Dr. Daniel Patrick O'Brien Jr., MD
- Medicare services, 2024
- 325
- Medicare patients, 2024
- 198
- Part D claims, 2024
- 523
- Hospital affiliations
- 1
- Industry payments
- $1,256
- Practice address
- 73 Sandpit Rd, Danbury, CT 06810
- Practice phone
- Call (203) 743-2400
- Professional email
- Get professional email
- Personal email
- Get personal email
- Mobile number
- Get mobile number
Primary practice
Danbury Surgery Center
Danbury, Connecticut
Find Dr. O'Brien'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.
Dr. Daniel Patrick O'Brien Jr. is a gastroenterologist in Danbury, Connecticut
Dr. O'Brien practices at Danbury Surgery Center in Danbury, Connecticut.
Dr. O'Brien's NPI, 1518132505, was assigned on April 29, 2008. Dr. O'Brien graduated from State University of New York Downstate Medical Center College of Medicine in 2008. Dr. O'Brien holds Connecticut license 53019.
- NPI
- 1518132505NPI Registry (opens in a new tab)
- Medicare PAC ID
- 1355566894
- NPI enumeration date
- April 29, 2008
- NPI status
- Active
- Accepts Medicare assignment
- Yes
- Offers telehealth
- Yes
- Practice phone
- (203) 743-2400
- Professional email
- Get email
- Personal email
- Get email
- Mobile number
- Get number
- Sex
- Male
- Estimated age
- 44
- Medical school graduation
- 2008
Sources: NPPES NPI Registry (CMS); Dmand AI Professional Profile Data; Dmand AI Practice Data; and Doctors and Clinicians National Downloadable File (CMS)
Dr. Daniel Patrick O'Brien Jr. practices at Danbury Surgery Center in Danbury, Connecticut
Dr. O'Brien's primary practice is Danbury Surgery Center, at 73 Sandpit Rd, Danbury, CT 06810 in Western Ct County. The practice phone is (203) 743-2400.
- Danbury Surgery Center73 Sandpit Rd, Danbury, CT 06810 · Western Ct CountyPhone(203) 743-2400
Sources: NPPES NPI Registry (CMS); and Dmand AI Practice Data
Dr. Daniel Patrick O'Brien Jr. is affiliated with 4 sites of care and 2 medical groups
Dr. O'Brien's primary practice is Danbury Surgery Center in Danbury, Connecticut. Dr. O'Brien is also affiliated with Northwell Danbury Hospital. The medical group on file is Danbury Medical Group. Dmand AI also links Dr. O'Brien to 2 more group practices and clinics and 1 medical group, each named with a free account.
Sources: NPPES NPI Registry (CMS); Dmand AI Practice Data; and Dmand AI Affiliation Data
Dmand AI tracks the EHR system at Dr. Daniel Patrick O'Brien Jr.'s practice
Dmand AI tracks the electronic health record (EHR) system at each site where Dr. O'Brien practices, 3 sites in all. Vendor and product names are available with a free account.
| Site | EHR vendor and product |
|---|---|
| Danbury Surgery Center | Available with a free account |
| +3 more sites and 1 medical group | Available with a free account |
Source: Dmand AI Technology Install Data
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Dr. Daniel Patrick O'Brien Jr. is one of 298 gastroenterologists in Connecticut
Gastroenterology is Dr. O'Brien's primary specialty in the NPI Registry, under taxonomy code 207RG0100X. Dr. O'Brien is licensed in Connecticut.
Specialties and state licenses
- Gastroenterology, ConnecticutPrimary
Gastroenterologists near Dr. O'Brien
Counts of gastroenterologists 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. Daniel Patrick O'Brien Jr. billed Medicare for 325 services in 2024
CMS data shows 325 Medicare services from Dr. O'Brien across 5 procedure codes in 2024, for 198 Medicare patients. Medicare paid $35,835 for them.
Dr. O'Brien's Medicare services by type, 2023 to 2024
- 2023
- 2024
- Surgery
- 2023: 1802024: 1668%
- Office and hospital visits
- 2023: 1652024: 1594%
Where Dr. O'Brien's Medicare services took place, 2024
- In an office15949%
- In a facility16651%
Dr. O'Brien compared with the Connecticut median for gastroenterologists, 2024
- Dr. O'Brien
- Connecticut median
- Medicare services
- 325vs 36110% below
- Medicare patients
- 198vs 25322% below
- Part D claims
- 380vs 53829% below
Medians across 284 gastroenterologists in Connecticut with Dmand AI profiles that report each measure.
Dr. O'Brien'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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Medicare shows one payer. Book a meeting to get commercial claims data for Dr. O'Brien and other gastroenterologists in Connecticut.
Sources: Medicare Physician & Other Practitioners - by Provider and Service (CMS), 2024 data; and Dmand AI Peer Benchmarks
Dr. Daniel Patrick O'Brien Jr. treated 198 Medicare patients in 2024, average age 74
CMS counts 198 Medicare patients who saw Dr. O'Brien in 2024. The largest group is 65 to 74, with 98 patients. 75% of them have high cholesterol, and 71% have high blood pressure. 16% are also on Medicaid. Their average risk score is 1.28, where 1.00 is the Medicare average.
Across all payers, Dmand AI patient panel data puts Dr. O'Brien's median patient age at 58, with 47% women.
Dr. O'Brien's Medicare patients by age, 2024
Dr. O'Brien's Medicare patients by sex, 2024
- Women10553%
- Men9347%
Chronic conditions among Dr. O'Brien's Medicare patients, 2024
- High cholesterol75%
- High blood pressure71%
- Arthritis48%
- Diabetes31%
- Ischemic heart disease29%
- Anxiety25%
- Cancer22%
- Mood disorders22%
Share of Medicare patients with each condition. A patient can have several.
Dr. 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 58
Patient panel by sex, all payers
- Women47%
- Men51%
Sources: Dmand AI Patient Panel Data; and Medicare Physician & Other Practitioners - by Provider (CMS), 2024 data
Dr. Daniel Patrick O'Brien Jr. wrote 523 Medicare Part D claims in 2024
In 2024, Dr. O'Brien wrote 523 Medicare Part D claims for 195 patients. 91% of them were for generic drugs. CMS names the drug for 380 of them, across 6 drugs with 11 or more claims each, at $17,783 in total drug cost. In 2023, CMS named 366 claims across 8 drugs.
Dr. O'Brien's Part D claims by kind of drug, 2024
- Generic476 claims91%
- Brand-name47 claims9%
Dr. O'Brien'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.
Drug classes CMS tracks in Dr. O'Brien's Part D claims, 2024
- Antibiotics2%13 of 523 claims
Share of all Part D claims for each drug class CMS reports on. Classes with no claims are left out.
Part D claims for drugs CMS names, 2023 to 2024
- 2023
- 2024
- Claims for drugs CMS names
- 2023: 3662024: 3804%
Drugs named by CMS: 6 in 2024, 8 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. Daniel Patrick O'Brien Jr. ranks in the 67th percentile for colonoscopy in Medicare
Dr. O'Brien accepts Medicare assignment, so Medicare's approved amount is taken as full payment. CMS lists Dr. O'Brien as offering telehealth. CMS counts 60 procedures of colonoscopy by Dr. O'Brien, more than 67% of the clinicians it reports for that procedure.
- Accepts Medicare assignment
- Yes
- Offers telehealth
- Yes
Where Dr. O'Brien ranks in Medicare procedure volume
- Colonoscopy
- 67th percentile60 procedures
- Upper gastrointestinal (GI) endoscopy for acid reflux
- 66th percentile57 procedures
CMS ranks each clinician against every clinician it reports for the same procedure category.
Sources: Doctors and Clinicians National Downloadable File (CMS); and Doctors and Clinicians Utilization Data (CMS)
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Dr. Daniel Patrick O'Brien Jr. received $1,256 in industry payments from 2016 to 2023
CMS Open Payments shows 60 general payments to Dr. O'Brien from 24 drug and device companies from 2016 to 2023. Food and beverage make up the largest share, 100% of the total. Abbvie Inc. paid the most, $277.
General payments to Dr. O'Brien by program year, 2016 to 2023
Companies that paid Dr. O'Brien the most, 2016 to 2023
Share is of all general payments to this clinician.
Source: Open Payments (CMS), 2025 data, released July 7, 2026
Dr. Daniel Patrick O'Brien Jr. graduated from State University of New York Downstate Medical Center College of Medicine
Dr. O'Brien graduated from State University of New York Downstate Medical Center College of Medicine in 2008.
- Medical school
Source: Dmand AI Professional Profile Data
Sources for Dr. Daniel Patrick O'Brien Jr.'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)Doctors and Clinicians Utilization Data (CMS) (opens in a new tab) |
| 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. Daniel Patrick O'Brien Jr.
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. Daniel Patrick O'Brien Jr.'s NPI number?
Dr. Daniel Patrick O'Brien Jr.'s NPI number is 1518132505. It was assigned on April 29, 2008, and it is active in the NPI Registry.
What kind of doctor is Dr. Daniel Patrick O'Brien Jr.?
Dr. Daniel Patrick O'Brien Jr. is a gastroenterologist in Danbury, Connecticut. The primary specialty in the NPI Registry is Gastroenterology Physician (taxonomy code 207RG0100X).
Where does Dr. Daniel Patrick O'Brien Jr. practice?
Dr. O'Brien practices at 73 Sandpit Rd, Danbury, CT 06810. Dr. O'Brien's primary practice is Danbury Surgery Center in Danbury, Connecticut. Dmand AI also links Dr. O'Brien to 2 group practices and clinics and 1 medical group.
What is Dr. Daniel Patrick O'Brien Jr.'s office phone number?
The practice phone on file for Dr. O'Brien is (203) 743-2400.
What is Dr. Daniel Patrick O'Brien Jr.'s medical license number?
Dr. O'Brien holds Connecticut license 53019.
Which hospitals is Dr. Daniel Patrick O'Brien Jr. affiliated with?
Dr. O'Brien is affiliated with Northwell Danbury Hospital.
What medical group is Dr. Daniel Patrick O'Brien Jr. part of?
Dr. O'Brien is linked to Danbury Medical Group. Dmand AI links Dr. O'Brien to 1 more medical group.
Does Dr. Daniel Patrick O'Brien Jr. accept Medicare?
Yes. CMS data shows Dr. O'Brien billed Medicare for 325 services in 2024, and Dr. O'Brien accepts Medicare assignment.
Does Dr. Daniel Patrick O'Brien Jr. offer telehealth?
Yes. The CMS Doctors and Clinicians file lists Dr. O'Brien as offering telehealth services.
How many Medicare patients does Dr. Daniel Patrick O'Brien Jr. see?
CMS counts 198 Medicare patients who saw Dr. O'Brien in 2024, with an average age of 74.
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What services does Dr. Daniel Patrick O'Brien Jr. bill to Medicare?
In 2024, Dr. O'Brien's most billed Medicare services were office visit, established patient (99214), surgery: digestive system (43239) and surgery: digestive system (45380).
Where did Dr. Daniel Patrick O'Brien Jr. go to medical school?
Dr. O'Brien graduated from State University of New York Downstate Medical Center College of Medicine in 2008.
What drugs does Dr. Daniel Patrick O'Brien Jr. prescribe most?
In 2024 Medicare Part D data, Dr. O'Brien's most prescribed drugs by claims were Pantoprazole Sodium, Gavilyte-C and Omeprazole.
Has Dr. Daniel Patrick O'Brien Jr. received payments from drug or device companies?
CMS Open Payments shows $1,256 in general payments to Dr. O'Brien from 24 companies from 2016 to 2023. The largest total came from Abbvie Inc.
How long has Dr. Daniel Patrick O'Brien Jr. been practicing?
Dr. O'Brien graduated from medical school in 2008, 18 years ago.
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