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Recently Updated NPI Information — some details in this NPI profile have been updated in the NPI registry within the last 60 days.

CONNOR JAMES O'BRIEN MD
NPI 1457055964
Hospitalist in Orange, CA

Active since March 28, 2023
101 THE CITY DR S STE 400, ORANGE, CA 92868(714) 456-5691 Get Directions Write a Review

NPPES record last updated: September 9, 2026. Verified against the NPPES registry weekly; last sync: September 20, 2026.

Record update history: Sep 9, 2026, Mar 28, 2023 (2 updates tracked since 2023).

About Connor James O'brien Md NPPES

Official registry information on file with the National Plan and Provider Enumeration System.

CONNOR JAMES O'BRIEN MD (NPI 1457055964) is an individual hospitalist provider in Orange, California, licensed in California (A198979) and active in the NPI registry since March 2023. He maintains a secondary practice location in Petaluma.

NPPES Registry Identity

NPI1457055964
Entity TypeIndividualMale
Primary Taxonomy208M00000X
Provider Legal NameCONNOR JAMES O'BRIENCredential: MD
Location Address101 THE CITY DR S STE 400Orange, CA 92868-3201
Mailing Address104 PreserveIrvine, CA 92618-4804
Phone(714) 456-5691
Sole ProprietorYes
Enumeration DateMarch 28, 2023
Last NPPES UpdateSeptember 9, 20262 updates tracked since enumeration
NPPES CertifiedSeptember 9, 2026
✔ NPI 1457055964 is a valid, active identifier and passes the ISO check-digit test.

Specialties & Licenses

★ Primary SpecialtyHospitalistAllopathic & Osteopathic Physicians
Taxonomy Code208M00000X
License✔ Licensed in CA · A198979
Definition
Hospitalists are physicians whose primary professional focus is the general medical care of hospitalized patients. Their activities include patient care, teaching, research, and leadership related to Hospital Medicine. The term 'hospitalist' refers to physicians whose practice emphasizes providing care for hospitalized patients.
101 THE CITY DR S STE 400, Orange, CA 92868
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Secondary Practice Location 1

Location 1400 N McDowell BlvdPetaluma, CA 94954-2339 · Phone (707) 303-1709 · Fax (707) 303-3912

Other Providers at the Same Location NPPES 20

Providers registered at the same practice address, or within the immediate area, according to the NPPES registry.

BRIAN DIEP MD
Student in an Organized Health Care Education/Training Program
101 THE CITY DR S STE 400
ORANGE, CA 92868
Orange County (714) 456-5691
ANISH SAI KOLAN
Student in an Organized Health Care Education/Training Program
101 THE CITY DR S STE 400
ORANGE, CA 92868
Orange County (714) 456-5691
MICHELLE T NGUYEN
Student in an Organized Health Care Education/Training Program
101 THE CITY DR S STE 400
ORANGE, CA 92868
Orange County (714) 456-5691
DR. JOSEPH CARTON MD
Student in an Organized Health Care Education/Training Program
101 THE CITY DR S STE 400
ORANGE, CA 92868
Orange County (714) 456-5691
ERICA SHIN
Student in an Organized Health Care Education/Training Program
101 THE CITY DR S STE 400
ORANGE, CA 92868
Orange County (714) 456-5691
TIMOTHY CHANG
Student in an Organized Health Care Education/Training Program
101 THE CITY DR S STE 400
ORANGE, CA 92868
Orange County (714) 456-5691
SHANT ABRHAMIAN
Student in an Organized Health Care Education/Training Program
101 THE CITY DR S STE 400
ORANGE, CA 92868
Orange County (714) 456-5691
MICHELLE M NGUYEN
Psychiatry & Neurology (Neurology)
101 THE CITY DR S STE 400
ORANGE, CA 92868
Orange County (714) 456-5691

Frequently Asked Questions NPPES & CMS

Common questions about this NPI record, answered from the official NPPES registry and CMS datasets shown on this page.

What is Connor O'brien's NPI number?

The NPI number for Connor O'brien is 1457055964. It was assigned to this individual provider in the NPPES registry on March 28, 2023.

Where is Connor O'brien located?

Connor O'brien practices at 101 The City Dr S Ste 400, Orange, CA 92868. The listed phone number is (714) 456-5691.

What is Connor O'brien's specialty?

The primary specialty registered for this NPI is Hospitalist with taxonomy code 208M00000X.

When was this NPI record last updated?

The NPPES record for Connor O'brien was last updated on September 9, 2026. NPI Profile syncs weekly with the NPPES registry data releases published by CMS. This NPI record was last updated 13 days ago. If this record has changed at CMS more recently, you can request an on-demand re-check against the live CMS registry, directly from this page.