Ryan K Ah San, PA-C

Medicare patients and services, 2024

From the CMS Medicare Physician & Other Practitioners file for calendar year 2024. It counts Original Medicare patients only, so a practice that mostly sees Medicare Advantage or privately insured patients looks smaller here than it is.

Dollar amounts are not shown. What Medicare pays a practice is gross billings, before staff, premises and tax and including the cost of any drugs it administers, so it is not what a clinician earns.

Payments from drug and device companies, 2025

Drug and device makers are required by federal law (the Physician Payments Sunshine Act) to report what they pay or give to clinicians, and CMS publishes the reports as Open Payments. This is the 2025 program year. A report is a record of a payment, not an allegation of anything, and many are small items such as meals. Only general payments are listed here; research payments and ownership or investment interests are reported separately by CMS and are not shown.

Each amount is the sum of what companies reported for that kind of payment in 2025, rounded to the dollar. Not all of it is income to the clinician: a meal is not a fee, a charitable contribution goes to a charity, and a royalty or an acquisition payment is not a salary.

Check a report, or dispute one, at the source in CMS’s own tool, Open Payments. Corrections go through CMS’s dispute process. This site removes a home address on request and asks for no proof, because that is privacy; it will not remove an accurate payment report on request, because that is a statutory public disclosure.

Practises at

Facilities the CMS Facility Affiliation file lists for this clinician.

• Memorialcare Saddleback Medical Center Hospital · Laguna Hills, CA · listed as Saddleback Memorial Medical Center

Colleagues at Memorialcare Medical Foundation

Clinicians the CMS Doctors & Clinicians file lists under the same group practice. CMS counts 562 clinicians in the practice; 12 are shown here.

• Jon G Biorkman, MD Family Medicine Physician · Irvine, CA
• Miss. Lisa Renee Crane, MD Obstetrics Physician · Irvine, CA
• Mario Curti, MD Hematology & Oncology Physician · Los Alamitos, CA
• Kien-An Duong, MD Internal Medicine Physician · Laguna Woods, CA
• Dr. Alexander Hu, DO Family Medicine Physician · Beverly Hills, CA
• MS. Nancy Jean McGinn, RN, MSN, FNP-BC Registered Nurse · Irvine, CA
• Sheila Phuong Nguyen, MD Pediatrics Physician · Fountain Valley, CA
• Dr. Vina Nguyen, MD Hospitalist Physician · Fountain Valley, CA
• Jessica Nicole Santos, PA Physician Assistant · Costa Mesa, CA
• Dr. John H Stasiewicz, MD Family Medicine Physician · Irvine, CA
• Dr. Jamison Ryan Thompson, DO Family Medicine Physician · Cypress, CA
• Vamsi Vemireddy Internal Medicine Physician · Fountain Valley, CA

Other providers in Rancho Santa Margarita

• Tri Colin Cong Tran, PA-C

  Individual Medical Physician Assistant · NPI 1427447713

  29472 Avenida De Las Banderas, Rancho Santa Margarita, CA 92688 · (949) 459-9968

• Barbara Witowska, MSPAC

  Individual Medical Physician Assistant · NPI 1013034230

  22032 El Paseo Ste 130, Rancho Santa Margarita, CA 92688-3947 · (949) 589-9112