Siena Elisa Ona, MD

Medicare activity in 2024

Official CMS public-use data for Siena Elisa Ona, data year 2024 (released May 21, 2026). It covers Original Medicare (fee-for-service) patients only, not Medicare Advantage or other insurance. It shows volume, not quality or outcomes. CMS hides any count of 10 or fewer patients.

Most frequent services

1. Subsequent hospital care with moderate levelof medical decision making, if using time, at least 35 minutes (99232)913 services
2. Subsequent hospital care with moderate levelof medical decision making, if using time, at least 50 minutes (99233)328 services
3. Initial hospital care with moderate level of medical decision making, if using time, at least 75 minutes (99223)65 services
4. Subsequent hospital care with straightforward or low level of medical decision making, per day, if using time, at least 25 minutes (99231)36 services

Chronic conditions among these patients

Share of this clinician’s Original Medicare patients with each condition, as published by CMS (it describes the patients, not the care given).

• High blood pressure75%
• High cholesterol75%
• Diabetes75%
• Heart failure75%
• Chronic kidney disease66%
• Arthritis63%

Hospitals where Siena Elisa Ona works

Medicare's Facility Affiliation Data lists Siena Elisa Ona at these hospitals (updated October 2, 2026). Each hospital page shows its address, phone, emergency services, Medicare rating and all its clinicians. Star rating and emergency services: Hospital General Information (CMS), data updated October 26, 2026.

• Memorialcare Long Beach Medical CenterLong Beach, CA · Acute Care Hospital · Medicare rating: 2 of 5 stars · Emergency services: not listed by Medicare · CCN 050485

Practice locations

Addresses where Siena Elisa Ona is enrolled with Medicare (CMS data updated October 2, 2026).

• 101 E Valencia Mesa DrFullerton, CA 92835 (714) 771‑8000
• 875 N Brea BlvdBrea, CA 92821 (714) 596‑4288
• 9500 Bolsa Ave, Suite PWestminster, CA 92683 (714) 395‑4648

Group practices

Medicare enrollment lists Siena Elisa Ona as a member of this group (CMS data updated October 2, 2026).

• Dieumy Michelle Thai M D Inc4 clinicians in the group

Specialties

• Physical Medicine and Rehabilitationprimary

Find other Physical Medicine and Rehabilitation doctors in California →

Other rehabilitation doctors in Fullerton

Clinicians with the same Medicare primary specialty in Fullerton, CA — not a recommendation.

• Robyn K. Sato, DO
• Dieumy M. Thai, MD
• Lisa Pitino
• Kenneth S. Rodrigues, MD
• Gigi P. Thomas, MD
• Amirpasha Ehsan, MD
• Jerry S. Chuang, MD
• Theodora K. Wong, MD

All rehabilitation doctors in Fullerton →

Other clinicians in Dieumy Michelle Thai M D Inc

Medicare enrollment lists these clinicians in the same group practice — not a recommendation.

• Dieumy M. Thai, MD
• Kim D. Thai, MD

Clinician information

Most corrections must be made at the source: clinicians update their NPI Registry record (NPPES) and their Medicare enrollment (PECOS); this page follows the next data release.

Sources

1. Facility Affiliation Data — Centers for Medicare & Medicaid Services (CMS), data updated October 2, 2026, retrieved October 29, 2026
2. Hospital General Information — CMS, data updated October 26, 2026, retrieved November 13, 2026
3. National Downloadable File (Doctors and Clinicians) — CMS, data updated October 2, 2026, retrieved October 29, 2026
4. Medicare Physician & Other Practitioners - by Provider — CMS, data year 2024, released May 21, 2026; Medicare Physician & Other Practitioners - by Provider and Service
5. NPI Registry — U.S. Department of Health and Human Services (NPPES), the clinician’s official record
6. Medicare Care Compare — official Medicare tool to look up clinicians