Dr. Yih-Dar Nien, MD
- Medicare services, 2024
- 334
- Medicare patients, 2024
- 253
- Part D claims, 2024
- 130
- Publications
- 1
- MIPS score, 2024
- 93
- Practice address
- 1500 Duarte Rd, Duarte, CA 91010
- Practice phone
- Call (626) 256-4673
- Professional email
- Get professional email
- Personal email
- Get personal email
- Mobile number
- Get mobile number
Primary practice
City of Hope Comprehensive Cancer Center - Duarte
Duarte, California
Find Dr. Nien'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. Yih-Dar Nien is a general surgeon in Duarte, California
Dr. Nien practices at City of Hope Comprehensive Cancer Center - Duarte in Duarte, California.
Dr. Nien's NPI, 1164636262, was assigned on May 9, 2007. Dr. Nien graduated from Pontificia Universidad Catolica de Chile in 2001. Dr. Nien holds California license A101665.
- NPI
- 1164636262NPI Registry (opens in a new tab)
- Medicare PAC ID
- 9133292147
- NPI enumeration date
- May 9, 2007
- NPI status
- Active
- Accepts Medicare assignment
- Yes
- Offers telehealth
- Yes
- Practice phone
- (626) 256-4673
- Professional email
- Get email
- Personal email
- Get email
- Mobile number
- Get number
- Sex
- Male
- Estimated age
- 51
- Medical school graduation
- 2001
Sources: NPPES NPI Registry (CMS); Dmand AI Professional Profile Data; Dmand AI Practice Data; and Doctors and Clinicians National Downloadable File (CMS)
Dr. Yih-Dar Nien practices at City of Hope Comprehensive Cancer Center - Duarte in Duarte, California
Dr. Nien's primary practice is City of Hope Comprehensive Cancer Center - Duarte, at 1500 Duarte Rd, Duarte, CA 91010 in Los Angeles County. The practice phone is (626) 256-4673.
- City of Hope Comprehensive Cancer Center - Duarte1500 Duarte Rd, Duarte, CA 91010 · Los Angeles CountyPhone(626) 256-4673
Sources: NPPES NPI Registry (CMS); and Dmand AI Practice Data
Dr. Yih-Dar Nien is affiliated with 5 sites of care and 2 medical groups
Dr. Nien's primary practice is City of Hope Comprehensive Cancer Center - Duarte in Duarte, California. Dr. Nien is also affiliated with Ronald Reagan UCLA Medical Center. The medical group on file is UCLA Associated General Surgeons. Dmand AI also links Dr. Nien to 1 more hospital, 1 group practice or clinic, 1 other site and 1 medical group, each named with a free account.
Sources: NPPES NPI Registry (CMS); Dmand AI Practice Data; Dmand AI Affiliation Data; and Dmand AI Org Hierarchy Data
Dmand AI tracks the EHR system at Dr. Yih-Dar Nien's practice
Dmand AI tracks the electronic health record (EHR) system at each site where Dr. Nien practices, 4 sites in all. Vendor and product names are available with a free account.
| Site | EHR vendor and product |
|---|---|
| City of Hope Comprehensive Cancer Center - Duarte | Available with a free account |
| +4 more sites and 1 medical group | Available with a free account |
Source: Dmand AI Technology Install Data
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Dr. Yih-Dar Nien is one of 2,926 general surgeons in California
Surgery is Dr. Nien's primary specialty in the NPI Registry, under taxonomy code 208600000X. Dr. Nien is board certified in surgery by the American Board of Surgery. Dr. Nien is licensed in California.
Specialties and state licenses
- Surgery, CaliforniaPrimary
Clinical focus
Dmand AI lists abdominal adhesion surgery, abdominal hernia repair surgery, appendectomy, cancerous skin growth removal, colon removal, gallbladder removal, groin hernia surgery and hemorrhoids among the conditions Dr. Nien treats.
General surgeons near Dr. Nien
Counts of general surgeons 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. Yih-Dar Nien billed Medicare for 334 services in 2024
CMS data shows 334 Medicare services from Dr. Nien across 8 procedure codes in 2024, for 253 Medicare patients. Medicare paid $44,523 for them.
Dr. Nien's Medicare services by type, 2023 to 2024
- 2023
- 2024
- Office and hospital visits
- 2023: 2312024: 30833%
- Surgery
- 2023: 192024: 2637%
Where Dr. Nien's Medicare services took place, 2024
- In an office17954%
- In a facility15546%
Dr. Nien compared with the California median for general surgeons, 2024
- Dr. Nien
- California median
- Medicare services
- 334vs 1662.0 times
- Medicare patients
- 253vs 1212.1 times
- Part D claims
- 76vs 342.2 times
Medians across 2,606 general surgeons in California with Dmand AI profiles that report each measure.
Dr. Nien'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. Yih-Dar Nien treated 253 Medicare patients in 2024, average age 72
CMS counts 253 Medicare patients who saw Dr. Nien in 2024. The largest group is 65 to 74, with 133 patients. 75% of them have high blood pressure, and 75% have high cholesterol. 31% are also on Medicaid. Their average risk score is 2.09, 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. Nien's median patient age at 58, with 42% women.
Dr. Nien's Medicare patients by age, 2024
Dr. Nien's Medicare patients by sex, 2024
- Women12851%
- Men12549%
Chronic conditions among Dr. Nien's Medicare patients, 2024
- High blood pressure75%
- High cholesterol75%
- Arthritis52%
- Diabetes39%
- Ischemic heart disease38%
- Mood disorders34%
- Depression32%
- Anxiety30%
Share of Medicare patients with each condition. A patient can have several.
Dr. Nien'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
- Women42%
- Men57%
Sources: Dmand AI Patient Panel Data; and Medicare Physician & Other Practitioners - by Provider (CMS), 2024 data
Dr. Yih-Dar Nien wrote 130 Medicare Part D claims in 2024
In 2024, Dr. Nien wrote 130 Medicare Part D claims for 95 patients. 95% of them were for generic drugs. CMS names the drug for 76 of them, across 2 drugs with 11 or more claims each, at $213 in total drug cost. In 2023, CMS named 109 claims across 4 drugs.
Dr. Nien's Part D claims by kind of drug, 2024
- Generic123 claims95%
- Brand-name and other7 claims5%
Dr. Nien'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. Nien's Part D claims, 2024
- Opioids64%83 of 130 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: 1092024: 7630%
Drugs named by CMS: 2 in 2024, 4 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. Yih-Dar Nien scored 93 out of 100 in Medicare's MIPS program for 2024
CMS publishes a Merit-based Incentive Payment System (MIPS) score of 93 out of 100 for Dr. Nien for performance year 2024, reported as part of a group. Dr. Nien accepts Medicare assignment, so Medicare's approved amount is taken as full payment. CMS lists Dr. Nien as offering telehealth. CMS counts 41 procedures of hernia repair (minimally invasive) by Dr. Nien, more than 97% of the clinicians it reports for that procedure.
- Accepts Medicare assignment
- Yes
- Offers telehealth
- Yes
Dr. Nien's MIPS scores, performance year 2024
- 93of 100Final score
- 78.5of 100Quality
- 100of 100Promoting Interoperability
- 40of 100Improvement Activities
- 70of 100Cost
Each score is out of 100. The final score weighs the categories CMS scored for this clinician.
Where Dr. Nien ranks in Medicare procedure volume
- Hernia repair (minimally invasive)
- 97th percentile41 procedures
CMS ranks each clinician against every clinician it reports for the same procedure category.
Colonoscopy: 1 to 10 procedures (CMS shows small counts as a range)
Hernia repair - groin (open): 1 to 10 procedures (CMS shows small counts as a range)
Melanoma (skin cancer) excision: 1 to 10 procedures (CMS shows small counts as a range)
Upper gastrointestinal (GI) endoscopy for acid reflux: 1 to 10 procedures (CMS shows small counts as a range)
Sources: Doctors and Clinicians National Downloadable File (CMS); Clinician Public Reporting: Overall MIPS Performance (CMS), 2024 data, released September 10, 2026; and Doctors and Clinicians Utilization Data (CMS)
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Dr. Yih-Dar Nien has 1 publication on record
Dmand AI links 1 paper to Dr. Nien in 2025. Dr. Nien's most frequent co-authors are Sarah Matrisciano Gilyard and Michael W. Robinson.
Dr. Nien's most frequent co-authors
Recent publications by Dr. Nien
See who Dr. Nien researches with
Physician Network Discovery turns co-authorship, shared hospitals and shared groups into a map of who Dr. Nien works with, so you can find a warm path to the right general surgeons.
Sources: PubMed (National Library of Medicine); and Dmand AI Research Linkage
Dr. Yih-Dar Nien received $10,233 in industry payments from 2017 to 2024
CMS Open Payments shows 20 general payments to Dr. Nien from 7 drug and device companies from 2017 to 2024. Education make up the largest share, 88% of the total. Intuitive Surgical, Inc. paid the most, $10,038.
General payments to Dr. Nien by program year, 2017 to 2024
General payments to Dr. Nien by kind, 2017 to 2024
- Education$9,00088%
- Travel and lodging$7918%
- Food and beverage$4424%
Companies that paid Dr. Nien the most, 2017 to 2024
Share is of all general payments to this clinician.
Source: Open Payments (CMS), 2025 data, released July 7, 2026
Dr. Yih-Dar Nien graduated from Pontificia Universidad Catolica de Chile
Dr. Nien graduated from Pontificia Universidad Catolica de Chile in 2001.
- Medical school
- Board certified in surgery
Source: Dmand AI Professional Profile Data
Sources for Dr. Yih-Dar Nien'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 DataDmand AI Org Hierarchy 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)Doctors and Clinicians Utilization Data (CMS) (opens in a new tab) |
| Publications, topics and co-authors | PubMed (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. Yih-Dar Nien
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. Yih-Dar Nien's NPI number?
Dr. Yih-Dar Nien's NPI number is 1164636262. It was assigned on May 9, 2007, and it is active in the NPI Registry.
What kind of doctor is Dr. Yih-Dar Nien?
Dr. Yih-Dar Nien is a general surgeon in Duarte, California. The primary specialty in the NPI Registry is Surgery Physician (taxonomy code 208600000X).
Where does Dr. Yih-Dar Nien practice?
Dr. Nien practices at 1500 Duarte Rd, Duarte, CA 91010. Dr. Nien's primary practice is City of Hope Comprehensive Cancer Center - Duarte in Duarte, California. Dmand AI also links Dr. Nien to 1 hospital, 1 group practice or clinic, 1 other site and 1 medical group.
What is Dr. Yih-Dar Nien's office phone number?
The practice phone on file for Dr. Nien is (626) 256-4673.
What is Dr. Yih-Dar Nien's medical license number?
Dr. Nien holds California license A101665.
Which hospitals is Dr. Yih-Dar Nien affiliated with?
Dr. Nien is affiliated with Ronald Reagan UCLA Medical Center. Dmand AI links Dr. Nien to 1 more hospital.
What medical group is Dr. Yih-Dar Nien part of?
Dr. Nien is linked to UCLA Associated General Surgeons. Dmand AI links Dr. Nien to 1 more medical group.
Does Dr. Yih-Dar Nien accept Medicare?
Yes. CMS data shows Dr. Nien billed Medicare for 334 services in 2024, and Dr. Nien accepts Medicare assignment.
Does Dr. Yih-Dar Nien offer telehealth?
Yes. The CMS Doctors and Clinicians file lists Dr. Nien as offering telehealth services.
What is Dr. Yih-Dar Nien's MIPS score?
Dr. Nien's MIPS final score for performance year 2024 is 93 out of 100, reported as part of a group.
Show 9 more questionsShow fewer questions
How many Medicare patients does Dr. Yih-Dar Nien see?
CMS counts 253 Medicare patients who saw Dr. Nien in 2024, with an average age of 72.
Is Dr. Yih-Dar Nien board certified?
Yes. Dr. Nien is board certified in surgery by the American Board of Surgery.
What services does Dr. Yih-Dar Nien bill to Medicare?
In 2024, Dr. Nien's most billed Medicare services were office visit, new patient (99203), hospital inpatient care (99223) and office visit, established patient (99213).
Where did Dr. Yih-Dar Nien go to medical school?
Dr. Nien graduated from Pontificia Universidad Catolica de Chile in 2001.
What drugs does Dr. Yih-Dar Nien prescribe most?
In 2024 Medicare Part D data, Dr. Nien's most prescribed drugs by claims were Tramadol HCl and Hydrocodone-Acetaminophen.
Has Dr. Yih-Dar Nien received payments from drug or device companies?
CMS Open Payments shows $10,233 in general payments to Dr. Nien from 7 companies from 2017 to 2024. The largest total came from Intuitive Surgical, Inc.
How long has Dr. Yih-Dar Nien been practicing?
Dr. Nien graduated from medical school in 2001, 25 years ago.
Does Dr. Yih-Dar Nien do research?
Dmand AI links 1 publication to Dr. Nien.
Who does Dr. Yih-Dar Nien publish with?
Dr. Nien's most frequent co-authors are Sarah Matrisciano Gilyard (1 shared paper) and Michael W. Robinson (1 shared paper).
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