Physician Profile
Unclaimed ProfileAbout O'BRIEN
Based in Vista, CA, Mark C O'Brien, D.O. is listed in the NPI registry under internal medicine. Mark graduated from Michigan State University College of Osteopathic Medicine in 1987.
Summarised automatically from public NPI registry and CMS Medicare data. Not written or reviewed by this provider. Claim this profile to replace it.
Education & Training
Areas of Expertise
Common questions
What does Dr. O'Brien specialise in?
Dr. O'Brien is an internal medicine in Vista, CA. This is the primary taxonomy recorded against the NPI in the federal registry, listed there as “INTERNAL MEDICINE”.
NPI registry
Where is Dr. O'Brien located?
Dr. O'Brien is listed at 161 THUNDER DR STE 210, Vista, CA 92083. Addresses come from the NPI registry and can lag a move, so confirm before travelling.
NPI registry
What is Dr. O'Brien's phone number?
The number on file is (760) 216-6500. Guide.md cannot book appointments or pass on messages — please call the office directly.
NPI registry
What is the NPI for Dr. O'Brien?
Dr. O'Brien's National Provider Identifier is 1497744247. It is issued by the Centers for Medicare & Medicaid Services and is unique and permanent — it does not change if they move practice.
NPI registry
Where did Dr. O'Brien go to medical school?
Dr. O'Brien attended Michigan State University College of Osteopathic Medicine, graduating in 1987. This comes from the CMS National Downloadable File.
CMS public data
How much experience does Dr. O'Brien have?
Dr. O'Brien has 39 years experience. Calculated from a graduation year of 1987, reported in the CMS National Downloadable File.
CMS public data
What does Dr. O'Brien do most often?
According to Medicare billing data, Dr. O'Brien the Medicare record under this individual NPI shows mainly office visits and diagnostic testing. Hospital-based physicians usually have their procedural work billed by the facility rather than under their own number, so this is a floor on their practice, not a description of it. This reflects Medicare patients only and is billing volume, not a measure of quality.
Medicare claims
Is Dr. O'Brien's profile verified?
Not yet. This profile is built from public federal data and has not been confirmed by Dr. O'Brien. If this is you, claiming it is free.
Guide.md
Licensing & Certification
Source: NPPES NPI Registry
Contact Information
- (760) 216-6500
- Email not available
Practice Locations
161 THUNDER DR STE 210
Vista, CA 92083
Procedures Most Often Billed to Medicare
657 services · 374 patients · 4 distinct codes
| Procedure | Type | Code | Services |
|---|---|---|---|
| Subsequent hospital care with moderate levelof medical decision making, if using time, at least 35 minutes | Office visit | 99232 |
276 |
| Subsequent hospital care with moderate levelof medical decision making, if using time, at least 50 minutes | Office visit | 99233 |
183 |
| Initial hospital care with moderate level of medical decision making, if using time, at least 75 minutes | Office visit | 99223 |
107 |
| Hospital discharge day management, more than 30 minutes | Office visit | 99239 |
91 |
Source: CMS Medicare public data. Shows how often procedures were billed — not quality of care or patient satisfaction.
Related providers
Connections drawn from the registry and from what providers have told us. A link here is not a referral or an endorsement.
Other internal medicines at this location 1
Same specialty, same street address — most likely the same department or group.
Related specialists at this location 4
Clinically related specialties at the same address — the people this provider most likely works alongside.
Also at this address 4
Providers at the same street address. Each files their own registry entry, so a shared practice often appears under several different names.
More connections — 24 related providers in 3 groups
Other internal medicines in Vista 8
Same specialty, same city.
Trained at Michigan State University College of Osteopathic Medicine 8
Other providers in the same specialty who trained at the same institution.
Class of 1987 at Michigan State University College of Osteopathic Medicine 8
Providers who graduated from the same medical school in the same year.
Provider data sourced from the NPPES NPI Registry and CMS public datasets. Information is provided for reference and is not medical advice.