Willis L. Chang
- Medicare services, 2016
- 754
- Part D claims, 2024
- 174
- Hospital affiliations
- 1
- Industry payments
- $1,221
- Medical group
- 1
- Practice address
- 1000 W Carson St, Torrance, CA 90509
- Practice phone
- Call (310) 222-2345
- Professional email
- Get professional email
- Personal email
- Get personal email
- Mobile number
- Get mobile number
Primary practice
Find Willis Chang'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.
Willis L. Chang is an internist in Torrance, California
Willis Chang practices at Harbor-UCLA Medical Center in Torrance, California, part of County of Los Angeles.
Willis Chang's NPI, 1831496538, was assigned on February 16, 2011. Willis Chang graduated from University of Medicine 2 Yangon in 2002. Willis Chang holds California license A130760.
- NPI
- 1831496538NPI Registry (opens in a new tab)
- Medicare PAC ID
- 8820210990
- NPI enumeration date
- February 16, 2011
- NPI status
- Active
- Accepts Medicare assignment
- Yes
- Practice phone
- (310) 222-2345
- Professional email
- Get email
- Personal email
- Get email
- Mobile number
- Get number
- Sex
- Male
- Estimated age
- 51
- Medical school graduation
- 2002
Sources: NPPES NPI Registry (CMS); Dmand AI Professional Profile Data; Dmand AI Affiliation Data; and Doctors and Clinicians National Downloadable File (CMS)
Willis L. Chang practices at Harbor-UCLA Medical Center in Torrance, California
Willis Chang's primary practice is Harbor-UCLA Medical Center, at 1000 W Carson St, Torrance, CA 90509 in Los Angeles County. The practice phone is (310) 222-2345.
- Harbor-UCLA Medical Center1000 W Carson St, Torrance, CA 90509 · Los Angeles CountyPhone(310) 222-2345
Source: Dmand AI Affiliation Data
Willis L. Chang is affiliated with 1 site of care and 1 medical group
Willis Chang's primary practice is Harbor-UCLA Medical Center in Torrance, California, part of County of Los Angeles. The medical group on file is Harbor-UCLA Medical Center.
Sources: Dmand AI Affiliation Data; and Dmand AI Org Hierarchy Data
Dmand AI tracks the EHR system at Willis L. Chang's practice
Dmand AI tracks the electronic health record (EHR) system at each site where Willis Chang practices. Vendor and product names are available with a free account.
| Site | EHR vendor and product |
|---|---|
| Harbor-UCLA Medical Center | 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 County of Los Angeles and 6.2K+ hospitals, with verified contacts in the same login.
Willis L. Chang is one of 16,751 internists in California
Internal medicine is Willis Chang's primary specialty in the NPI Registry, under taxonomy code 207R00000X. Willis Chang is board certified in internal medicine by the American Board of Internal Medicine. Dmand AI has Willis Chang's licenses on file in 2 states: California and New York.
Specialties and state licenses
- Internal medicine, CaliforniaPrimary
- New York license
Internists near Willis Chang
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
Willis L. Chang billed Medicare for 754 services in 2016
CMS data shows 754 Medicare services from Willis Chang across 16 procedure codes in 2016. Medicare paid $25,714 for them. Every service was in an office.
Willis Chang's Medicare services by type, 2016
- Office and hospital visits300
- Lab and pathology276
- Surgery104
- Other services54
- Tests and treatments20
Willis Chang compared with the California median for internists, 2016
- Willis Chang
- California median
- Medicare services
- 754vs 3612.1 times
- Part D claims
- 60vs 42186% below
Medians across 15,815 internists in California with Dmand AI profiles that report each measure.
Willis Chang's most billed Medicare procedure codes, 2016
CMS publishes codes billed for 11 or more Medicare patients. Each label is the code family; CPT descriptions are licensed by the AMA.
Need commercial claims for Willis Chang?
Medicare shows one payer. Book a meeting to get commercial claims data for Willis Chang and other internists in California.
Sources: Medicare Physician & Other Practitioners - by Provider and Service (CMS), 2024 data; and Dmand AI Peer Benchmarks
Willis L. Chang's patients have a median age of 58
Across all payers, Dmand AI patient panel data puts Willis Chang's median patient age at 58, with 40% women.
Willis Chang'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
- Women40%
- Men60%
Source: Dmand AI Patient Panel Data
Willis L. Chang wrote 174 Medicare Part D claims in 2024
In 2024, Willis Chang wrote 174 Medicare Part D claims for 53 patients. 91% of them were for generic drugs. CMS names the drug for 60 of them, across 3 drugs with 11 or more claims each, at $333 in total drug cost. In 2017, CMS named 61 claims across 4 drugs.
Willis Chang's Part D claims by kind of drug, 2024
- Generic159 claims91%
- Brand-name15 claims9%
Willis Chang'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.
Part D claims for drugs CMS names, 2017 to 2024
- 2017
- 2024
- Claims for drugs CMS names
- 2017: 612024: 602%
Drugs named by CMS: 3 in 2024, 4 in 2017.
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 Willis L. Chang takes part in Medicare
Willis Chang 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)
For MedTech and pharma teams
Filter 7.4M+ HCPs by Medicare procedures, Part D drugs and Open Payments history, then reach them with verified contacts in one login.
Willis L. Chang received $1,221 in industry payments from 2016 to 2023
CMS Open Payments shows 67 general payments to Willis Chang from 19 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, $268.
General payments to Willis Chang by program year, 2016 to 2023
Companies that paid Willis Chang the most, 2016 to 2023
Share is of all general payments to this clinician.
Source: Open Payments (CMS), 2025 data, released July 7, 2026
Willis L. Chang graduated from University of Medicine 2 Yangon
Willis Chang graduated from University of Medicine 2 Yangon in 2002.
- Medical school
- Board certified in internal medicine
Source: Dmand AI Professional Profile Data
Willis L. Chang accepts plans from 2 insurance carriers
Willis Chang is in network with 2 carriers, including HCSC and LA Care. HMO plans come from the most carriers, 1. Check the plan with the practice before a visit.
- HCSC
- LA Care
Plan types Willis Chang accepts, by number of carriers
- HMO1
- Medicaid1
- Medicare1
- PPO1
Source: Dmand AI Insurance Network Data
Sources for Willis L. Chang'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 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 Data |
| 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) |
| 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 Willis L. Chang
Spotted something out of date? Email hello@dmand.ai and we will check the record. Contact details live in the free trial.
What is Willis L. Chang's NPI number?
Willis L. Chang's NPI number is 1831496538. It was assigned on February 16, 2011, and it is active in the NPI Registry.
What does Willis L. Chang specialize in?
Willis L. Chang is an internist in Torrance, California. The primary specialty in the NPI Registry is Internal Medicine Physician (taxonomy code 207R00000X).
Where does Willis L. Chang practice?
Willis Chang practices at 1000 W Carson St, Torrance, CA 90509. Willis Chang's primary practice is Harbor-UCLA Medical Center in Torrance, California, part of County of Los Angeles.
What is Willis L. Chang's office phone number?
The practice phone on file for Willis Chang is (310) 222-2345.
What is Willis L. Chang's medical license number?
Willis Chang holds California license A130760, one of the licenses on file in 2 states.
Which states has Willis L. Chang been licensed in?
Dmand AI has state licenses on file for Willis Chang in California (2014 to 2026) and New York (2014 to 2016).
Which hospitals is Willis L. Chang affiliated with?
Willis Chang practices at Harbor-UCLA Medical Center in Torrance, California.
What medical group is Willis L. Chang part of?
Willis Chang is linked to Harbor-UCLA Medical Center.
Does Willis L. Chang accept Medicare?
Yes. CMS data shows Willis Chang billed Medicare for 754 services in 2016, and Willis Chang accepts Medicare assignment.
Is Willis L. Chang board certified?
Yes. Willis Chang is board certified in internal medicine by the American Board of Internal Medicine.
Show 6 more questionsShow fewer questions
What services does Willis L. Chang bill to Medicare?
In 2016, Willis Chang's most billed Medicare services were office visit, established patient (99213), surgery: heart and blood vessels (36415) and office visit, established patient (99214).
Where did Willis L. Chang go to medical school?
Willis Chang graduated from University of Medicine 2 Yangon in 2002.
What drugs does Willis L. Chang prescribe most?
In 2024 Medicare Part D data, Willis Chang's most prescribed drugs by claims were Atorvastatin Calcium, Amlodipine Besylate and Benazepril HCl.
Has Willis L. Chang received payments from drug or device companies?
CMS Open Payments shows $1,221 in general payments to Willis Chang from 19 companies from 2016 to 2023. The largest total came from Abbvie Inc.
How long has Willis L. Chang been practicing?
Willis Chang graduated from medical school in 2002, 24 years ago.
What insurance does Willis L. Chang accept?
Willis Chang is in network with 2 carriers, including HCSC and LA Care. HMO plans come from the most carriers, 1. Check the plan with the practice before a visit.
Selling to internal medicine practices?
See internists in California by site of care and group
Find the practices, groups and hospitals they work with, and the right people to contact at each.
- 30 days free
- Self-serve
- No credit card