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Infectious Disease

Cassidy W. Claassen, MD

Works at hospitals in Baltimore, MD · Maryland

Summary

Dr. Cassidy W. Claassen, MD is an infectious disease doctor at 22 S Green St, Baltimore, MD 21201. Phone: (410) 328-8040. Accepts Medicare assignment. In 2024, Cassidy W. Claassen had 11 Original Medicare patients and 37 services. NPI 1477796696. 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: Infectious disease doctor (Medicare lists Infectious Disease)
  • Address: 22 S Green St, Baltimore, MD 21201 · Directions
  • Phone: (410) 328‑8040
  • Medicare: Accepts Medicare assignment
  • Hospital: University of Maryland Medical Center
  • Group practice: University of Maryland Physicians PA
  • Medical school: University Of Maryland School Of Medicine · graduated 2009 (17 years since medical school)
  • Gender (as listed): Male

From official Medicare data

This page shows what Medicare's official clinician data says about Cassidy W. Claassen, 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 Cassidy W. Claassen accept Medicare assignment?
Yes. Medicare's clinician data says Cassidy W. Claassen 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 Cassidy W. Claassen see?
In 2024, CMS data shows 11 Original Medicare patients and 37 services for Cassidy W. Claassen. This counts Original Medicare only and measures volume, not quality.
What is Cassidy W. Claassen's NPI number?
1477796696. 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 Cassidy W. Claassen, 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 patients11
Services billed to Medicare37
Different services or procedures9
Participating Medicare providerYes
Average age of these patients62

Hospitals where Cassidy W. Claassen works

Medicare's Facility Affiliation Data lists Cassidy W. Claassen 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.

Practice locations

Addresses where Cassidy W. Claassen is enrolled with Medicare (CMS data updated October 2, 2026).

Group practices

Medicare enrollment lists Cassidy W. Claassen as a member of this group (CMS data updated October 2, 2026).

  • University of Maryland Physicians PA404 clinicians in the group

Specialties

Find other Infectious Disease doctors in Maryland →

Other infectious disease doctors in Baltimore

Clinicians with the same Medicare primary specialty in Baltimore, MD — not a recommendation.

All infectious disease doctors in Baltimore →

Other clinicians in University of Maryland Physicians PA

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

Clinician information

CredentialMD
Medical schoolUniversity Of Maryland School Of Medicine
Graduation year2009 (17 years since medical school)
Gender (as listed)Male
Medicare assignmentAccepts (Medicare-approved amount as full payment)
NPI (National Provider Identifier)1477796696
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