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Nephrology

Anne D. Sebastian, MD

Works at hospitals in Greenwich, CT · Stamford, CT · Connecticut

Summary

Dr. Anne D. Sebastian, MD is a nephrologist at 292 Long Ridge Rd, Suite 203, Stamford, CT 06902. Phone: (203) 276-2435. Accepts Medicare assignment. In 2024, Anne D. Sebastian had 223 Original Medicare patients and 2,608 services. NPI 1699180042. Source: CMS National Downloadable File, updated October 2, 2026; CMS Facility Affiliation Data, updated October 2, 2026; CMS Medicare Physician & Other Practitioners, data year 2024.

  • Specialty: Nephrologist (Medicare lists Nephrology)
  • Address: 292 Long Ridge Rd, Suite 203, Stamford, CT 06902 · Directions
  • Phone: (203) 276‑2435
  • Medicare: Accepts Medicare assignment
  • Hospitals: Greenwich Hospital Association -, Stamford Hospital
  • Group practice: Stamford Health Medical Group Inc
  • Medical school: Albany Medical College Of Union University · graduated 2014 (12 years since medical school)
  • Gender (as listed): Female

From official Medicare data

This page shows what Medicare's official clinician data says about Anne D. Sebastian, joined by NPI number (data updated October 2, 2026). It is not a recommendation or a rating. Call the office or hospital to confirm before you go.

In a medical emergency, call 911.

Quick answers

Does Anne D. Sebastian accept Medicare assignment?
Yes. Medicare's clinician data says Anne D. Sebastian 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 Anne D. Sebastian see?
In 2024, CMS data shows 223 Original Medicare patients and 2,608 services for Anne D. Sebastian. This counts Original Medicare only and measures volume, not quality.
What is Anne D. Sebastian's NPI number?
1699180042. 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 Anne D. Sebastian, 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 patients223
Services billed to Medicare2,608
Different services or procedures29
Participating Medicare providerYes
Average age of these patients77

Most frequent services

  1. Subsequent hospital care with moderate levelof medical decision making, if using time, at least 35 minutes (99232)237 services
  2. 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)185 services
  3. Established patient office or other outpatient visit with moderate level of decision making, if using time, 30 minutes or more (99214)136 services
  4. Established patient office or other outpatient visit with high level of medical decision making, if using time, 40 minutes or more (99215)77 services
  5. Dialysis services, 4 or more physician visits per month (20 years or older) (90960)76 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 pressure75%
  • High cholesterol75%
  • Chronic kidney disease75%
  • Ischemic heart disease58%
  • Heart failure52%
  • Diabetes51%

Hospitals where Anne D. Sebastian works

Medicare's Facility Affiliation Data lists Anne D. Sebastian 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.

  • Greenwich Hospital Association -Greenwich, CT · Acute Care Hospital · Medicare rating: 5 of 5 stars · Emergency services: listed by Medicare · CCN 070018
  • Stamford HospitalStamford, CT · Acute Care Hospital · Medicare rating: 5 of 5 stars · Emergency services: listed by Medicare · CCN 070006

Practice locations

Addresses where Anne D. Sebastian is enrolled with Medicare (CMS data updated October 2, 2026).

Group practices

Medicare enrollment lists Anne D. Sebastian as a member of this group (CMS data updated October 2, 2026).

  • Stamford Health Medical Group Inc444 clinicians in the group

Specialties

Find other Nephrology doctors in Connecticut →

Other nephrologists in Stamford

Clinicians with the same Medicare primary specialty in Stamford, CT — not a recommendation.

All nephrologists in Stamford →

Other clinicians in Stamford Health Medical Group Inc

Medicare enrollment lists these clinicians in the same group practice — not a recommendation.

Clinician information

CredentialMD
Medical schoolAlbany Medical College Of Union University
Graduation year2014 (12 years since medical school)
Gender (as listed)Female
Medicare assignmentAccepts (Medicare-approved amount as full payment)
NPI (National Provider Identifier)1699180042
CorrectionsReport 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

  1. Facility Affiliation Data — Centers for Medicare & Medicaid Services (CMS), data updated October 2, 2026, retrieved October 29, 2026
  2. Hospital General Information — CMS, data updated October 26, 2026, retrieved November 13, 2026
  3. National Downloadable File (Doctors and Clinicians) — CMS, data updated October 2, 2026, retrieved October 29, 2026
  4. Medicare Physician & Other Practitioners - by Provider — CMS, data year 2024, released May 21, 2026; Medicare Physician & Other Practitioners - by Provider and Service
  5. NPI Registry — U.S. Department of Health and Human Services (NPPES), the clinician’s official record
  6. Medicare Care Compare — official Medicare tool to look up clinicians