Dennis S. O'Brien, PA-C
- Medicare patients, 2024
- 216
- Hospital affiliations
- 1
- Medical group
- 1
- State license
- 1
- Year NPI issued
- 2006
- Practice address
- 759 Chestnut Street, Springfield, MA 01199
- Practice phone
- Call (413) 794-0000
- Professional email
- Get professional email
- Personal email
- Get personal email
- Mobile number
- Get mobile number
Primary practice
Find Dennis O'Brien's professional email, personal email and mobile number
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Dennis S. O'Brien is a physician assistant in Springfield, Massachusetts
Dennis O'Brien practices at Baystate Medical Center in Springfield, Massachusetts, part of Baystate Health.
Dennis O'Brien's NPI, 1407895956, was assigned on June 6, 2006. Dennis O'Brien holds Massachusetts license PA4779.
- NPI
- 1407895956NPI Registry (opens in a new tab)
- Medicare PAC ID
- 3274598388
- NPI enumeration date
- June 6, 2006
- NPI status
- Active
- Accepts Medicare assignment
- Yes
- Practice phone
- (413) 794-0000
- Professional email
- Get email
- Personal email
- Get email
- Mobile number
- Get number
- Sex
- Male
- Estimated age
- 48
- Medical school graduation
- 2004
Sources: NPPES NPI Registry (CMS); Dmand AI Professional Profile Data; Dmand AI Affiliation Data; and Doctors and Clinicians National Downloadable File (CMS)
Dennis S. O'Brien practices at Baystate Medical Center in Springfield, Massachusetts
Dennis O'Brien's primary practice is Baystate Medical Center, at 759 Chestnut Street, Springfield, MA 01199 in Hampden County. The practice phone is (413) 794-0000.
- Baystate Medical Center759 Chestnut Street, Springfield, MA 01199 · Hampden CountyPhone(413) 794-0000
Source: Dmand AI Affiliation Data
Dennis S. O'Brien is affiliated with 2 sites of care and 1 medical group
Dennis O'Brien's primary practice is Baystate Medical Center in Springfield, Massachusetts, part of Baystate Health. The medical group on file is Baystate Medical Practices. Dmand AI also links Dennis O'Brien to 1 more group practice or clinic, named with a free account.
Sources: Dmand AI Affiliation Data; and Dmand AI Org Hierarchy Data
Dmand AI tracks the EHR system at Dennis S. O'Brien's practice
Dmand AI tracks the electronic health record (EHR) system at each site where Dennis O'Brien practices, 2 sites in all. Vendor and product names are available with a free account.
| Site | EHR vendor and product |
|---|---|
| Baystate Medical Center | Available with a free account |
| +1 more affiliated site | Available with a free account |
Source: Dmand AI Technology Install Data
For health IT teams
Dmand AI maps EHR vendors, IT decision makers and buying committees across Baystate Health and 6.2K+ hospitals, with verified contacts in the same login.
Dennis S. O'Brien is one of 725 physician assistants in Massachusetts
Medical is Dennis O'Brien's primary specialty in the NPI Registry, under taxonomy code 363AM0700X. Dennis O'Brien is licensed in Massachusetts.
Specialties and state licenses
- Medical physician assistant, MassachusettsPrimary
Physician assistants near Dennis O'Brien
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
Dennis S. O'Brien treated 216 Medicare patients in 2024, average age 73
CMS counts 216 Medicare patients who saw Dennis O'Brien in 2024. The largest group is 75 to 84, with 70 patients. 75% of them have high blood pressure, and 75% have high cholesterol. 42% are also on Medicaid. Their average risk score is 1.97, where 1.00 is the Medicare average, so they are sicker than most Medicare patients.
Across all payers, Dmand AI patient panel data puts Dennis O'Brien's median patient age at 74, with 57% women.
Dennis O'Brien's Medicare patients by age, 2024
Dennis O'Brien's Medicare patients by sex, 2024
- Women12357%
- Men9343%
Chronic conditions among Dennis O'Brien's Medicare patients, 2024
- High blood pressure75%
- High cholesterol75%
- Stroke or TIA75%
- Mood disorders53%
- Arthritis52%
- Anxiety49%
- Chronic kidney disease48%
- Depression47%
Share of Medicare patients with each condition. A patient can have several.
Dennis O'Brien'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
How Dennis S. O'Brien takes part in Medicare
Dennis O'Brien accepts Medicare assignment, so Medicare's approved amount is taken as full payment.
- Accepts Medicare assignment
- Yes
Source: Doctors and Clinicians National Downloadable File (CMS)
Sources for Dennis S. O'Brien'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) |
| MIPS scores, telehealth, assignment and procedure percentiles | Doctors and Clinicians National Downloadable File (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 Dennis S. O'Brien
Spotted something out of date? Email hello@dmand.ai and we will check the record. Contact details live in the free trial.
What is Dennis S. O'Brien's NPI number?
Dennis S. O'Brien's NPI number is 1407895956. It was assigned on June 6, 2006, and it is active in the NPI Registry.
What does Dennis S. O'Brien specialize in?
Dennis S. O'Brien is a physician assistant in Springfield, Massachusetts. The primary specialty in the NPI Registry is Medical Physician Assistant (taxonomy code 363AM0700X).
Where does Dennis S. O'Brien practice?
Dennis O'Brien practices at 759 Chestnut Street, Springfield, MA 01199. Dennis O'Brien's primary practice is Baystate Medical Center in Springfield, Massachusetts, part of Baystate Health. Dmand AI also links Dennis O'Brien to 1 group practice or clinic.
What is Dennis S. O'Brien's office phone number?
The practice phone on file for Dennis O'Brien is (413) 794-0000.
What is Dennis S. O'Brien's medical license number?
Dennis O'Brien holds Massachusetts license PA4779.
Which hospitals is Dennis S. O'Brien affiliated with?
Dennis O'Brien practices at Baystate Medical Center in Springfield, Massachusetts.
What medical group is Dennis S. O'Brien part of?
Dennis O'Brien is linked to Baystate Medical Practices.
Does Dennis S. O'Brien accept Medicare?
Yes. CMS lists Dennis O'Brien as accepting Medicare assignment.
How many Medicare patients does Dennis S. O'Brien see?
CMS counts 216 Medicare patients who saw Dennis O'Brien in 2024, with an average age of 73.
How long has Dennis S. O'Brien been practicing?
Dennis O'Brien graduated from medical school in 2004, 22 years ago.
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