Quick answers
- Which hospitals does John Warren work at?
- Medicare's official clinician data lists John Warren at 1 hospital: Baystate Franklin Medical Center. This is where the clinician works or has privileges; call the hospital to confirm.
- Where does John Warren see patients?
- Medicare's clinician data lists 2 practice locations, including West Springfield, MA and Greenfield, MA. Call before your visit to confirm the address.
- What is John Warren's specialty?
- Medicare lists Ophthalmology as the primary specialty.
- Does John Warren accept Medicare assignment?
- Yes. Medicare's clinician data says John Warren accepts Medicare assignment (the Medicare-approved amount as full payment for covered services), as of 2026-10-02. Ask the office to confirm before your visit.
- What is the phone number for John Warren?
- (413) 452-4111, as listed in official Medicare / NPI Registry data.
- What is John Warren's NPI number?
- 1386634400. The NPI (National Provider Identifier) is the clinician's permanent federal ID; you can look it up in the official NPI Registry.
Hospitals where John Warren works
Medicare's Facility Affiliation Data lists John Warren at these hospitals (updated 2026-10-02). Each hospital page shows its address, phone, emergency services, Medicare rating and all its clinicians.
- Baystate Franklin Medical CenterGreenfield, MA · Acute Care Hospital · CCN 220016
Practice locations
Addresses where John Warren is enrolled with Medicare (CMS data updated 2026-10-02).
- 180 Daggett DrWest Springfield, MA 01089 (413) 452‑4111
- 33 Riddell St, Suite 2Greenfield, MA 01301 (413) 774‑7016
Group practices
Medicare enrollment lists John Warren as a member of this group (CMS data updated 2026-10-02).
- Longwood Eye LLC16 clinicians in the group
Specialties
- Ophthalmologyprimary
Other ophthalmologists in West Springfield
Clinicians with the same Medicare primary specialty in West Springfield, MA — not a recommendation.
Clinician information
| Credential | MD |
|---|---|
| Medical school | Stanford University School Of Medicine |
| Graduation year | 1997 |
| Gender (as listed) | Male |
| Medicare assignment | Accepts (Medicare-approved amount as full payment) |
| NPI (National Provider Identifier) | 1386634400 |
| 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 2026-10-02, retrieved 2026-10-29
- National Downloadable File (Doctors and Clinicians) — CMS, data updated 2026-10-02, retrieved 2026-10-29
- 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