Onechang W. Lee, MD

Medicare activity in 2024

Official CMS public-use data for Onechang W. Lee, 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 50 minutes (99233)106 services
2. Initial hospital care with straightforward or low-level medical decision making, if using time, at least 55 minutes (99222)94 services
3. Critical care, first 30-74 minutes (99291)90 services
4. Established patient office or other outpatient visit with moderate level of decision making, if using time, 30 minutes or more (99214)37 services
5. New patient office or other outpatient visit with moderate level of medical decision making, if using time, 45 minutes or more (99204)21 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%
• Arthritis71%
• Stroke or mini-stroke57%
• Diabetes52%
• Chronic kidney disease46%

Hospitals where Onechang W. Lee works

Medicare's Facility Affiliation Data lists Onechang W. Lee 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 Orange Coast Medical CenterFountain Valley, CA · Acute Care Hospital · Medicare rating: 4 of 5 stars · Emergency services: listed by Medicare · CCN 050678
• Orange County Global Medical CenterSanta Ana, CA · Acute Care Hospital · Medicare rating: 2 of 5 stars · Emergency services: listed by Medicare · CCN 050746
• UCI Health-OrangeOrange, CA · Acute Care Hospital · Medicare rating: 4 of 5 stars · Emergency services: listed by Medicare · CCN 050348

Practice locations

Addresses where Onechang W. Lee is enrolled with Medicare (CMS data updated October 2, 2026).

• 18035 Brookhurst St, Suite 1700Fountain Valley, CA 92708 (714) 433‑2000

Group practices

Medicare enrollment lists Onechang W. Lee as a member of this group (CMS data updated October 2, 2026).

• Tien T Nguyen M.D. Inc.6 clinicians in the group

Specialties

• Neurosurgeryprimary

Find other Neurosurgery doctors in California →

Other neurosurgeons in California

Clinicians with the same Medicare primary specialty in California — not a recommendation.

• Devin K. Binder, MD
• Tien T. Nguyen, MD
• Rollin Hu, MD
• Diane Aum, MD
• Promod Pillai, MD
• Conor W. Grady, MD
• Benjamin J. Serxner, MD
• Olawale Sulaiman, MD

All neurosurgeons in California →

Other clinicians in Tien T Nguyen M.D. Inc.

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

• Li S. Zeng, PA
• Tien T. Nguyen, MD
• Wan Ling Low, PA
• Robert Phan, PA

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