Bryon S. Callahan, MD

Medicare activity in 2024

Official CMS public-use data for Bryon S. Callahan, 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. Emergency department visit with high level of medical decision making (99285)172 services
2. Routine electrocardiogram (ecg) using at least 12 leads with interpretation and report only (93010)121 services
3. Critical care, first 30-74 minutes (99291)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%
• Diabetes54%
• Arthritis50%
• Chronic kidney disease47%
• Ischemic heart disease41%

Hospitals where Bryon S. Callahan works

Medicare's Facility Affiliation Data lists Bryon S. Callahan 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.

• OakBend Medical CenterRichmond, TX · Acute Care Hospital · Medicare rating: 3 of 5 stars · CCN 450330

Practice locations

Addresses where Bryon S. Callahan is enrolled with Medicare (CMS data updated October 2, 2026).

• 1635 N Loop W, Memorial Hermann Emergency PhysiciansHouston, TX 77008 (713) 338‑6565
• 1705 Jackson StRichmond, TX 77469 (281) 341‑3000
• 22003 Southwest FwyRichmond, TX 77469 (281) 341‑3000

Group practices

Medicare enrollment lists Bryon S. Callahan as a member of these groups (CMS data updated October 2, 2026).

• Memorial Hermann Hospital Based Physician Group276 clinicians in the group
• Integrative Emergency Services Physician Group-Houston PLLC217 clinicians in the group

Specialties

• Emergency Medicineprimary

Find other Emergency Medicine doctors in Texas →

Other emergency medicine doctors in Houston

Clinicians with the same Medicare primary specialty in Houston, TX — not a recommendation.

• Deborah Fadowole, MD
• Ofer Z. Faig, MD
• Michelle M. Armada, MD
• Matthew A. Macdonald, MD
• Sarah E. Dendy, MD
• Mathew T. Martinez, MD
• Richina D. Bicette, MD
• Michelle Mowad, MD

All emergency medicine doctors in Houston →

Other clinicians in Memorial Hermann Hospital Based Physician Group

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

• Deborah Fadowole, MD
• Tara R. Zarco, NP
• Aaron Chen, MD
• Matthew A. Macdonald, MD
• Steven Nail, MD
• Luis A. Villarreal, 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