Michael J. Duffy, PA
- Medicare patients, 2024
- 105
- Part D claims, 2024
- 708
- Industry payments
- $19
- Affiliated sites
- 2
- Medical groups
- 2
- Practice address
- 844 Old Tunnel Road, Grass Valley, CA 95945
- Practice phone
- Call (530) 273-4984
- Professional email
- Get professional email
- Personal email
- Get personal email
- Mobile number
- Get mobile number
Primary practice
Western Sierra Medical Clinic - Grass Valley (Old Tunnel Rd)
FQHC - Main Site · Grass Valley, California
Find Michael Duffy's professional email, personal email and mobile number
Dmand AI checks each channel through healthcare-specific waterfall enrichment. See what is on file with a free account, with practice phones, licenses and affiliations.
Michael J. Duffy is a physician assistant in Grass Valley, California
Michael Duffy practices at Western Sierra Medical Clinic - Grass Valley (Old Tunnel Rd) in Grass Valley, California.
Michael Duffy's NPI, 1801839188, was assigned on June 14, 2006. Michael Duffy holds California license PA11368.
- NPI
- 1801839188NPI Registry (opens in a new tab)
- NPI enumeration date
- June 14, 2006
- NPI status
- Active
- Practice phone
- (530) 273-4984
- Professional email
- Get email
- Personal email
- Get email
- Mobile number
- Get number
- Sex
- Male
- Estimated age
- 73
- Medical school graduation
- 1979
Sources: NPPES NPI Registry (CMS); Dmand AI Professional Profile Data; and Dmand AI Affiliation Data
Michael J. Duffy practices at Western Sierra Medical Clinic - Grass Valley (Old Tunnel Rd) in Grass Valley, California
Michael Duffy's primary practice is Western Sierra Medical Clinic - Grass Valley (Old Tunnel Rd), at 844 Old Tunnel Road, Grass Valley, CA 95945 in Nevada County. The practice phone is (530) 273-4984.
- Western Sierra Medical Clinic - Grass Valley (Old Tunnel Rd)844 Old Tunnel Road, Grass Valley, CA 95945 · Nevada CountyPhone(530) 273-4984
Source: Dmand AI Affiliation Data
Michael J. Duffy is affiliated with 2 sites of care and 2 medical groups
Michael Duffy's primary practice is Western Sierra Medical Clinic - Grass Valley (Old Tunnel Rd) in Grass Valley, California. The medical group on file is Western Sierra Medical Clinic. Dmand AI also links Michael Duffy to 1 more urgent care center and 1 medical group, each named with a free account. Michael Duffy's employer is on file too: a community health center (fqhc).
Sources: Dmand AI Affiliation Data; and Dmand AI Org Hierarchy Data
Dmand AI tracks the EHR system at Michael J. Duffy's practice
Dmand AI tracks the electronic health record (EHR) system at each site where Michael Duffy practices, 2 sites in all. Vendor and product names are available with a free account.
| Site | EHR vendor and product |
|---|---|
| Western Sierra Medical Clinic - Grass Valley (Old Tunnel Rd) | Available with a free account |
| +1 more site and 1 medical group | Available with a free account |
Source: Dmand AI Technology Install Data
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Michael J. Duffy is one of 11,482 physician assistants in California
Physician assistant is Michael Duffy's primary specialty in the NPI Registry, under taxonomy code 363A00000X. Michael Duffy is licensed in California.
Specialties and state licenses
- Physician assistant, CaliforniaPrimary
Physician assistants near Michael Duffy
Counts of physician assistants with a Dmand AI profile, by place and practice. Each opens the list.
Sources: NPPES NPI Registry (CMS); Dmand AI Professional Profile Data; and Dmand AI Peer Benchmarks
Michael J. Duffy treated 105 Medicare patients in 2024, average age 74
CMS counts 105 Medicare patients who saw Michael Duffy in 2024. The largest group is 65 to 74, with 50 patients. 72% of them have high cholesterol, and 64% have high blood pressure. 14% are also on Medicaid. Their average risk score is 1.03, where 1.00 is the Medicare average.
Across all payers, Dmand AI patient panel data puts Michael Duffy's median patient age at 36, with 66% women.
Michael Duffy's Medicare patients by age, 2024
CMS leaves out age groups with fewer than 11 patients.
Michael Duffy's Medicare patients by sex, 2024
- Women5956%
- Men4644%
Chronic conditions among Michael Duffy's Medicare patients, 2024
- High cholesterol72%
- High blood pressure64%
- Arthritis45%
- Mood disorders34%
- Depression29%
- Anxiety23%
- Ischemic heart disease19%
- Osteoporosis19%
Share of Medicare patients with each condition. A patient can have several.
Michael Duffy's patients across all payers
Dmand AI patient panel data covers Medicare, Medicaid and commercial patients.
Patient panel by age, all payers
Median age 36
Patient panel by sex, all payers
- Women66%
- Men33%
Sources: Dmand AI Patient Panel Data; and Medicare Physician & Other Practitioners - by Provider (CMS), 2024 data
Michael J. Duffy wrote 708 Medicare Part D claims in 2024
In 2024, Michael Duffy wrote 708 Medicare Part D claims for 386 patients. 86% of them were for generic drugs.
Michael Duffy's Part D claims by kind of drug, 2024
- Generic611 claims86%
- Brand-name86 claims12%
- Other11 claims2%
Drug classes CMS tracks in Michael Duffy's Part D claims, 2024
- Antibiotics28%200 of 708 claims
Share of all Part D claims for each drug class CMS reports on. Classes with no claims are left out.
Source: Medicare Part D Prescribers - by Provider (CMS), 2024 data
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Michael J. Duffy received $19 in industry payments in 2025
CMS Open Payments shows 1 general payment to Michael Duffy from 1 drug or device company in 2025. Food and beverage make up the largest share, 100% of the total. Mentor Worldwide LLC paid the most, $19.
Companies that paid Michael Duffy the most, 2025 to 2025
Share is of all general payments to this clinician.
Source: Open Payments (CMS), 2025 data, released July 7, 2026
Sources for Michael J. Duffy's profile data
| Data on this page | Source |
|---|---|
| NPI, name, sex, specialty and licenses | NPPES NPI Registry (CMS) (opens in a new tab)Dmand AI Professional Profile Data |
| Practice locations and phone | Dmand AI Affiliation Data |
| Primary practice, affiliations and health system | Dmand AI Affiliation DataDmand AI Org Hierarchy Data |
| Medicare patients and the all-payer patient panel | Dmand AI Patient Panel DataMedicare Physician & Other Practitioners - by Provider (CMS) (opens in a new tab) |
| Part D prescribing | Medicare Part D Prescribers - by Provider (CMS) (opens in a new tab) |
| Industry payments | Open Payments (CMS) (opens in a new tab) |
| EHR at each practice site | Dmand AI Technology Install Data |
| Similar physicians | Dmand AI Affiliation Data |
Data last refreshed October 2026Report an inaccuracyRemove my information
FAQ
Frequently asked questions about Michael J. Duffy
Spotted something out of date? Email hello@dmand.ai and we will check the record. Contact details live in the free trial.
What is Michael J. Duffy's NPI number?
Michael J. Duffy's NPI number is 1801839188. It was assigned on June 14, 2006, and it is active in the NPI Registry.
What does Michael J. Duffy specialize in?
Michael J. Duffy is a physician assistant in Grass Valley, California. The primary specialty in the NPI Registry is Physician Assistant (taxonomy code 363A00000X).
Where does Michael J. Duffy practice?
Michael Duffy practices at 844 Old Tunnel Road, Grass Valley, CA 95945. Michael Duffy's primary practice is Western Sierra Medical Clinic - Grass Valley (Old Tunnel Rd) in Grass Valley, California. Dmand AI also links Michael Duffy to 1 urgent care center and 1 medical group.
What is Michael J. Duffy's office phone number?
The practice phone on file for Michael Duffy is (530) 273-4984.
What is Michael J. Duffy's medical license number?
Michael Duffy holds California license PA11368.
What medical group is Michael J. Duffy part of?
Michael Duffy is linked to Western Sierra Medical Clinic. Dmand AI links Michael Duffy to 1 more medical group.
How many Medicare patients does Michael J. Duffy see?
CMS counts 105 Medicare patients who saw Michael Duffy in 2024, with an average age of 74.
Has Michael J. Duffy received payments from drug or device companies?
CMS Open Payments shows $19 in general payments to Michael Duffy from 1 company from 2025 to 2025. The largest total came from Mentor Worldwide LLC.
How long has Michael J. Duffy been practicing?
Michael Duffy graduated from medical school in 1979, 47 years ago.
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