Oscar L. Chien, MD

Medicare activity in 2024

Official CMS public-use data for Oscar L. Chien, 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. Established patient office or other outpatient visit with moderate level of decision making, if using time, 30 minutes or more (99214)2,140 services
2. Subsequent hospital care with moderate levelof medical decision making, if using time, at least 35 minutes (99232)1,199 services
3. Subsequent nursing facility care with high level of medical decision making, per day, if using time, at least 45 minutes (99310)784 services
4. Initial hospital care with moderate level of medical decision making, if using time, at least 75 minutes (99223)155 services
5. Initial nursing facility care with high level of medical decision making, per day, if using time, 50 minutes or more (99306)154 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%
• Chronic kidney disease73%
• Diabetes53%
• Arthritis49%
• Osteoporosis48%

Hospitals where Oscar L. Chien works

Medicare's Facility Affiliation Data lists Oscar L. Chien 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.

• Garfield Medical CenterMonterey Park, CA · Acute Care Hospital · Medicare rating: 1 of 5 stars · Emergency services: listed by Medicare · CCN 050737
• San Gabriel Valley Medical CenterSan Gabriel, CA · Acute Care Hospital · Medicare rating: 4 of 5 stars · Emergency services: listed by Medicare · CCN 050132
• USC Arcadia HospitalArcadia, CA · Acute Care Hospital · Medicare rating: 3 of 5 stars · Emergency services: listed by Medicare · CCN 050238

Practice locations

Addresses where Oscar L. Chien is enrolled with Medicare (CMS data updated October 2, 2026).

• 1448 S San Gabriel BlSan Gabriel, CA 91776
• 1448 S San Gabriel BlvdSan Gabriel, CA 91776 (626) 569‑2888

Specialties

• Internal Medicineprimary
• Geriatric Medicinealso

Find other Internal Medicine doctors in California →

Other internal medicine doctors in San Gabriel

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

• Jennifer C. Chen, MD
• Yu Yao, MD
• Charles W. Lin, MD
• Peter H. Chiu, MD
• Su K. Lee, MD
• Herman Sardjono, MD
• Zhi Zeng, MD
• Tai H. Wu, MD

All internal medicine doctors in San Gabriel →

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