$525 in research paymentsALXN1007 10 mg/kg once weeklyALXN1007 20 mg/kg once weeklyALXN1007 20 mg/kg twice weekly
Dr. Jonathan Kay, MD
NPI1699766964PAC ID0749253474
- Medicare services, 2024
- 273
- Medicare patients, 2024
- 127
- Part D claims, 2024
- 849
- Clinical trials
- 1
- MIPS score, 2024
- 100
- Practice address
- 55 North Ave, Mendon, MA 01756
- Practice phone
- Call (508) 334-1000
- Professional email
- Get professional email
- Personal email
- Get personal email
- Mobile number
- Get mobile number
Primary practice
Umass Memorial Medical Center
Mendon, Massachusetts
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Dr. Jonathan Kay is a rheumatologist in Mendon, Massachusetts
Dr. Kay practices at Umass Memorial Medical Center in Mendon, Massachusetts.
Dr. Kay's NPI, 1699766964, was assigned on November 4, 2005. Dr. Kay graduated from University of California, San Francisco School of Medicine in 1983. Dr. Kay holds Massachusetts license 55522.
NPI and contact details
- NPI
- 1699766964NPI Registry (opens in a new tab)
- Medicare PAC ID
- 0749253474
- NPI enumeration date
- November 4, 2005
- NPI status
- Active
- Accepts Medicare assignment
- Yes
- Practice phone
- (508) 334-1000
- Professional email
- Get email
- Personal email
- Get email
- Mobile number
- Get number
- Sex
- Male
- Estimated age
- 69
- Medical school graduation
- 1983
Sources: NPPES NPI Registry (CMS); Dmand AI Professional Profile Data; Dmand AI Practice Data; and Doctors and Clinicians National Downloadable File (CMS)
Dr. Jonathan Kay practices at Umass Memorial Medical Center in Mendon, Massachusetts
Dr. Kay's primary practice is Umass Memorial Medical Center, at 55 North Ave, Mendon, MA 01756 in Worcester County. The practice phone is (508) 334-1000.
- Umass Memorial Medical Center55 North Ave, Mendon, MA 01756 · Worcester CountyPhone(508) 334-1000
Sources: NPPES NPI Registry (CMS); and Dmand AI Practice Data
Dr. Jonathan Kay is affiliated with 5 sites of care and 1 medical group
Dr. Kay's primary practice is Umass Memorial Medical Center in Mendon, Massachusetts. Dr. Kay is also affiliated with UMass Memorial Medical Center - University Campus. The medical group on file is UMass Memorial Medical Group. Dmand AI also links Dr. Kay to 2 more hospitals and 1 group practice or clinic, each named with a free account.
Umass Memorial Medical CenterPrimary
Sources: NPPES NPI Registry (CMS); Dmand AI Practice Data; and Dmand AI Affiliation Data
Dmand AI tracks the EHR system at Dr. Jonathan Kay's practice
Dmand AI tracks the electronic health record (EHR) system at each site where Dr. Kay practices, 4 sites in all. Vendor and product names are available with a free account.
| Site | EHR vendor and product |
|---|---|
| Umass Memorial Medical Center | Available with a free account |
| +4 more affiliated sites | Available with a free account |
Source: Dmand AI Technology Install Data
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Dr. Jonathan Kay is one of 275 rheumatologists in Massachusetts
Rheumatology is Dr. Kay's primary specialty in the NPI Registry, under taxonomy code 207RR0500X. Dr. Kay is licensed in Massachusetts.
Specialties and state licenses
- Rheumatology, MassachusettsPrimary
Rheumatologists near Dr. Kay
Counts of rheumatologists 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
Dr. Jonathan Kay billed Medicare for 273 services in 2024
CMS data shows 273 Medicare services from Dr. Kay across 5 procedure codes in 2024, for 127 Medicare patients. Medicare paid $17,117 for them. Every service was in an office.
Medicare services, 2024273
Medicare patients127
Paid by Medicare$17,117
Procedure codes5
Dr. Kay's Medicare services by type, 2023 to 2024
- 2023
- 2024
- Office and hospital visits
- 2023: 2562024: 21217%
- Surgery
- 2023: 502024: 6122%
Dr. Kay compared with the Massachusetts median for rheumatologists, 2024
- Dr. Kay
- Massachusetts median
- Medicare services
- 273vs 41234% below
- Medicare patients
- 127vs 20939% below
- Part D claims
- 770vs 50552% above
Medians across 268 rheumatologists in Massachusetts with Dmand AI profiles that report each measure.
Dr. Kay's most billed Medicare procedure codes, 2024
CMS publishes codes billed for 11 or more Medicare patients. Each label is the code family; CPT descriptions are licensed by the AMA.
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Sources: Medicare Physician & Other Practitioners - by Provider and Service (CMS), 2024 data; and Dmand AI Peer Benchmarks
Dr. Jonathan Kay treated 127 Medicare patients in 2024, average age 72
CMS counts 127 Medicare patients who saw Dr. Kay in 2024. The largest group is 65 to 74, with 59 patients. 75% of them have arthritis, and 74% have high cholesterol. 20% are also on Medicaid. Their average risk score is 1.39, where 1.00 is the Medicare average.
Across all payers, Dmand AI patient panel data puts Dr. Kay's median patient age at 74, with 57% women.
Medicare patients, 2024127
Average age72
Average risk score1.39
Also on Medicaid20%
Dr. Kay's Medicare patients by age, 2024
CMS leaves out age groups with fewer than 11 patients.
Dr. Kay's Medicare patients by sex, 2024
- Women6047%
- Men6753%
Chronic conditions among Dr. Kay's Medicare patients, 2024
- Arthritis75%
- High cholesterol74%
- High blood pressure72%
- Diabetes31%
- Mood disorders27%
- Chronic kidney disease26%
- Ischemic heart disease25%
- Depression24%
Share of Medicare patients with each condition. A patient can have several.
Dr. Kay's patients across all payers
Dmand AI patient panel data covers Medicare, Medicaid and commercial patients.
Patient panel by age, all payers
Median age 74
Patient panel by sex, all payers
- Women57%
- Men43%
Sources: Dmand AI Patient Panel Data; and Medicare Physician & Other Practitioners - by Provider (CMS), 2024 data
Dr. Jonathan Kay wrote 849 Medicare Part D claims in 2024
In 2024, Dr. Kay wrote 849 Medicare Part D claims for 133 patients. 68% of them were for generic drugs. CMS names the drug for 770 of them, across 21 drugs with 11 or more claims each, at $1,593,603 in total drug cost. In 2023, CMS named 731 claims across 18 drugs.
Part D claims, 2024849
Drugs named by CMS21
Total drug cost$1.6M
Part D patients133
Dr. Kay's Part D claims by kind of drug, 2024
- Generic578 claims68%
- Brand-name271 claims32%
Dr. Kay's most prescribed drugs by claims, 2024
CMS names a drug when it has 11 or more claims. Share is of the claims for drugs CMS names.
Part D claims for drugs CMS names, 2023 to 2024
- 2023
- 2024
- Claims for drugs CMS names
- 2023: 7312024: 7705%
Drugs named by CMS: 21 in 2024, 18 in 2023.
Sources: Medicare Part D Prescribers - by Provider and Drug (CMS), 2024 data, released May 6, 2026; and Medicare Part D Prescribers - by Provider (CMS), 2024 data
Dr. Jonathan Kay scored 100 out of 100 in Medicare's MIPS program for 2024
CMS publishes a Merit-based Incentive Payment System (MIPS) score of 100 out of 100 for Dr. Kay for performance year 2024, reported through an alternative payment model (APM). Dr. Kay accepts Medicare assignment, so Medicare's approved amount is taken as full payment.
- Accepts Medicare assignment
- Yes
Dr. Kay's MIPS scores, performance year 2024
- 100of 100Final score
- 83of 100Quality
- 100of 100Promoting Interoperability
- 40of 100Improvement Activities
Each score is out of 100. The final score weighs the categories CMS scored for this clinician.
Sources: Doctors and Clinicians National Downloadable File (CMS); and Clinician Public Reporting: Overall MIPS Performance (CMS), 2024 data, released September 10, 2026
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Dr. Jonathan Kay has worked on 1 clinical trial
Dmand AI links Dr. Kay to 1 clinical trial. Open Payments lists research payments to Dr. Kay that name 1 trial.
Investigators on the most trials with Dr. Kay
- Nelson Jen An Chao, MD1 shared trial
- Jerrold J. Ellner, MD1 shared trial
- Francisco Marty, MD1 shared trial
Recent clinical trials with Dr. Kay
Sources: Open Payments (CMS), 2025 data, released July 7, 2026; ClinicalTrials.gov (National Library of Medicine); and Dmand AI Research Linkage
Dr. Jonathan Kay received $479,013 in industry payments from 2016 to 2025
CMS Open Payments shows 418 general payments to Dr. Kay from 28 drug and device companies from 2016 to 2025. Consulting fees make up the largest share, 70% of the total. Sandoz Inc. paid the most, $81,642. It also lists 8 research payments totaling $12,461 from 2016 to 2024, naming 1 clinical trial.
General payments to Dr. Kay by program year, 2016 to 2025
General payments to Dr. Kay by kind, 2016 to 2025
$479Kin total
- Consulting fees$332,76170%
- Travel and lodging$61,36613%
- Honoraria$43,0909%
- Speaker and faculty fees$29,3386%
- Other$12,1903%
Companies that paid Dr. Kay the most, 2016 to 2025
Share is of all general payments to this clinician.
Source: Open Payments (CMS), 2025 data, released July 7, 2026
Dr. Jonathan Kay graduated from University of California, San Francisco School of Medicine
Dr. Kay graduated from University of California, San Francisco School of Medicine in 1983.
- Medical school
Source: Dmand AI Professional Profile Data
Sources for Dr. Jonathan Kay'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 | NPPES NPI Registry (CMS) (opens in a new tab)Dmand AI Practice Data |
| Primary practice, affiliations and health system | NPPES NPI Registry (CMS) (opens in a new tab)Dmand AI Practice DataDmand AI Affiliation Data |
| Medicare services and procedure codes | Medicare Physician & Other Practitioners - by Provider and Service (CMS) (opens in a new tab) |
| State medians for the same specialty | Dmand AI Peer Benchmarks |
| 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 and Drug (CMS) (opens in a new tab)Medicare Part D Prescribers - by Provider (CMS) (opens in a new tab) |
| MIPS scores, telehealth, assignment and procedure percentiles | Doctors and Clinicians National Downloadable File (CMS) (opens in a new tab)Clinician Public Reporting: Overall MIPS Performance (CMS) (opens in a new tab) |
| Clinical trials and co-investigators | ClinicalTrials.gov (National Library of Medicine) (opens in a new tab)Dmand AI Research Linkage |
| Industry payments | Open Payments (CMS) (opens in a new tab) |
| Training, board certification and memberships | Dmand AI Professional Profile Data |
| 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 Dr. Jonathan Kay
Spotted something out of date? Email hello@dmand.ai and we will check the record. Contact details live in the free trial.
What is Dr. Jonathan Kay's NPI number?
Dr. Jonathan Kay's NPI number is 1699766964. It was assigned on November 4, 2005, and it is active in the NPI Registry.
What kind of doctor is Dr. Jonathan Kay?
Dr. Jonathan Kay is a rheumatologist in Mendon, Massachusetts. The primary specialty in the NPI Registry is Rheumatology Physician (taxonomy code 207RR0500X).
Where does Dr. Jonathan Kay practice?
Dr. Kay practices at 55 North Ave, Mendon, MA 01756. Dr. Kay's primary practice is Umass Memorial Medical Center in Mendon, Massachusetts. Dmand AI also links Dr. Kay to 2 hospitals and 1 group practice or clinic.
What is Dr. Jonathan Kay's office phone number?
The practice phone on file for Dr. Kay is (508) 334-1000.
What is Dr. Jonathan Kay's medical license number?
Dr. Kay holds Massachusetts license 55522.
Which hospitals is Dr. Jonathan Kay affiliated with?
Dr. Kay is affiliated with UMass Memorial Medical Center - University Campus. Dmand AI links Dr. Kay to 2 more hospitals.
What medical group is Dr. Jonathan Kay part of?
Dr. Kay is linked to UMass Memorial Medical Group.
Does Dr. Jonathan Kay accept Medicare?
Yes. CMS data shows Dr. Kay billed Medicare for 273 services in 2024, and Dr. Kay accepts Medicare assignment.
What is Dr. Jonathan Kay's MIPS score?
Dr. Kay's MIPS final score for performance year 2024 is 100 out of 100, reported through an alternative payment model (APM).
How many Medicare patients does Dr. Jonathan Kay see?
CMS counts 127 Medicare patients who saw Dr. Kay in 2024, with an average age of 72.
Show 6 more questionsShow fewer questions
What services does Dr. Jonathan Kay bill to Medicare?
In 2024, Dr. Kay's most billed Medicare services were office visit, established patient (99214), surgery: bones and joints (20610) and office visit, established patient (99213).
Where did Dr. Jonathan Kay go to medical school?
Dr. Kay graduated from University of California, San Francisco School of Medicine in 1983.
What drugs does Dr. Jonathan Kay prescribe most?
In 2024 Medicare Part D data, Dr. Kay's most prescribed drugs by claims were Methotrexate, Allopurinol and Humira(Cf) Pen.
Has Dr. Jonathan Kay received payments from drug or device companies?
CMS Open Payments shows $479,013 in general payments to Dr. Kay from 28 companies from 2016 to 2025. The largest total came from Sandoz Inc.
How long has Dr. Jonathan Kay been practicing?
Dr. Kay graduated from medical school in 1983, 43 years ago.
Does Dr. Jonathan Kay do research?
Dr. Kay has worked on 1 clinical trial.
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