Stephen Diefenderfer
NPI 1497488704 · Physician Assistant · Boston, MA
Enrolled with Medicare as Practitioner - Physician Assistant · source: CMS PECOS Public Provider Enrollment (2026.04.01)
Stephen Diefenderfer is a Physician Assistant provider in Boston, MA (NPI 1497488704).
Provider details
- NPI number
- 1497488704
- Entity type
- Individual
- Primary specialty
- Physician AssistantPhysician Assistants & Advanced Practice Nursing Providers
- Sex
- Male
- Sole proprietor
- No
Specialties & taxonomies
Physician Assistants & Advanced Practice Nursing Providers
Student, Health Care
Profile Score
A profile completeness & documented-activity index — NOT a quality, outcomes, or patient-satisfaction rating.
- Registry tenure28% of score
3 yrs in NPPES registry
- Profile completeness28% of score
83% of core fields populated
- Practice footprint17% of score
2 documented practice locations
- Medicare service volume (vs. specialty peers)28% of score
259 Medicare services, 2024 (ranked within specialty)
Medicare volume is ranked against active providers in the same specialty. Signals a provider has no public data for (e.g. Medicare claims) are left out of the score entirely — never counted as zero — so providers without that data are not penalized. See the full formula and weights in our methodology.
What this provider does (Medicare)
Based on Medicare fee-for-service claims, 2024; not all care is captured.
| Service (HCPCS) | Medicare services | Typical Medicare-allowed (2024) |
|---|---|---|
| Prolonged Hospital Inpatient Or Observation Care Evaluation and Management Service(s) Beyond the Total Time for the Primary Service (when the Primary Service Has Been Selected Using Time on the Date of the Primary Service); Each Additional 15 Minutes By ThG0316 | 170 | $27 |
| Subsequent Hospital Care With Moderate Levelof Medical Decision Making, If Using Time, at Least 50 Minutes99233 | 77 | $105 |
| Hospital Discharge Day Management, More Than 30 Minutes99239 | 12 | $103 |
Typical Medicare-allowed amounts for these services range $27–$105 (2024). The Medicare-allowed amount is what Medicare recognizes for a service under fee-for-service — a reference figure for 2024, not a price quote and not what you would be billed. Medicare Part B covers roughly an eighth of all NPIs (65+ skew); services with fewer than 11 beneficiaries are suppressed by CMS. Source: CMS Medicare Physician & Other Practitioners, by Provider & Service.
Practice location
Mailing address
Additional practice locations (1)
- 588 Longmeadow StLongmeadow, MA 01106-2212Phone: (413) 565-1000
Registry dates
- Enumerated
- 2022-07-05
- Last updated
- 2024-07-09
- Certified
- 2024-07-09
Frequently asked questions
- What is Stephen Diefenderfer's NPI number?
- Stephen Diefenderfer's National Provider Identifier (NPI) is 1497488704, a unique 10-digit ID issued by CMS for use in standard healthcare transactions.
- What is Stephen Diefenderfer's specialty?
- Stephen Diefenderfer is listed in the NPPES registry with a primary specialty of Physician Assistant (Physician Assistants & Advanced Practice Nursing Providers).
- Where is Stephen Diefenderfer located?
- Stephen Diefenderfer's practice location on file with NPPES is 55 Fruit St, Boston, MA 02114-2621.
- What is Stephen Diefenderfer's phone number?
- The practice phone number listed in the NPPES registry for Stephen Diefenderfer is (617) 726-2000.
- Does Stephen Diefenderfer accept Medicare?
- Stephen Diefenderfer is approved to bill Medicare according to CMS PECOS enrollment data (2026.04.01). Confirm current participation with the provider before scheduling.
- Is Stephen Diefenderfer's NPI active?
- Yes — Stephen Diefenderfer's NPI (1497488704) is active in the NPPES registry as of the last update on 2024-07-09.
Source: CMS NPPES Data Dissemination (June 2026). NPI Central is not affiliated with CMS. Data is provided as-is from the public registry.