2026 NPPES data Internal Medicine Physician NPI 1336342450 M.D.
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LEO MAFFEY, M.D.

Internal Medicine Physician in SYLMAR, California. 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
5K
Medicare Part D claims · 447 beneficiaries · Internal Medicine Physician avg: 3K
Generic prescribing
89%
generic claims · 11% brand-name · higher generic rates reduce patient out-of-pocket costs

What the federal data shows

LEO MAFFEY, M.D. filed 4,712 Medicare Part D claims in 2023 as a Internal Medicine Physician in SYLMAR, California, prescribing 89% generic.

5K
Part D claims, 2023
89%
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.

LEO MAFFEY, M.D.'s Medicare Part D volume vs every U.S. prescriber

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

4,712 Top 7% higher than 93% 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%). Below this entry. 600–800: 56,224 prescribers (4%). Below this entry. 800–1,000: 40,919 prescribers (3%). Below this entry. 1,000–1,200: 31,827 prescribers (2%). Below this entry. 1,200–1,400: 26,224 prescribers (2%). Below this entry. 1,400–1,600: 21,710 prescribers (2%). Below this entry. 1,600–1,800: 19,072 prescribers (1%). Below this entry. 1,800–2,000: 16,451 prescribers (1%). Below this entry. 2,000–2,200: 213,991 prescribers (16%). This entry sits in this band. 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)

LEO MAFFEY, 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 LEO MAFFEY, M.D.?

Quality data not reported

NPI registry status

Active

Issued 06/06/2007

NPI 1336342450

Primary specialty

Internal Medicine Physician

High-volume

172,858 US NPIs in this specialty

Medicare Part D claims

4,712 73% vs specialty avg

2023 prescription claims

Specialty avg: 2,716

Specialty distribution in California

How Internal Medicine Physician compares to other specialties among California providers

California providers

Internal Medicine Physician share within California

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

Specialty board-certification context

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

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

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

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

LEO MAFFEY, M.D. appears in the CMS NPPES registry as a Internal Medicine Physician provider holding M.D. credentials at 14445 OLIVE VIEW DR RM 6B119-H, SYLMAR, CA, 91342, with a listed phone of (818) 364-3031. NPI 1336342450 was issued on 06/06/2007. Because NPPES data is self-reported by the provider and refreshed monthly, the address, phone, and specialty reflect what MAFFEY 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 4,712 prescription claims written by this provider, covering 447 Medicare beneficiaries and totaling roughly $278K in drug spend, split 11% brand-name and 89% generic by claim count, with an opioid prescribing rate of 4.3%. 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.

Internal Medicine Physician is a high-volume specialty nationwide, with 172,858 enrolled providers across 56 states and an average of 2,716 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

14445 OLIVE VIEW DR RM 6B119-H
SYLMAR, CA 91342

Provider Details

NPI 1336342450
Specialty Internal Medicine Physician
Credentials M.D.
Gender Male
NPI Issued 06/06/2007

Hospital and facility affiliations

Facilities where LEO MAFFEY, 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.

SOUTHERN CALIFORNIA PERMANENTE MEDICAL GROUP
GARDEN GROVE, CA

Affiliations sourced from CMS Doctors and Clinicians National Downloadable File; hospital ratings from CMS Hospital General Information dataset (cross-referenced by facility name + state).

License & disciplinary context — California MBC 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 ~150K California medical licensees in 2023 — they are NOT specific to LEO MAFFEY, M.D.. To verify LEO MAFFEY, M.D.'s current license status, search the MBC public license lookup directly, or check the Federation of State Medical Boards (FSMB) verification service.

576
Total board actions, California 2023
Across 556 cases
3.84
Actions per 1,000 licensees
California statewide rate
probation
Most common action type
186 cases

MBC 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 California disciplinary trends page. Cross-checked against FSMB U.S. Medical Regulatory Trends.

Brand vs generic prescribing mix · Typical

LEO MAFFEY, M.D. — brand share 11.0%
Specialty average (est.)

11% brand-name claims vs 89% generic, on 4,712 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.

4,712
Total Claims
$278K
Total Drug Cost
447
Medicare Beneficiaries

Prescribing Breakdown

30-Day Fills
12,382
Total Day Supply
360,925
Brand vs Generic
11% brand / 89% generic
Brand Drug Cost
$196K
Generic Drug Cost
$79K
Opioid Claims
201 (4.3% rate)
Antibiotic Claims
99

Patient Demographics

Average Patient Age
74.8 years
Avg HCC Risk Score
1.38
Gender Split
51% female / 49% male
Age Distribution
<65: 18, 65-74: 215, 75-84: 151, 85+: 63

Top Prescribed Drugs (Medicare Part D)

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

What LEO MAFFEY, 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
Atorvastatin Calcium
266
Losartan Potassium
201
Amlodipine Besylate
198
Pravastatin Sodium
185
Lisinopril
178
Rosuvastatin Calcium
171
Levothyroxine Sodium
153
Metformin Hcl Er
Metformin Hcl
110
Atenolol
101
Metoprolol Tartrate
101

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

Internal Medicine Physician Overview

How LEO MAFFEY, M.D. fits within the Internal Medicine Physician landscape nationally.

172,858
Internal Medicine Physician Providers in US
56
States with Internal Medicine Physician
2,716
Avg Claims per Provider

LEO MAFFEY, M.D.'s 4,712 claims are above the specialty average of 2,716.

Nearby Internal Medicine Physician Providers in California

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

Compare Internal Medicine Physician nationally: see state-by-state distribution →

Frequently Asked Questions

What is LEO MAFFEY, M.D.'s specialty?
LEO MAFFEY, M.D. specializes in Internal Medicine Physician and practices in SYLMAR, California. Credentials: M.D..
How much does LEO MAFFEY, M.D. prescribe under Medicare Part D?
In 2023, LEO MAFFEY, M.D. wrote 4,712 Medicare Part D claims totaling $278K in drug costs for 447 beneficiaries.
Where is LEO MAFFEY, M.D. located?
LEO MAFFEY, M.D. is located at 14445 OLIVE VIEW DR RM 6B119-H, SYLMAR, CA, 91342. Phone: (818) 364-3031.
What is LEO MAFFEY, M.D.'s NPI number?
LEO MAFFEY, M.D.'s National Provider Identifier (NPI) is 1336342450, issued on 06/06/2007.
Does LEO MAFFEY, M.D. prescribe more brand-name or generic drugs?
LEO MAFFEY, M.D.'s prescribing is 11% brand-name and 89% generic drugs by claim count, with $196K in brand drug costs.
Does LEO MAFFEY, M.D. prescribe opioids?
Yes, LEO MAFFEY, M.D. had 201 opioid claims in 2023 with an opioid prescribing rate of 4.3%.
How many Internal Medicine Physician providers are there in the US?
There are 172,858 Internal Medicine Physician providers across 56 states in the US. The average Internal Medicine Physician provider writes 2,716 Medicare Part D claims per year.
What drugs does LEO MAFFEY, M.D. prescribe most often?
Based on 2023 Medicare Part D data, LEO MAFFEY, M.D.'s most frequently prescribed drugs include Atorvastatin Calcium, Losartan Potassium, Amlodipine Besylate. This reflects Medicare Part D prescriptions only and does not include commercial insurance or other payer types.
Does LEO MAFFEY, M.D. accept Medicare?
LEO MAFFEY, M.D. appears in CMS Medicare data with 4,712 Part D claims and 447 Medicare beneficiaries in 2023. Contact the provider's office directly to confirm current Medicare enrollment and accepted plans.
How can I verify LEO MAFFEY, M.D.'s credentials?
LEO MAFFEY, M.D.'s NPI is 1336342450 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