Rosa Ahn-Horst, MD MPH
Psychiatry Physician · Palo Alto, CA
Rosa Ahn-Horst, MD MPH is a psychiatry physician with a practice address in Palo Alto, California, and NPI 1649822420, issued on Jul 12, 2019. Check the license (California A201644, as entered in NPPES) on the Medical Board of California; the Medicare figures below come from public CMS files.
- Name
- Rosa Ahn-Horst
- Credential
- MD MPH
- Primary taxonomy
- Psychiatry Physician 2084P0800X
- License number
- A201644 CA
Self-reported in NPPES; status is on the state search - Practice location
- 401 Quarry RD, Palo Alto, CA 94304
- Phone
- (650) 723-5511
- Enumerated
- Jul 12, 2019
- Entity
- Type 1 · individual
Also registered at 401 Quarry RD
A shared address usually means a shared clinic or building; it does not show who employs whom.
- Richard Abbey, PH.D.Clinical Neuropsychologist1730377649
- Dorothy Adu-Amankwah, MDPsychiatry Physician1932900313
- Nakul AggarwalStudent in an Organized Health Care Education/Training Program1881495976
- Kelley Anderson, M.S., M.A., PHDRehabilitation Counselor1851777999
- Robin Apple, PH.D.Psychologist1134284912
- Sahar AshrafzadehStudent in an Organized Health Care Education/Training Program1871299230
Verify Rosa Ahn-Horst in five checks
- 1IdentityNPI record in CMS NPPESNPI lookupConfirmed in NPPES
- 2LicenseActive license and public ordersMedical Board of California
Search for license A201644Check the board - 3Other statesLicenses and actions elsewhereDocInfo (FSMB)Not checked
- 4ExclusionsMedicare and Medicaid bansHHS-OIG exclusion listNot checked
- 5CertificationBoard certificationABMS, AOA, NCCPA, AANPNot checked
88% fewer Medicare Part D claims than the average psychiatry physician in 2024
122 Medicare Part D claims, against an average of 1,010 among the 32,287 providers of this specialty who prescribed in Part D. Brand-name drugs were 0% of claims.
Most prescribed
- Lurasidone Hcl15 claims
- Bupropion Xl13 claims
- Lithium Carbonate Er13 claims
- Clonazepam11 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.
208 psychiatry physician records list a Palo Alto practice address
They are 208 of the 7,617 NPPES records with a Palo Alto practice address, and 7,890 psychiatry physician records in California.
All 208 in Palo Alto → All 7,890 in California → Every provider in Palo Alto →
Other psychiatry physician records in California
- Nancy Aaen, MDNapa, CA1609816669
- Criselda Abad-Santos, M.D.Woodland Hills, CA1760461826
- Mekabiz Abaian, MDSan Bernardino, CA1891090163
- Kafia Abbasi, M.D.French Camp, CA1215114897
- Michele Abbasi, M.D.Westlake Village, CA1093940330
- Zohaib AbbasiMartinez, CA1013392224
- Chester Abbott, M.D.Pasadena, CA1053442186
- Nancy Abdelmalak, M.D.Elk Grove, CA1912137498
- Ezzat Abdelmalek, M.DDana Point, CA1992828826
- Ahmed AbdelrazekSacramento, CA1669092128
Common questions
What is Rosa Ahn-Horst, MD MPH's NPI number?
Rosa Ahn-Horst, MD MPH's National Provider Identifier (NPI) is 1649822420, issued on Jul 12, 2019. An NPI identifies a provider in billing; it is not a license.
Where is Rosa Ahn-Horst, MD MPH located?
The NPPES record lists a practice address at 401 Quarry RD, Palo Alto, CA, 94304. Phone: (650) 723-5511. Providers update this record themselves, so call before visiting.
How can I verify Rosa Ahn-Horst, MD MPH's license?
NPPES lists California license number A201644, as entered by the provider. Search the Medical Board of California at https://www.mbc.ca.gov/License-Verification/default.aspx. The NPPES record confirms identity only; the state search shows license status, expiration and public orders.
How much does Rosa Ahn-Horst, MD MPH prescribe under Medicare Part D?
In 2024, Rosa Ahn-Horst, MD MPH had 122 Medicare Part D claims; the average among psychiatry physician prescribers was 1,010. Part D covers Medicare prescriptions only.
Source: CMS National Plan and Provider Enumeration System (NPPES), loaded Aug 27, 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.
Every figure on PlainDoctor is rendered directly from the federal CMS NPPES registry, Medicare Part D, MIPS, and Open Payments records, no number is typed in by an editor. See our editorial standards & corrections policy, the methodology behind these numbers, or report a data error. Data current as of Aug 27, 2026.