John O'Brien, M.D.
NPI 1083689061 · Family Medicine Physician · O Fallon, MO
John O'Brien, M.D. is a Family Medicine Physician provider in O Fallon, MO (NPI 1083689061).
Provider details
- NPI number
- 1083689061
- Entity type
- Individual
- Primary specialty
- Family Medicine PhysicianAllopathic & Osteopathic Physicians
- Credential
- M.D.
- Sex
- Male
- Sole proprietor
- No
- License
- R3E76 (MO)
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
20 yrs in NPPES registry
- Profile completeness38% of score
100% of core fields populated
- Practice footprint23% of score
2 documented practice locations
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 · 2 distinct drugs on file.
| Drug | Part D claims (2024) |
|---|---|
| Atorvastatin Calcium | 13 |
| Simvastatin | 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
Additional practice locations (1)
- 9426 Phoenix Village PkwyO Fallon, MO 63368-4781Phone: (636) 561-5999Fax: (636) 561-4746
Registry dates
- Enumerated
- 2006-02-22
- Last updated
- 2021-02-24
- Certified
- 2021-02-24
Frequently asked questions
- What is John O'Brien's NPI number?
- John O'Brien's National Provider Identifier (NPI) is 1083689061, a unique 10-digit ID issued by CMS for use in standard healthcare transactions.
- What is John O'Brien's specialty?
- John O'Brien is listed in the NPPES registry with a primary specialty of Family Medicine Physician (Allopathic & Osteopathic Physicians).
- Where is John O'Brien located?
- John O'Brien's practice location on file with NPPES is 2630 Highway K, O Fallon, MO 63368-6624.
- What is John O'Brien's phone number?
- The practice phone number listed in the NPPES registry for John O'Brien is (636) 240-5454.
- Is John O'Brien's NPI active?
- Yes — John O'Brien's NPI (1083689061) is active in the NPPES registry as of the last update on 2021-02-24.
Source: CMS NPPES Data Dissemination (June 2026). NPI Central is not affiliated with CMS. Data is provided as-is from the public registry.