Zachary Gerard O'Leary, PA-C
Physician Assistant · Castro Valley, CA
Zachary Gerard O'Leary, PA-C is a physician assistant with a practice address in Castro Valley, California, and NPI 1083298178, issued on May 6, 2021. Check the license (California PA59454, as entered in NPPES) with the California board that licenses this profession; the Medicare figures below come from public CMS files.
- Name
- Zachary Gerard O'Leary
- Credential
- PA-C
- Primary taxonomy
- Physician Assistant 363A00000X
- License number
- PA59454 CA
Self-reported in NPPES; status is on the state search - Practice location
- 20642 John Dr, Castro Valley, CA 94546
- Phone
- (888) 924-1036
- Enumerated
- May 6, 2021
- Record last updated
- Nov 28, 2023
- Medicare enrollment
- Enrolled (PECOS I20210629001835); accepts Medicare assignment
- Medical or professional school
- Stanford University School Of Medicine, 2021
- Telehealth
- Offers telehealth (CMS)
- Entity
- Type 1 · individual
8 nearest physician assistant records → All 14,451 in California → Look up another NPI →
Also registered at 20642 John Dr
A shared address usually means a shared clinic or building; it does not show who employs whom.
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- Shiven Chaudhry, MDInternal Medicine Physician1528594801
- Corina Clark, P.A.Physician Assistant1720480049
- Ashley Etchison, MDDiagnostic Radiology Physician1962907840
Verify Zachary Gerard O'Leary in five checks
- 1IdentityNPI record in CMS NPPESNPI lookupConfirmed in NPPES
- 2LicenseActive license and public ordersWhich California board licenses this profession
Search for license PA59454Check the board - 3Other statesLicenses and actions elsewhereDocInfo (FSMB)Not checked
- 4ExclusionsMedicare and Medicaid bansHHS-OIG exclusion listNot checked
- 5CertificationBoard certificationABMS AOA NCCPA AANPNot checked
6.9 times the Medicare Part D claims of the average physician assistant in 2024
5,711 Medicare Part D claims for 1,230 beneficiaries, against an average of 830 among the 101,058 providers of this specialty who prescribed in Part D. Brand-name drugs were 10% of claims. 97 claims were for opioids.
Most prescribed
- Atorvastatin Calcium465 claims
- Amlodipine Besylate316 claims
- Levothyroxine Sodium265 claims
- Losartan Potassium237 claims
- Lisinopril222 claims
- Metformin Hcl162 claims
Source: CMS Medicare Part D Prescribers by Provider and Drug, 2024 (data.cms.gov). Part D covers prescriptions for Medicare patients only; drugs with fewer than 11 claims are not published.
The MIPS final score for 2023 (Medicare payment program): 94.9 of 100
The Merit-based Incentive Payment System score is reported for this clinician. Four categories are weighted into the final score; the average among 454,083 clinicians with a measured score was 83.5.
Source: CMS Quality Payment Program, MIPS performance year 2023; category weights for 2023 (qpp.cms.gov).
Bills Medicare through one group practice
- University Healthcare AllianceCastro Valley, CA
Source: CMS Doctors and Clinicians National Downloadable File (the group practices a clinician bills Medicare through) (data.cms.gov).
Zachary Gerard O'Leary among 14,451 physician assistant records in California
Zachary Gerard O'Leary, PA-C is one of 14,451 physician assistant records with a practice address in California. 75% of them appear in a Medicare file (Part D prescribing, MIPS, Open Payments or Medicare group billing); this one does. Its NPI, issued in 2021, is newer than 67% of them.
- NPI issued2021 · 67% of these records are older, 27% newer
- In a Medicare fileYes · 75% of these records are
- In the CMS Doctors and Clinicians fileYes · 50% of these records are
- Graduated2021 · median 2018 among the 7,214 with a school on file
- Record last updated2023 · 40% of these records were not updated in five years or more
Source: CMS NPPES, file of Aug 9, 2026, every record with primary taxonomy 363A00000X and a California practice address; Medicare files: CMS Part D Prescribers 2024, MIPS 2023, Open Payments 2024, Doctors and Clinicians (data.cms.gov).
28 physician assistant records list a practice address in Castro Valley
They are 28 of the 999 NPPES records with a practice address in Castro Valley, and 14,451 physician assistant records in California.
All 14,451 in California → Every provider in Castro Valley → Physician Assistant nationwide →
The 8 physician assistant records with the nearest ZIP codes
- Eric Bellfort, PACastro Valley, CA 945461073504403
- Cherie Clark, PA-CCastro Valley, CA 945461780992560
- Barry Clements, PA-CCastro Valley, CA 945461952392177
- Melissa Goralka, PACastro Valley, CA 945461891878740
- Jasmine Halloran, PACCastro Valley, CA 945461124090162
- Patti Hee, PA-CCastro Valley, CA 945461851439145
- Isaac Ibrahimi, PA-CCastro Valley, CA 945461588735849
- Shalini Jeyakumar, MPA, RPA-CCastro Valley, CA 945461801119995
Common questions
What is Zachary Gerard O'Leary, PA-C's NPI number?
Zachary Gerard O'Leary, PA-C's National Provider Identifier (NPI) is 1083298178, issued on May 6, 2021. An NPI identifies a provider in billing; it is not a license.
Where is Zachary Gerard O'Leary, PA-C located?
The NPPES record lists a practice address at 20642 John Dr, Castro Valley, CA, 94546. Phone: (888) 924-1036. Providers update this record themselves, so call before visiting.
How can I verify Zachary Gerard O'Leary, PA-C's license?
NPPES lists California license number PA59454, as entered by the provider. Search the California board that licenses this profession; the NPPES record confirms identity only.
How much does Zachary Gerard O'Leary, PA-C prescribe under Medicare Part D?
In 2024, Zachary Gerard O'Leary, PA-C had 5,711 Medicare Part D claims for 1,230 beneficiaries; the average among physician assistant prescribers was 830. Part D covers Medicare prescriptions only.
What is Zachary Gerard O'Leary, PA-C's MIPS final score?
The 2023 MIPS final score is 94.9 of 100. The average among 454,083 clinicians with a measured score was 83.5.
Source: CMS National Plan and Provider Enumeration System (NPPES), file of Aug 9, 2026 (NPPES files on CMS.gov); NUCC Health Care Provider Taxonomy. Medicare files from data.cms.gov. An NPI identifies who bills; it is not a license.
Figures on PlainDoctor are read from the federal files each page names (CMS NPPES, Medicare Part D, MIPS, Open Payments; the HHS-OIG exclusion list only as counts) and from Census population estimates, with the file date shown beside them. See our editorial standards & corrections policy, the methodology behind these numbers, or report a data error. Data current as of Aug 9, 2026.