Provider records sourced from NPPES (CMS National Plan & Provider Enumeration System). Data current as of October 4, 2026.
NPIDirectory

Mark Brennan, DO

Individual provider Surgery Physician · NPI 1174523443

Mark Brennan, DO practises Vascular Surgery in Johnson City, New York. Graduated from Philadelphia College of Osteopathic Medicine in 1994, 32 years ago. Practices with United Health Services Hospitals, Inc, a 472-clinician group and accepts Medicare assignment. Licensed in New York.

Years since qualifying
32
Trained at
Philadelphia College of Osteopathic Medicine
Licensed in
NY
In the registry since
2005
Specialties on file
2
What do these letters mean?
DO — Doctor of Osteopathic Medicine
A fully licensed physician, trained like an MD with additional musculoskeletal training. Equivalent practice rights in all 50 states.

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Practice location Address checks out

30 Harrison St Ste 455
Johnson City, NY 13790-2161 Not confirmed with CMS for 12 years — call before visiting
Phone: (607) 763-8100
Fax: (607) 763-8048
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Pin is approximate — placed at the ZIP-code centre, not the exact door.

Specialties & licences

Vascular Surgery Physician (primary) Taxonomy 2086S0129X · Licence 217717 (NY)
Surgery Physician Taxonomy 208600000X · Licence 217717 (NY)

Record details

NPI number1174523443
Entity typeIndividual (Type 1)
GenderMale
Credentials DO
Sole proprietorNo
NPI enumeratedJuly 28, 2005
Last updated in NPPESSeptember 15, 2014

Medicare enrollment

From the CMS Doctors & Clinicians file — this clinician is enrolled in Medicare.

Medicare specialtyVASCULAR SURGERY
Medical schoolPHILADELPHIA COLLEGE OF OSTEOPATHIC MEDICINE
Graduated 1994 (32 years in practice)
Group practice United Health Services Hospitals, Inc. — 472 clinicians
Accepts Medicare assignment Yes — accepts the Medicare-approved amount
Practice locations5 on file with Medicare

Procedures

From CMS Care Compare, which counts the procedures a clinician billed to Original Medicare and Medicare Advantage over a recent 12-month period. CMS reports a fixed list of common procedures, so this is not everything the clinician does. Counts of 10 or fewer are given as a range, because CMS withholds small numbers.

Leg revascularization (restoring blood flow) 20 times · 73rd percentile
Hernia repair - groin (open) 1–10 times
Upper gastrointestinal (GI) endoscopy for acid reflux 1–10 times
Varicose vein removal 1–10 times

The percentile compares how often this clinician performed the procedure with other clinicians who performed it, as CMS calculates it. It measures volume, not outcomes or skill.

Medicare patients and services, 2024

From the CMS Medicare Physician & Other Practitioners file for calendar year 2024. It counts Original Medicare patients only, so a practice that mostly sees Medicare Advantage or privately insured patients looks smaller here than it is.

Medicare patients123
Services billed 340 a service is one billed item, such as a visit, a test or a procedure
Average patient age73

Dollar amounts are not shown. What Medicare pays a practice is gross billings, before staff, premises and tax and including the cost of any drugs it administers, so it is not what a clinician earns.

Payments from drug and device companies, 2025

Drug and device makers are required by federal law (the Physician Payments Sunshine Act) to report what they pay or give to clinicians, and CMS publishes the reports as Open Payments. This is the 2025 program year. A report is a record of a payment, not an allegation of anything, and many are small items such as meals. Only general payments are listed here; research payments and ownership or investment interests are reported separately by CMS and are not shown.

Food and Beverage $1,903 34 payments · a meal or drink at a meeting or visit, not a fee

Each amount is the sum of what companies reported for that kind of payment in 2025, rounded to the dollar. Not all of it is income to the clinician: a meal is not a fee, a charitable contribution goes to a charity, and a royalty or an acquisition payment is not a salary.

Check a report, or dispute one, at the source in CMS’s own tool, Open Payments. Corrections go through CMS’s dispute process. This site removes a home address on request and asks for no proof, because that is privacy; it will not remove an accurate payment report on request, because that is a statutory public disclosure.

Practises at

Facilities the CMS Facility Affiliation file lists for this clinician.

Colleagues at United Health Services Hospitals, Inc

Clinicians the CMS Doctors & Clinicians file lists under the same group practice. CMS counts 472 clinicians in the practice; 12 are shown here.

Other providers in Johnson City