Rosa Ahn-Horst, MD MPH
NPI 1649822420 · Psychiatry Physician · Palo Alto, CA
Enrolled with Medicare as Order and Referring Only - Psychiatry · source: CMS PECOS Public Provider Enrollment (2026.04.01)
Rosa Ahn-Horst, MD MPH is a Psychiatry Physician provider in Palo Alto, CA (NPI 1649822420).
Provider details
- NPI number
- 1649822420
- Entity type
- Individual
- Primary specialty
- Psychiatry PhysicianAllopathic & Osteopathic Physicians
- Credential
- MD MPH
- Sex
- Female
- Sole proprietor
- No
- License
- A201644 (CA)
Specialties & taxonomies
Allopathic & Osteopathic Physicians
Student, Health Care
Profile Score
A profile completeness & documented-activity index — NOT a quality, outcomes, or patient-satisfaction rating.
- Registry tenure38% of score
6 yrs in NPPES registry
- Profile completeness38% of score
100% of core fields populated
- Practice footprint23% of score
1 documented practice location
Signals a provider has no public data for (e.g. Medicare claims) are left out of the score entirely — never counted as zero — so providers without that data are not penalized. See the full formula and weights in our methodology.
What this provider prescribes (Medicare Part D)
Top drugs by Medicare Part D claim volume, 2024 · 4 distinct drugs on file.
| Drug | Part D claims (2024) |
|---|---|
| Lurasidone Hcl | 15 |
| Lithium Carbonatebrand: Lithium Carbonate Er | 13 |
| Bupropion Hclbrand: Bupropion Xl | 13 |
| Clonazepam | 11 |
Medicare Part D only. These counts cover prescriptions paid through Medicare Part D in 2024 — they do notinclude cash-pay, commercial-insurance, Medicaid, or Part B–administered drugs, and badly undercount high cash-pay categories (e.g. GLP-1 weight-loss, testosterone, and ED medications). Any drug with 10 or fewer claims is omitted by CMS, and beneficiary counts under 11 are suppressed — so a missing drug means no Part D record, never zero. This is a factual claims summary, not an endorsement, not medical advice, and not a consumer report. Source: CMS Medicare Part D Prescribers — by Provider and Drug.
Practice location
Mailing address
Registry dates
- Enumerated
- 2019-07-12
- Last updated
- 2025-11-06
- Certified
- 2025-11-06
Frequently asked questions
- What is Rosa Ahn-Horst's NPI number?
- Rosa Ahn-Horst's National Provider Identifier (NPI) is 1649822420, a unique 10-digit ID issued by CMS for use in standard healthcare transactions.
- What is Rosa Ahn-Horst's specialty?
- Rosa Ahn-Horst is listed in the NPPES registry with a primary specialty of Psychiatry Physician (Allopathic & Osteopathic Physicians).
- Where is Rosa Ahn-Horst located?
- Rosa Ahn-Horst's practice location on file with NPPES is 401 Quarry Rd, Palo Alto, CA 94304-1419.
- What is Rosa Ahn-Horst's phone number?
- The practice phone number listed in the NPPES registry for Rosa Ahn-Horst is (650) 723-5511.
- Does Rosa Ahn-Horst accept Medicare?
- Rosa Ahn-Horst is approved to bill Medicare according to CMS PECOS enrollment data (2026.04.01). Confirm current participation with the provider before scheduling.
- Is Rosa Ahn-Horst's NPI active?
- Yes — Rosa Ahn-Horst's NPI (1649822420) is active in the NPPES registry as of the last update on 2025-11-06.
Source: CMS NPPES Data Dissemination (June 2026). NPI Central is not affiliated with CMS. Data is provided as-is from the public registry.