Elmer Y. Chang, MD

Medicare activity in 2024

Official CMS public-use data for Elmer Y. Chang, 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)328 services
2. Biopsy of large bowel using a flexible endoscope (45380)192 services
3. Biopsy of esophagus, stomach, and/or upper small bowel using a flexible endoscope (43239)149 services
4. Established patient office or other outpatient visit with low level od decision making, if using time, 20 minutes or more (99213)149 services
5. Removal of polyps or growths of large bowel using an endoscope with mechanical snare (45385)130 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 cholesterol75%
• High blood pressure66%
• Arthritis53%
• Ischemic heart disease26%
• Anxiety25%
• Osteoporosis23%

Hospitals where Elmer Y. Chang works

Medicare's Facility Affiliation Data lists Elmer Y. Chang 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.

• Hoag Memorial Hospital PresbyterianNewport Beach, CA · Acute Care Hospital · Medicare rating: 5 of 5 stars · Emergency services: listed by Medicare · CCN 050224
• Providence Mission HospitalMission Viejo, CA · Acute Care Hospital · Medicare rating: 5 of 5 stars · Emergency services: listed by Medicare · CCN 050567

Practice locations

Addresses where Elmer Y. Chang is enrolled with Medicare (CMS data updated October 2, 2026).

• 1950 Sunny Crest Dr, Suite 2900Fullerton, CA 92835 (714) 992‑5350
• 27700 Medical Ctr RdMission Viejo, CA 92691 (949) 364‑1400
• 27799 Medical Ctr RdMission Viejo, CA 92691

Group practices

Medicare enrollment lists Elmer Y. Chang as a member of this group (CMS data updated October 2, 2026).

• Providence Medical Foundation1,466 clinicians in the group

Specialties

• Gastroenterologyprimary

Find other Gastroenterology doctors in California →

Other gastroenterologists in Fullerton

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

• Edward J. Block, MD
• Jack C. Feng, MD
• Yee S. Miao, MD
• Wanjun S. Bae, MD
• Daniald M. Rodrigues, MD
• Scott P. Sainburg, MD
• Sajen J. Mathews, MD
• Douglas L. Nguyen, MD

All gastroenterologists in Fullerton →

Other clinicians in Providence Medical Foundation

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

• Hector W. Ho, MD
• Theresa L. Mortensen, NP
• Lea Dominique M. Abadies, PA
• Dmitry A. Leongardt, MD
• Jennifer J. Choate, MD
• Bruce N. Tucker, 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