Elmer Y. Chang, M.D.
NPI 1912083353ActiveIndividual· Internal Medicine, Gastroenterology· Mission Viejo, CA
Internal Medicine, Gastroenterology (M.D.) in Mission Viejo, California, trained at Northwestern University Feinberg Medical School (class of 1998). Their prescriptions cost Medicare Part D more than their services did: $744,413 for 2,403 claims, against $123,141 paid for services in 2024. Abbvie Inc. was the largest of 22 companies reporting payments in 2025, $4,414 in all, mostly food and beverage.
Overview
| NPI | 1912083353 |
|---|---|
| Status | Active |
| Entity type | Individual |
| Credential | M.D. |
| Sole proprietor | No |
| NPI issued | Oct 28, 2006 |
| Last updated in NPPES | Jan 23, 2013 |
Specialties and licenses
| Taxonomy | Code | License | State |
|---|---|---|---|
| Internal Medicine, Gastroenterology Primary | 207RG0100X | A75579 | CA |
Exclusion screening
| List | Result | Details |
|---|---|---|
| HHS-OIG LEIE · Oct 9, 2026 | No match | Checked by NPI and by name + state |
| North Carolina Medicaid · Nov 10, 2026 | No match | — |
| New York OMIG · Nov 10, 2026 | No match | — |
| Ohio Medicaid · Nov 10, 2026 | No match | — |
| Pennsylvania Medicheck · Nov 10, 2026 | No match | — |
| Washington HCA · Nov 10, 2026 | No match | — |
Official OIG search · How matching works ·Bulk check a roster
Medicare
| Enrollment (PECOS) | Enrolled Practitioner - Gastroenterology (CA) |
|---|---|
| Accepts assignment | Yes (participating) |
Medicare services in 2024
| Medicare patients | 434 |
|---|---|
| Services billed | 1,341 across 47 procedure codes |
| Paid by Medicare | $123,141 |
Part D prescriptions in 2024
| Prescriptions (claims) | 2,403 · 5,754 30-day fills |
|---|---|
| Patients | 722 |
| Total drug cost | $744,413 |
| Generic share | 91% of claims |
Education and affiliations
| Medical school | Northwestern University Feinberg Medical School |
|---|---|
| Graduation year | 1998 |
| Medicare specialty | Gastroenterology |
| Telehealth | Offers telehealth |
Medical group
- Providence Medical FoundationVictorville, CA · 1,466 clinicians
Hospital affiliations
- Hoag Memorial Hospital PresbyterianNewport Beach, CA
- Providence Mission HospitalMission Viejo, CA
Industry payments (Open Payments)
- 2025$4,414 · 165 payments from 22 companies
- 2024$4,328 · 173 payments from 17 companies
Top paying companies in 2025
| Company | Amount | Payments |
|---|---|---|
| Abbvie Inc. | $1,080 | 46 |
| Janssen Biotech, Inc. | $852.75 | 22 |
| Pfizer Inc. | $355.65 | 13 |
| Madrigal Pharmaceuticals | $340.37 | 8 |
| Salix Pharmaceuticals, A Division of Bausch Health US, LLC | $337.40 | 15 |
What the 2025 payments were for
- Food and Beverage$4,414 · 165 payments
Receiving payments does not imply wrongdoing. What Open Payments covers ·original records
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All Internal Medicine, Gastroenterology providers in California →