Dr. William Chunghun Sim, MD
- Medicare services, 2024
- 5,538
- Medicare patients, 2024
- 787
- Part D claims, 2024
- 38,470
- MIPS score, 2024
- 75
- Hospital affiliations
- 3
- Practice address
- 11480 Brookshire Ave, Downey, CA 90241
- Practice phone
- Call (562) 806-0874
- Professional email
- Get professional email
- Personal email
- Get personal email
- Mobile number
- Get mobile number
Primary practice
Frischer Medical Group Inc
Downey, California
Find Dr. Sim's professional email, personal email and mobile number
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Dr. William Chunghun Sim is an internist in Downey, California
Dr. Sim practices at Frischer Medical Group Inc in Downey, California.
Dr. Sim's NPI, 1437256906, was assigned on September 19, 2006. Dr. Sim graduated from Stanford University School of Medicine in 1990. Dr. Sim holds California license G72353.
- NPI
- 1437256906NPI Registry (opens in a new tab)
- Medicare PAC ID
- 5698800910
- NPI enumeration date
- September 19, 2006
- NPI status
- Active
- Accepts Medicare assignment
- Yes
- Offers telehealth
- Yes
- Practice phone
- (562) 806-0874
- Professional email
- Get email
- Personal email
- Get email
- Mobile number
- Get number
- Sex
- Male
- Estimated age
- 62
- Medical school graduation
- 1990
Sources: NPPES NPI Registry (CMS); Dmand AI Professional Profile Data; Dmand AI Practice Data; and Doctors and Clinicians National Downloadable File (CMS)
Dr. William Chunghun Sim practices at Frischer Medical Group Inc in Downey, California
Dr. Sim's primary practice is Frischer Medical Group Inc, at 11480 Brookshire Ave, Downey, CA 90241 in Los Angeles County. The practice phone is (562) 806-0874.
- Frischer Medical Group Inc11480 Brookshire Ave, Downey, CA 90241 · Los Angeles CountyPhone(562) 806-0874
Sources: NPPES NPI Registry (CMS); and Dmand AI Practice Data
Dr. William Chunghun Sim is affiliated with 13 sites of care and 1 medical group
Dr. Sim's primary practice is Frischer Medical Group Inc in Downey, California. Dr. Sim is also affiliated with PIH Health Downey Hospital. The medical group on file is Frischer Medical Group. Dmand AI also links Dr. Sim to 2 more hospitals, 5 home health agencies, 2 hospices, 1 group practice or clinic and 1 skilled nursing facility, 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. William Chunghun Sim's practice
Dmand AI tracks the electronic health record (EHR) system at each site where Dr. Sim practices, 12 sites in all. Vendor and product names are available with a free account.
| Site | EHR vendor and product |
|---|---|
| Frischer Medical Group Inc | Available with a free account |
| +12 more affiliated sites | Available with a free account |
Source: Dmand AI Technology Install Data
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Dr. William Chunghun Sim is one of 16,751 internists in California
Internal medicine is Dr. Sim's primary specialty in the NPI Registry, under taxonomy code 207R00000X. Dr. Sim is licensed in California.
Specialties and state licenses
- Internal medicine, CaliforniaPrimary
Internists near Dr. Sim
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 Chunghun Sim billed Medicare for 5,538 services in 2024
CMS data shows 5,538 Medicare services from Dr. Sim across 17 procedure codes in 2024, for 787 Medicare patients. Medicare paid $373,241 for them. Every service was in an office.
Dr. Sim's Medicare services by type, 2023 to 2024
- 2023
- 2024
- Office and hospital visits
- 2023: 3,9712024: 3,954No change
- Drugs given in the office
- 2023: 3462024: 889157%
- Other services
- 2023: 2122024: 435105%
- Tests and treatments
- 2023: 2512024: 16036%
- Surgery
- 2023: 492024: 538%
- Lab and pathology
- 2023: 632024: 4725%
Dr. Sim compared with the California median for internists, 2024
- Dr. Sim
- California median
- Medicare services
- 5,538vs 36115.3 times
- Medicare patients
- 787vs 1515.2 times
- Part D claims
- 37,524vs 42189.1 times
Medians across 15,815 internists in California with Dmand AI profiles that report each measure.
Dr. Sim'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. William Chunghun Sim treated 787 Medicare patients in 2024, average age 80
CMS counts 787 Medicare patients who saw Dr. Sim in 2024. The largest group is 85 and over, with 282 patients. 75% of them have diabetes, and 75% have high blood pressure. 59% are also on Medicaid. Their average risk score is 1.64, 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. Sim's median patient age at 67, with 53% women.
Dr. Sim's Medicare patients by age, 2024
Dr. Sim's Medicare patients by sex, 2024
- Women47861%
- Men30939%
Chronic conditions among Dr. Sim's Medicare patients, 2024
- Diabetes75%
- High blood pressure75%
- High cholesterol75%
- Arthritis68%
- Alzheimer's and dementia42%
- Mood disorders36%
- Depression35%
- Anxiety28%
Share of Medicare patients with each condition. A patient can have several.
Dr. Sim's patients across all payers
Dmand AI patient panel data covers Medicare, Medicaid and commercial patients.
Patient panel by age, all payers
Median age 67
Patient panel by sex, all payers
- Women53%
- Men46%
Sources: Dmand AI Patient Panel Data; and Medicare Physician & Other Practitioners - by Provider (CMS), 2024 data
Dr. William Chunghun Sim wrote 38,470 Medicare Part D claims in 2024
In 2024, Dr. Sim wrote 38,470 Medicare Part D claims for 1,252 patients. 86% of them were for generic drugs. CMS names the drug for 37,524 of them, across 274 drugs with 11 or more claims each, at $3,393,626 in total drug cost. In 2023, CMS named 31,115 claims across 261 drugs.
Dr. Sim's Part D claims by kind of drug, 2024
- Generic33,050 claims86%
- Brand-name5,221 claims14%
- Other199 claims1%
Dr. Sim'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. Sim's Part D claims, 2024
- Opioids1%325 of 38,470 claims
- Antibiotics3%1,136 of 38,470 claims
- Antipsychotics, patients 65 and over2%801 of 38,470 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: 31,1152024: 37,52421%
Drugs named by CMS: 274 in 2024, 261 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. William Chunghun Sim scored 75 out of 100 in Medicare's MIPS program for 2024
CMS publishes a Merit-based Incentive Payment System (MIPS) score of 75 out of 100 for Dr. Sim for performance year 2024, reported individually. Dr. Sim accepts Medicare assignment, so Medicare's approved amount is taken as full payment. CMS lists Dr. Sim as offering telehealth.
- Accepts Medicare assignment
- Yes
- Offers telehealth
- Yes
- MIPS final score, 2024
- 75 of 100
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. William Chunghun Sim received $13,959 in industry payments from 2016 to 2025
CMS Open Payments shows 736 general payments to Dr. Sim from 76 drug and device companies from 2016 to 2025. Food and beverage make up the largest share, 100% of the total. Abbvie Inc. paid the most, $1,469.
General payments to Dr. Sim by program year, 2016 to 2025
General payments to Dr. Sim by kind, 2016 to 2025
- Food and beverage$13,944100%
- Education$160%
Companies that paid Dr. Sim 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 Chunghun Sim graduated from Stanford University School of Medicine
Dr. Sim graduated from Stanford University School of Medicine in 1990.
- Medical school
Source: Dmand AI Professional Profile Data
Sources for Dr. William Chunghun Sim'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) |
| 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. William Chunghun Sim
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 Chunghun Sim's NPI number?
Dr. William Chunghun Sim's NPI number is 1437256906. It was assigned on September 19, 2006, and it is active in the NPI Registry.
What kind of doctor is Dr. William Chunghun Sim?
Dr. William Chunghun Sim is an internist in Downey, California. The primary specialty in the NPI Registry is Internal Medicine Physician (taxonomy code 207R00000X).
Where does Dr. William Chunghun Sim practice?
Dr. Sim practices at 11480 Brookshire Ave, Downey, CA 90241. Dr. Sim's primary practice is Frischer Medical Group Inc in Downey, California. Dmand AI also links Dr. Sim to 2 hospitals, 5 home health agencies, 2 hospices, 1 group practice or clinic and 1 skilled nursing facility.
What is Dr. William Chunghun Sim's office phone number?
The practice phone on file for Dr. Sim is (562) 806-0874.
What is Dr. William Chunghun Sim's medical license number?
Dr. Sim holds California license G72353.
Which hospitals is Dr. William Chunghun Sim affiliated with?
Dr. Sim is affiliated with PIH Health Downey Hospital. Dmand AI links Dr. Sim to 2 more hospitals.
What medical group is Dr. William Chunghun Sim part of?
Dr. Sim is linked to Frischer Medical Group.
Does Dr. William Chunghun Sim accept Medicare?
Yes. CMS data shows Dr. Sim billed Medicare for 5,538 services in 2024, and Dr. Sim accepts Medicare assignment.
Does Dr. William Chunghun Sim offer telehealth?
Yes. The CMS Doctors and Clinicians file lists Dr. Sim as offering telehealth services.
What is Dr. William Chunghun Sim's MIPS score?
Dr. Sim's MIPS final score for performance year 2024 is 75 out of 100, reported individually.
Show 6 more questionsShow fewer questions
How many Medicare patients does Dr. William Chunghun Sim see?
CMS counts 787 Medicare patients who saw Dr. Sim in 2024, with an average age of 80.
What services does Dr. William Chunghun Sim bill to Medicare?
In 2024, Dr. Sim's most billed Medicare services were home visit (99349), office visit, established patient (99214) and office visit, established patient (99213).
Where did Dr. William Chunghun Sim go to medical school?
Dr. Sim graduated from Stanford University School of Medicine in 1990.
What drugs does Dr. William Chunghun Sim prescribe most?
In 2024 Medicare Part D data, Dr. Sim's most prescribed drugs by claims were Atorvastatin Calcium, Losartan Potassium and Amlodipine Besylate.
Has Dr. William Chunghun Sim received payments from drug or device companies?
CMS Open Payments shows $13,959 in general payments to Dr. Sim from 76 companies from 2016 to 2025. The largest total came from Abbvie Inc.
How long has Dr. William Chunghun Sim been practicing?
Dr. Sim graduated from medical school in 1990, 36 years ago.
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