Quick answers
- Does Holly Mazur accept Medicare assignment?
- Yes. Medicare's clinician data says Holly Mazur accepts Medicare assignment (the Medicare-approved amount as full payment for covered services), as of October 2, 2026. Ask the office to confirm before your visit.
- How many Medicare patients does Holly Mazur see?
- In 2024, CMS data shows 271 Original Medicare patients and 1,767 services for Holly Mazur. This counts Original Medicare only and measures volume, not quality.
- What is Holly Mazur's NPI number?
- 1295780617. The NPI (National Provider Identifier) is the clinician's permanent federal ID; you can look it up in the official NPI Registry.
Medicare activity in 2024
Official CMS public-use data for Holly Mazur, data year 2024 (released May 21, 2026). It covers Original Medicare (fee-for-service) patients only, not Medicare Advantage or other insurance. It shows volume, not quality or outcomes. CMS hides any count of 10 or fewer patients.
| Original Medicare patients | 271 |
|---|---|
| Services billed to Medicare | 1,767 |
| Different services or procedures | 103 |
| Participating Medicare provider | Yes |
| Average age of these patients | 75 |
Most frequent services
- Established patient office or other outpatient visit with moderate level of decision making, if using time, 30 minutes or more (99214)208 services
- Insertion of needle into vein for collection of blood sample (36415)186 services
- Complete blood cell count (red cells, white blood cell, platelets), automated test and automated differential white blood cell count (85025)102 services
- Blood test, thyroid stimulating hormone (tsh) (84443)88 services
- Visit complexity inherent to evaluation and management associated with medical care services that serve as the continuing focal point for all needed health care services and/or with medical care services that are part of ongoing care related to a patient's (G2211)84 services
Chronic conditions among these patients
Share of this clinician’s Original Medicare patients with each condition, as published by CMS (it describes the patients, not the care given).
- High cholesterol75%
- High blood pressure69%
- Arthritis40%
- Anxiety30%
- Chronic kidney disease26%
- Diabetes22%
Hospitals where Holly Mazur works
Medicare's Facility Affiliation Data lists Holly Mazur at these hospitals (updated October 2, 2026). Each hospital page shows its address, phone, emergency services, Medicare rating and all its clinicians. Star rating and emergency services: Hospital General Information (CMS), data updated October 26, 2026.
- Emerson Hospital -W Concord, MA · Acute Care Hospital · Medicare rating: 5 of 5 stars · Emergency services: listed by Medicare · CCN 220084
- UMass Memorial Healthalliance HospitalsLeominster, MA · Acute Care Hospital · Medicare rating: 3 of 5 stars · Emergency services: listed by Medicare · CCN 220001
- UMass Memorial Medical Center/University CampusWorcester, MA · Acute Care Hospital · Medicare rating: 3 of 5 stars · Emergency services: listed by Medicare · CCN 220163
Practice locations
Addresses where Holly Mazur is enrolled with Medicare (CMS data updated October 2, 2026).
- 87 N Main StLeominster, MA 01453
Specialties
- Internal Medicineprimary
Other internal medicine doctors in Leominster
Clinicians with the same Medicare primary specialty in Leominster, MA — not a recommendation.
Clinician information
| Credential | MD |
|---|---|
| Medical school | Tufts University School Of Medicine |
| Graduation year | 1992 (34 years since medical school) |
| Gender (as listed) | Female |
| Medicare assignment | Accepts (Medicare-approved amount as full payment) |
| NPI (National Provider Identifier) | 1295780617 |
| Corrections | Report an error or suggest an update → |
Most corrections must be made at the source: clinicians update their NPI Registry record (NPPES) and their Medicare enrollment (PECOS); this page follows the next data release.
Sources
- Facility Affiliation Data — Centers for Medicare & Medicaid Services (CMS), data updated October 2, 2026, retrieved October 29, 2026
- Hospital General Information — CMS, data updated October 26, 2026, retrieved November 13, 2026
- National Downloadable File (Doctors and Clinicians) — CMS, data updated October 2, 2026, retrieved October 29, 2026
- Medicare Physician & Other Practitioners - by Provider — CMS, data year 2024, released May 21, 2026; Medicare Physician & Other Practitioners - by Provider and Service
- NPI Registry — U.S. Department of Health and Human Services (NPPES), the clinician’s official record
- Medicare Care Compare — official Medicare tool to look up clinicians