Quick answers
- Does Karen Costenbader accept Medicare assignment?
- Yes. Medicare's clinician data says Karen Costenbader 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 Karen Costenbader see?
- In 2024, CMS data shows 56 Original Medicare patients and 91 services for Karen Costenbader. This counts Original Medicare only and measures volume, not quality.
- What is Karen Costenbader's NPI number?
- 1447216825. 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 Karen Costenbader, 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 | 56 |
|---|---|
| Services billed to Medicare | 91 |
| Different services or procedures | 12 |
| Participating Medicare provider | Yes |
| Average age of these patients | 71 |
Most frequent services
- Established patient office or other outpatient visit with moderate level of decision making, if using time, 30 minutes or more (99214)55 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 blood pressure73%
- High cholesterol73%
- Arthritis70%
- Osteoporosis46%
- Ischemic heart disease36%
- Chronic kidney disease34%
Hospitals where Karen Costenbader works
Medicare's Facility Affiliation Data lists Karen Costenbader 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.
- Brigham and Women's HospitalBoston, MA · Acute Care Hospital · Medicare rating: 5 of 5 stars · Emergency services: listed by Medicare · CCN 220110
- Massachusetts General HospitalBoston, MA · Acute Care Hospital · Medicare rating: 5 of 5 stars · Emergency services: listed by Medicare · CCN 220071
Practice locations
Addresses where Karen Costenbader is enrolled with Medicare (CMS data updated October 2, 2026).
- 45 Francis StBoston, MA 02115 (617) 732‑5500
Group practices
Medicare enrollment lists Karen Costenbader as a member of this group (CMS data updated October 2, 2026).
- Brigham and Womens Physicians Organization Inc2,994 clinicians in the group
Specialties
- Rheumatologyprimary
Other rheumatologists in Boston
Clinicians with the same Medicare primary specialty in Boston, MA — not a recommendation.
Other clinicians in Brigham and Womens Physicians Organization Inc
Medicare enrollment lists these clinicians in the same group practice — not a recommendation.
Clinician information
| Credential | MD |
|---|---|
| Medical school | Harvard Medical School |
| Graduation year | 1995 (31 years since medical school) |
| Gender (as listed) | Female |
| Medicare assignment | Accepts (Medicare-approved amount as full payment) |
| Telehealth | Offers telehealth services |
| NPI (National Provider Identifier) | 1447216825 |
| 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