Ian Chang, D.O.
Rheumatology Physician · Orange, CA
Ian Chang, D.O. is a rheumatology physician with a practice address in Orange, California, and NPI 1407116411, issued on May 23, 2012. Check the license (California 20A16850, as entered in NPPES) on the Medical Board of California; the Medicare figures below come from public CMS files.
- Name
- Ian Chang
- Credential
- D.O.
- Primary taxonomy
- Rheumatology Physician 207RR0500X
- License numbers
- 20A16850 CA
5101019682 MI
Self-reported in NPPES; status is on the state search - Practice location
- 101 The City Dr S Bldg 30, Orange, CA 92868
- Phone
- (714) 456-7720
- Enumerated
- May 23, 2012
- Record last updated
- Mar 29, 2023
- Entity
- Type 1 · individual
8 nearest rheumatology physician records → All 926 in California → Look up another NPI →
Also registered at 101 The City Dr S Bldg 30
A shared address usually means a shared clinic or building; it does not show who employs whom.
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Verify Ian Chang in five checks
- 1IdentityNPI record in CMS NPPESNPI lookupConfirmed in NPPES
- 2LicenseActive license and public ordersMedical Board of California
Search for license 20A16850Check the board - 3Other statesLicenses and actions elsewhereDocInfo (FSMB)Not checked
- 4ExclusionsMedicare and Medicaid bansHHS-OIG exclusion listNot checked
- 5CertificationBoard certificationABMS AOA NCCPA AANPNot checked
82% fewer Medicare Part D claims than the average rheumatology physician in 2024
361 Medicare Part D claims for 78 beneficiaries, against an average of 1,978 among the 6,301 providers of this specialty who prescribed in Part D. Brand-name drugs were 24% of claims.
Most prescribed
- Diclofenac Sodium38 claims
- Humira(Cf) Pen36 claims
- Methotrexate35 claims
- Prednisone35 claims
- Leflunomide26 claims
- Gabapentin21 claims
Source: CMS Medicare Part D Prescribers by Provider and Drug, 2024 (data.cms.gov). Part D covers prescriptions for Medicare patients only; drugs with fewer than 11 claims are not published.
The MIPS final score for 2023 (Medicare payment program): 100 of 100
The Merit-based Incentive Payment System score is reported for this clinician. Four categories are weighted into the final score; the average among 454,083 clinicians with a measured score was 83.5.
Source: CMS Quality Payment Program, MIPS performance year 2023; category weights for 2023 (qpp.cms.gov).
Ian Chang among 926 rheumatology physician records in California
Ian Chang, D.O. is one of 926 rheumatology physician records with a practice address in California. 81% of them appear in a Medicare file (Part D prescribing, MIPS, Open Payments or Medicare group billing); this one does. Its NPI, issued in 2012, is newer than 71% of them.
- NPI issued2012 · 71% of these records are older, 25% newer
- In a Medicare fileYes · 81% of these records are
- In the CMS Doctors and Clinicians fileNo · 69% of these records are
- Record last updated2023 · 62% of these records were not updated in five years or more
Source: CMS NPPES, file of Aug 9, 2026, every record with primary taxonomy 207RR0500X and a California practice address; Medicare files: CMS Part D Prescribers 2024, MIPS 2023, Open Payments 2024, Doctors and Clinicians (data.cms.gov).
Rheumatology Physician providers in California
There are 926 rheumatology physician records in California.
All 926 in California → Every provider in Orange → Rheumatology Physician nationwide →
The 8 rheumatology physician records with the nearest ZIP codes
- Brian S Andrews, MDOrange, CA 928681609970292
- Caroline BuiOrange, CA 928681821626482
- Michael Cheng, DOOrange, CA 928681003109513
- Sheetal Desai, MDOrange, CA 928681699966861
- Priyanka Iyer, M.B.B.S, M.P.HOrange, CA 928681245662055
- Behnam Khaleghi, MDOrange, CA 928681154306678
- George Lawry, MDOrange, CA 928681043208994
- Joo-Hyung Lee, MDOrange, CA 928681306891346
Common questions
What is Ian Chang, D.O.'s NPI number?
Ian Chang, D.O.'s National Provider Identifier (NPI) is 1407116411, issued on May 23, 2012. An NPI identifies a provider in billing; it is not a license.
Where is Ian Chang, D.O. located?
The NPPES record lists a practice address at 101 The City Dr S Bldg 30, Orange, CA, 92868. Phone: (714) 456-7720. Providers update this record themselves, so call before visiting.
How can I verify Ian Chang, D.O.'s license?
NPPES lists California license number 20A16850, as entered by the provider. Search the Medical Board of California at https://www.mbc.ca.gov/License-Verification/default.aspx. The NPPES record confirms identity only; the state search shows license status, expiration and public orders.
How much does Ian Chang, D.O. prescribe under Medicare Part D?
In 2024, Ian Chang, D.O. had 361 Medicare Part D claims for 78 beneficiaries; the average among rheumatology physician prescribers was 1,978. Part D covers Medicare prescriptions only.
What is Ian Chang, D.O.'s MIPS final score?
The 2023 MIPS final score is 100 of 100. The average among 454,083 clinicians with a measured score was 83.5.
Source: CMS National Plan and Provider Enumeration System (NPPES), file of Aug 9, 2026 (NPPES files on CMS.gov); NUCC Health Care Provider Taxonomy. Medicare files from data.cms.gov. An NPI identifies who bills; it is not a license.
Figures on PlainDoctor are read from the federal files each page names (CMS NPPES, Medicare Part D, MIPS, Open Payments; the HHS-OIG exclusion list only as counts) and from Census population estimates, with the file date shown beside them. See our editorial standards & corrections policy, the methodology behind these numbers, or report a data error. Data current as of Aug 9, 2026.