Warren Chang, MD
Nephrology · Daly City, CANPI 1083674550
Payments from drug & device makers
Across 283 payments — averaging $23.13 each. Meals, travel, consulting and speaking fees, gifts and royalties reported by drug and device makers.
- AstraZeneca$1K
- Amgen$845
- Otsuka America Pharmaceutical, Inc.$492
- Mallinckrodt Hospital Products Inc.$478
- Novo Nordisk$414
- Novartis$347
- plus $3K from 22 others
What the payments were for
- Food & beverage$6,48699%
- Education$591%
Most of this is food and beverage — typically meals provided during product presentations at a clinic or hospital. Nationally that is the single largest category of reported payments by count.
General payments by program year
Who reported the general payments
Companies are grouped under their corporate parent — a single manufacturer often files under several CMS reporting entities. Research and ownership payments are counted separately and are not in this table.
| Company | Payments | Total |
|---|---|---|
| AstraZeneca | 62 | $1,373 |
| Amgen(2 entities) | 32 | $845 |
| Otsuka America Pharmaceutical, Inc. | 22 | $492 |
| Mallinckrodt Hospital Products Inc. | 20 | $478 |
| Novo Nordisk | 20 | $414 |
| Novartis | 12 | $347 |
| Bayer | 15 | $325 |
| Vifor Pharma, Inc. | 23 | $301 |
| Fresenius USA Marketing, Inc. | 16 | $288 |
| Calliditas Therapeutics US Inc. | 12 | $274 |
| Johnson & Johnson | 8 | $261 |
| Otsuka Pharmaceutical Development & Commercialization, Inc. | 6 | $158 |
| Vantive US Healthcare LLC | 1 | $141 |
| Travere Therapeutics, Inc. | 5 | $141 |
| Aurinia Pharma U.S., Inc. | 4 | $108 |
| Ardelyx, Inc. | 4 | $102 |
| ANI Pharmaceuticals, Inc. | 3 | $97 |
| Boehringer Ingelheim | 4 | $92 |
| OPKO Pharmaceuticals, LLC | 3 | $59 |
| Lilly USA, LLC | 2 | $49 |
| Takeda Pharmaceuticals U.S.A., Inc. | 2 | $42 |
| Abiomed | 1 | $31 |
| Scpharmaceuticals Inc. | 1 | $30 |
| Akebia Therapeutics Inc | 1 | $28 |
| CMP Pharma, Inc. | 1 | $23 |
| Apellis Pharmaceuticals, Inc. | 1 | $18 |
| Harrow Eye, LLC | 1 | $14 |
| Daiichi Sankyo Inc. | 1 | $13 |
What the payments were tied to
Products named in the reported payments. Only payments of $100 or more are attributed here — the typical reported payment nationally is a meal worth about $16, and listing those product-by-product would be noise.
How this compares
$6,545 in reported general payments places this provider in the 70th percentile of 1,341 nephrology providers in California.
Medicare billing
What this is not: this is the amount Original Medicare Part B allowed for services this provider billed in 2024. It is not their income. It excludes Medicare Advantage — now more than half of all Medicare enrollment — along with Medicaid and all commercial insurance, and it is gross practice revenue before staff, rent, supplies and malpractice premiums. CMS also suppresses any figure covering ten or fewer patients, so low-volume providers appear smaller than they are.
Most prescribed under Part D
| Drug | Claims | Cost to plans & patients |
|---|---|---|
| FarxigaDapagliflozin Propanediol | 188 | $187,292 |
| VelphoroSucroferric Oxyhydroxide | 16 | $51,041 |
| LokelmaSodium Zirconium Cyclosilicate | 37 | $40,567 |
| JardianceEmpagliflozin | 28 | $35,294 |
| EliquisApixaban | 16 | $20,715 |
| VeltassaPatiromer Calcium Sorbitex | 19 | $15,593 |
| KerendiaFinerenone | 13 | $14,508 |
| DapagliflozinDapagliflozin Propanediol | 22 | $12,449 |
| ProsolParenteral Amino Acid 20% No.1 | 86 | $11,859 |
| Sevelamer Carbonate | 35 | $9,595 |
| Cinacalcet Hcl | 31 | $7,155 |
| Midodrine Hcl | 26 | $6,086 |
| Hydralazine Hcl | 177 | $2,909 |
| Labetalol Hcl | 56 | $2,630 |
| Sodium Polystyrene Sulfonate | 23 | $2,050 |
Paid to pharmacies, not to this prescriber.
Companies that both paid and supply prescribed drugs
These companies both reported payments to this provider and make drugs the provider prescribed under Medicare Part D in 2024. For most specialties this overlap is expected — a cardiologist who is paid by a cardiology drugmaker also treats heart disease. It is shown so the reader can see it, not because it implies anything on its own.
| Company | Paid to this provider | Part D cost of their drugs |
|---|---|---|
| AstraZenecaFarxiga, Lokelma | $1,373 | $227,859225 claims |
| Fresenius USA Marketing, Inc.Velphoro | $288 | $51,04116 claims |
| Boehringer IngelheimJardiance | $92 | $35,29428 claims |
| BayerKerendia | $325 | $14,50813 claims |
| ANI Pharmaceuticals, Inc.Valsartan | $97 | $56021 claims |
Reading this fairly. The Part D column is what drug plans and patients paid pharmacies — this provider received none of it, and it reflects how many patients they treat and what those drugs cost. Against peers, this provider's reported payments sit in the 70th percentile of 1,341 nephrology providers in California.
Other nephrology in Daly City
- Anjay RastogiLos Angeles$6.3M
- Aamir JamalSan Dimas$5.5M
- Mohamed El-ShahawyLos Angeles$4.4M
- Kalpesh PatelCalabasas$3.6M
- Jehad HaggiagiMission Hills$3.6M
- Malvin YanSouth Gate$3.3M
- Sohan DuaNorthridge$3.2M
- Richard LafayetteStanford$3M
- Anant DesaiGranada Hills$2.9M
- Glenn ChertowStanford$2.2M
Where these figures come from
- Payments: CMS Open Payments, program years 2019–2025 (publication P06302026_06032026).
- Billing: Medicare Physician & Other Practitioners, data year 2024. Original Medicare Part B only.
- Identity: NPPES NPI Registry, July 2026.