Dr. William Chen, MD
- Medicare patients, 2024
- 13
- Part D claims, 2024
- 2,043
- Hospital affiliations
- 1
- Industry payments
- $271
- Medical group
- 1
- Practice address
- 535 East First Street, Tustin, CA 92780
- Practice phone
- Call (714) 730-1428
- Professional email
- Get professional email
- Personal email
- Get personal email
- Mobile number
- Get mobile number
Primary practice
Fresenius Kidney Care East First Tustin
Dialysis Center - Independent · Tustin, California
Find Dr. Chen'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. William Chen is an internist in Tustin, California
Dr. Chen practices at Fresenius Kidney Care East First Tustin in Tustin, California.
Dr. Chen's NPI, 1881659142, was assigned on April 19, 2006. Dr. Chen graduated from Keck School of Medicine of USC in 2004. Dr. Chen holds California license A93575.
- NPI
- 1881659142NPI Registry (opens in a new tab)
- Medicare PAC ID
- 3072613579
- NPI enumeration date
- April 19, 2006
- NPI status
- Active
- Accepts Medicare assignment
- Yes
- Practice phone
- (714) 730-1428
- Professional email
- Get email
- Personal email
- Get email
- Mobile number
- Get number
- Sex
- Male
- Estimated age
- 52
- 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)
Dr. William Chen practices at Fresenius Kidney Care East First Tustin in Tustin, California
Dr. Chen's primary practice is Fresenius Kidney Care East First Tustin, at 535 East First Street, Tustin, CA 92780 in Orange County. The practice phone is (714) 730-1428.
- Fresenius Kidney Care East First Tustin535 East First Street, Tustin, CA 92780 · Orange CountyPhone(714) 730-1428
Source: Dmand AI Affiliation Data
Dr. William Chen is affiliated with 3 sites of care and 1 medical group
Dr. Chen's primary practice is Fresenius Kidney Care East First Tustin in Tustin, California. Dr. Chen is also affiliated with Orange County - Anaheim Medical Center. The medical group on file is Southern California Permanente Medical Group. Dmand AI also links Dr. Chen 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 Dr. William Chen's practice
Dmand AI tracks the electronic health record (EHR) system at each site where Dr. Chen practices, 3 sites in all. Vendor and product names are available with a free account.
| Site | EHR vendor and product |
|---|---|
| Fresenius Kidney Care East First Tustin | Available with a free account |
| +2 more affiliated sites | Available with a free account |
Source: Dmand AI Technology Install Data
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Dr. William Chen is one of 16,751 internists in California
Internal medicine is Dr. Chen's primary specialty in the NPI Registry, under taxonomy code 207R00000X. Dr. Chen is board certified in internal medicine by the American Board of Internal Medicine. Dr. Chen is licensed in California.
Specialties and state licenses
- Internal medicine, CaliforniaPrimary
Internists near Dr. Chen
Counts of internists 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. William Chen treated 13 Medicare patients in 2024, average age 66
CMS counts 13 Medicare patients who saw Dr. Chen in 2024. 75% of them have chronic kidney disease, and 75% have high blood pressure. Their average risk score is 3.94, where 1.00 is the Medicare average, so they are sicker than most Medicare patients.
Across all payers, Dmand AI patient panel data puts Dr. Chen's median patient age at 63, with 46% women.
Chronic conditions among Dr. Chen's Medicare patients, 2024
- Chronic kidney disease75%
- High blood pressure75%
Share of Medicare patients with each condition. A patient can have several.
Dr. Chen's patients across all payers
Dmand AI patient panel data covers Medicare, Medicaid and commercial patients.
Patient panel by age, all payers
Median age 63
Patient panel by sex, all payers
- Women46%
- Men53%
Sources: Dmand AI Patient Panel Data; and Medicare Physician & Other Practitioners - by Provider (CMS), 2024 data
Dr. William Chen wrote 2,043 Medicare Part D claims in 2024
In 2024, Dr. Chen wrote 2,043 Medicare Part D claims for 358 patients. 95% of them were for generic drugs. CMS names the drug for 1,747 of them, across 31 drugs with 11 or more claims each, at $87,673 in total drug cost. In 2023, CMS named 1,794 claims across 34 drugs.
Dr. Chen's Part D claims by kind of drug, 2024
- Generic1,950 claims95%
- Brand-name93 claims5%
Dr. Chen'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. Chen's Part D claims, 2024
- Antibiotics4%76 of 2,043 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: 1,7942024: 1,7473%
Drugs named by CMS: 31 in 2024, 34 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
How Dr. William Chen takes part in Medicare
Dr. Chen 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)
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Dr. William Chen received $271 in industry payments from 2016 to 2025
CMS Open Payments shows 8 general payments to Dr. Chen from 7 drug and device companies from 2016 to 2025. Food and beverage make up the largest share, 100% of the total. Gilead Sciences, Inc. paid the most, $102.
General payments to Dr. Chen by program year, 2016 to 2025
Companies that paid Dr. Chen 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. William Chen has 1 award and honors on record
Dmand AI lists 1 award for Dr. Chen, most recently CMS Stage 1 2012 in 2011.
Awards and honors for Dr. Chen
- 2011
- CMS Stage 1 2012
Source: Dmand AI Professional Profile Data
Dr. William Chen graduated from Keck School of Medicine of USC
Dr. Chen graduated from Keck School of Medicine of USC in 2004. Dr. Chen is a member of ACP.
- Medical school
- Board certified in internal medicine
- Board certified in nephrology
Source: Dmand AI Professional Profile Data
Dr. William Chen accepts plans from 6 insurance carriers
Dr. Chen is in network with 6 carriers, including Elevance, Kaiser Permanente and Blue Cross Blue Shield of Massachusetts. Medicare plans come from the most carriers, 5. Check the plan with the practice before a visit.
- Elevance
- Kaiser Permanente
- Blue Cross Blue Shield of Massachusetts
- Blue Cross Blue Shield of Michigan
- HCSC
- CMS Medicare
Plan types Dr. Chen accepts, by number of carriers
- Medicare5
- PPO4
- HMO2
- POS2
- EPO1
Source: Dmand AI Insurance Network Data
Sources for Dr. William Chen'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 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) |
| Industry payments | Open Payments (CMS) (opens in a new tab) |
| Awards and committee roles | Dmand AI Professional Profile Data |
| Training, board certification and memberships | Dmand AI Professional Profile Data |
| Insurance carriers and plan types | Dmand AI Insurance Network 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. William Chen
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. William Chen's NPI number?
Dr. William Chen's NPI number is 1881659142. It was assigned on April 19, 2006, and it is active in the NPI Registry.
What kind of doctor is Dr. William Chen?
Dr. William Chen is an internist in Tustin, California. The primary specialty in the NPI Registry is Internal Medicine Physician (taxonomy code 207R00000X).
Where does Dr. William Chen practice?
Dr. Chen practices at 535 East First Street, Tustin, CA 92780. Dr. Chen's primary practice is Fresenius Kidney Care East First Tustin in Tustin, California. Dmand AI also links Dr. Chen to 1 group practice or clinic.
What is Dr. William Chen's office phone number?
The practice phone on file for Dr. Chen is (714) 730-1428.
What is Dr. William Chen's medical license number?
Dr. Chen holds California license A93575.
Which hospitals is Dr. William Chen affiliated with?
Dr. Chen is affiliated with Orange County - Anaheim Medical Center.
What medical group is Dr. William Chen part of?
Dr. Chen is linked to Southern California Permanente Medical Group.
Does Dr. William Chen accept Medicare?
Yes. CMS lists Dr. Chen as accepting Medicare assignment.
How many Medicare patients does Dr. William Chen see?
CMS counts 13 Medicare patients who saw Dr. Chen in 2024, with an average age of 66.
Is Dr. William Chen board certified?
Yes. Dr. Chen is board certified in internal medicine by the American Board of Internal Medicine.
Show 5 more questionsShow fewer questions
Where did Dr. William Chen go to medical school?
Dr. Chen graduated from Keck School of Medicine of USC in 2004.
What drugs does Dr. William Chen prescribe most?
In 2024 Medicare Part D data, Dr. Chen's most prescribed drugs by claims were Furosemide, Losartan Potassium and Lisinopril.
Has Dr. William Chen received payments from drug or device companies?
CMS Open Payments shows $271 in general payments to Dr. Chen from 7 companies from 2016 to 2025. The largest total came from Gilead Sciences, Inc.
How long has Dr. William Chen been practicing?
Dr. Chen graduated from medical school in 2004, 22 years ago.
What insurance does Dr. William Chen accept?
Dr. Chen is in network with 6 carriers, including Elevance, Kaiser Permanente and Blue Cross Blue Shield of Massachusetts. Medicare plans come from the most carriers, 5. Check the plan with the practice before a visit.
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