Stephen O'Brien, M.D.
NPI 1699794453 · Internal Medicine Physician · Oakland, CA
Stephen O'Brien, M.D. is a Internal Medicine Physician provider in Oakland, CA (NPI 1699794453).
Provider details
- NPI number
- 1699794453
- Entity type
- Individual
- Primary specialty
- Internal Medicine PhysicianAllopathic & Osteopathic Physicians
- Credential
- M.D.
- Sex
- Male
- Sole proprietor
- No
- License
- G74654 (CA)
Specialties & taxonomies
Allopathic & Osteopathic Physicians
Profile Score
A profile completeness & documented-activity index — NOT a quality, outcomes, or patient-satisfaction rating.
- Registry tenure38% of score
19 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 · 26 distinct drugs on file.
| Drug | Part D claims (2024) |
|---|---|
| Bictegrav/Emtricit/Tenofov Alabrand: Biktarvy | 71 |
| Atorvastatin Calcium | 38 |
| Testosterone | 35 |
| Hydrocodone/Acetaminophenbrand: Hydrocodone-Acetaminophen | 30 |
| Acyclovir | 27 |
| Raltegravir Potassiumbrand: Isentress | 26 |
| Abacavir Sulfate/Lamivudinebrand: Abacavir-Lamivudine | 24 |
| Lisinopril | 22 |
Practice location
Mailing address
Registry dates
- Enumerated
- 2006-07-19
- Last updated
- 2007-07-08
Frequently asked questions
- What is Stephen O'Brien's NPI number?
- Stephen O'Brien's National Provider Identifier (NPI) is 1699794453, a unique 10-digit ID issued by CMS for use in standard healthcare transactions.
- What is Stephen O'Brien's specialty?
- Stephen O'Brien is listed in the NPPES registry with a primary specialty of Internal Medicine Physician (Allopathic & Osteopathic Physicians).
- Where is Stephen O'Brien located?
- Stephen O'Brien's practice location on file with NPPES is 3100 Summitt Street, Oakland, CA 94609-0000.
- What is Stephen O'Brien's phone number?
- The practice phone number listed in the NPPES registry for Stephen O'Brien is (510) 869-8400.
- Is Stephen O'Brien's NPI active?
- Yes — Stephen O'Brien's NPI (1699794453) is active in the NPPES registry as of the last update on 2007-07-08.
Source: CMS NPPES Data Dissemination (June 2026). NPI Central is not affiliated with CMS. Data is provided as-is from the public registry.