MARK C O'BRIEN (D.O.) – Specialist, NPI 1497744247
Specialist
Main info
Doctor Profile
Profile Insights
NPPES metrics only — not quality of care.
21,508 INTERNAL MEDICINE in CA
Loading map...
Provider Addresses for MARK C O'BRIEN (D.O.)
3156, Vista Way, Oceanside, San Diego County, California, 92056, United States
SUITE 405
OCEANSIDE, CA 920563622
Phone: (760) 439-6581
Fax: (760) 769-6585
Type: Location
2604, El Camino Real, Palamai, Carlsbad, San Diego County, California, 92008, United States
SUITE 392
CARLSBAD, CA 920081205
Phone: (877) 286-8459
Fax: (760) 439-6581
Type: Mailing
161 THUNDER DR STE 210
VISTA, CA 920836052
Phone: (760) 216-6500
Fax: (760) 295-4753
Type: Mailing
NPPES updates history
No NPPES updates recorded for this provider.
Prescription Activity
Loading prescription activity...
Open Payments (CMS)
No Open Payments data available for this provider.
This can happen when there are no reportable CMS Open Payments records.
Medicare Enrollment & Revalidation
Source: CMS public data · Not endorsed by CMS ·
Educational use only—not medical, billing, or legal advice.
PECOS enrollment status
Participating (accepts Medicare assignment)
Enrollment effective: 2008-03-07
PECOS data refreshed: 2026-05-27
Medicare revalidation (CMS due date list)
Due date not assigned yet
CMS is tracking this Medicare enrollment for revalidation, but has not published a due date.
Enrollment records
1
Earliest due date
Not assigned (TBD)
CMS data updated
2026-06-01
Revalidation progress
- Medicare enrolled
- On CMS revalidation list
- Due date assigned
- Revalidate in PECOS
CMS enrollment records
| Enrollment ID | Type | Specialty | State | Due date |
|---|---|---|---|---|
| I20080307000443 | I | Internal Medicine | CA | TBD |
What to do next
- No action required while the due date shows TBD.
- Check the CMS Revalidation Lookup Tool periodically — CMS updates the list about every 60 days.
- Do not submit a revalidation application in PECOS until CMS publishes a concrete due date.
Prepare CMS-855 application → · Look up this NPI in PECOS → · Verify on CMS PECOS
Medicare Utilization (FFS)
Source: CMS public data · Not endorsed by CMS · Beneficiary counts under 11 are suppressed in source data ·
Educational use only—not medical, billing, or legal advice.
Top Medicare procedures (2023) · refreshed 2026-05-27
| HCPCS | Description | Services | Beneficiaries | Medicare allowed |
|---|---|---|---|---|
| 99233 | Subsequent hospital care with moderate levelof medical decision making, if using time, at least 50 minutes | 323 | 118 | $0 |
| 99239 | Hospital discharge day management, more than 30 minutes | 121 | 117 | $0 |
| 99232 | Subsequent hospital care with moderate levelof medical decision making, if using time, at least 35 minutes | 116 | 60 | $0 |
| 99223 | Initial hospital care with moderate level of medical decision making, if using time, at least 75 minutes | 77 | 76 | $0 |
Insurance plans in this area (ZIP 92056)
Loading plans...
Reviews
All reviews are moderated before publication. Reviews reflect users' opinions; we do not verify the accuracy of individual reviews.
No reviews yet. Be the first to share your experience — your opinion helps families compare providers.