Warren Chang, MD
NPI 1083674550ActiveIndividual· Internal Medicine, Nephrology· Daly City, CA
Internal Medicine, Nephrology (MD) with North East Medical Services and 1 other group, practicing in Daly City, California. Their prescriptions cost Medicare Part D more than their services did: $526,413 for 2,178 claims, against $237,697 paid for services in 2024. Astrazeneca Pharmaceuticals LP was the largest of 20 companies reporting payments in 2025, $2,086 in all, mostly food and beverage. Lists Ahmc Seton Medical Center and 4 other hospitals as hospital affiliations.
Overview
| NPI | 1083674550 |
|---|---|
| Status | Active |
| Entity type | Individual |
| Credential | MD |
| Sole proprietor | Yes |
| NPI issued | Mar 27, 2006 |
| Last updated in NPPES | Aug 26, 2019 |
Specialties and licenses
| Taxonomy | Code | License | State |
|---|---|---|---|
| Internal Medicine, Nephrology Primary | 207RN0300X | AG9500 | 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 - Nephrology (CA) |
|---|---|
| Accepts assignment | Yes (participating) |
Medicare services in 2024
| Medicare patients | 448 |
|---|---|
| Services billed | 2,392 across 44 procedure codes |
| Paid by Medicare | $237,697 |
Part D prescriptions in 2024
| Prescriptions (claims) | 2,178 · 4,971 30-day fills |
|---|---|
| Patients | 319 |
| Total drug cost | $526,413 |
| Generic share | 78% of claims |
Education and affiliations
| Graduation year | 1998 |
|---|---|
| Medicare specialty | Nephrology |
| Telehealth | Offers telehealth |
Medical groups
- North East Medical ServicesSouth San Francisco, CA · 143 clinicians
- West Coast KidneyDaly City, CA · 56 clinicians
Hospital affiliations
- Ahmc Seton Medical CenterDaly City, CA
- California Pacific Medical Center - Mission BernalSan Francisco, CA
- Peninsula Medical CenterBurlingame, CA
- UCSF Health St. Mary's HospitalSan Francisco, CA
- UCSF Medical CenterSan Francisco, CA
Other facilities
- Davita Colma DialysisDialysis facility · Colma, CA
- Davita Daly City DialysisDialysis facility · Daly City, CA
- Davita San Francisco DialysisDialysis facility · San Francisco, CA
- Davita South San Francisco at Home (Pd)Dialysis facility · South San Francisco, CA
- Davita Westlake Daly City Dialysis CenterDialysis facility · Daly City, CA
Industry payments (Open Payments)
- 2025$2,086 · 80 payments from 20 companies
- 2024$1,440 · 60 payments from 18 companies
Top paying companies in 2025
| Company | Amount | Payments |
|---|---|---|
| Astrazeneca Pharmaceuticals LP | $317.92 | 13 |
| Novo Nordisk Inc | $294.37 | 14 |
| Novartis Pharmaceuticals Corporation | $222.85 | 8 |
| Mallinckrodt Hospital Products Inc. | $154.00 | 7 |
| Calliditas Therapeutics US Inc. | $144.12 | 6 |
What the 2025 payments were for
- Food and Beverage$2,086 · 80 payments
Receiving payments does not imply wrongdoing. What Open Payments covers ·original records
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