatin Calcium
46
Atorvastatin Calcium
24
Olmesartan Medoxomil
21
Azithromycin
20
Amlodipine Besylate
18
Fluticasone Propionate
18
Metoprolol Succinate
18
Telmisartan
18
Diclofenac Sodium
17
Amoxicillin-Clavulanate Potass
Amoxicillin/Potassium Clav
13

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

Physician Assistant Overview

How Katherine Castillo, PA fits within the Physician Assistant landscape nationally.

149,975
Physician Assistant Providers in US
56
States with Physician Assistant
790
Avg Claims per Provider

Katherine Castillo, PA's 551 claims are below the specialty average of 790.

Nearby Physician Assistant Providers in Illinois

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

Compare Physician Assistant 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 Physician Assistant 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 Katherine Castillo, PA's specialty?
Katherine Castillo, PA specializes in Physician Assistant and practices in Libertyville, Illinois. Credentials: PA.
How much does Katherine Castillo, PA prescribe under Medicare Part D?
In 2023, Katherine Castillo, PA wrote 551 Medicare Part D claims totaling $39K in drug costs for 159 beneficiaries.
Where is Katherine Castillo, PA located?
Katherine Castillo, PA is located at 1850 W WINCHESTER RD, Libertyville, IL, 60048. Phone: (847) 362-9050.
What is Katherine Castillo, PA's NPI number?
Katherine Castillo, PA's National Provider Identifier (NPI) is 1952017857, issued on 01/25/2023.
How many Physician Assistant providers are there in the US?
There are 149,975 Physician Assistant providers across 56 states in the US. The average Physician Assistant provider writes 790 Medicare Part D claims per year.
What drugs does Katherine Castillo, PA prescribe most often?
Based on 2023 Medicare Part D data, Katherine Castillo, PA's most frequently prescribed drugs include Rosuvastatin Calcium, Atorvastatin Calcium, Olmesartan Medoxomil. This reflects Medicare Part D prescriptions only and does not include commercial insurance or other payer types.
Does Katherine Castillo, PA accept Medicare?
Katherine Castillo, PA appears in CMS Medicare data with 551 Part D claims and 159 Medicare beneficiaries in 2023. Contact the provider's office directly to confirm current Medicare enrollment and accepted plans.
How can I verify Katherine Castillo, PA's credentials?
Katherine Castillo, PA's NPI is 1952017857 with credentials PA. 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

Compiled from official public sources by the PlainDoctor editorial team.