Abigail Nisan, MD

Medicare activity in 2024

Official CMS public-use data for Abigail Nisan, 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. Initial hospital care with moderate level of medical decision making, if using time, at least 75 minutes (99223)198 services
2. Subsequent hospital care with moderate levelof medical decision making, if using time, at least 50 minutes (99233)125 services
3. Subsequent hospital care with moderate levelof medical decision making, if using time, at least 35 minutes (99232)63 services
4. Hospital discharge day management, more than 30 minutes (99239)51 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%
• Arthritis57%
• Ischemic heart disease52%
• Heart failure52%
• Diabetes48%

Hospitals where Abigail Nisan works

Medicare's Facility Affiliation Data lists Abigail Nisan 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.

• Heart of Texas Memorial HospitalBrady, TX · Critical Access Hospital · Emergency services: listed by Medicare · CCN 451348
• Shannon Medical CenterSan Angelo, TX · Acute Care Hospital · Medicare rating: 3 of 5 stars · Emergency services: listed by Medicare · CCN 450571

Practice locations

Addresses where Abigail Nisan is enrolled with Medicare (CMS data updated October 2, 2026).

• 120 E Beauregard AveSan Angelo, TX 76903 (325) 747‑1511
• 120 E Harris AveSan Angelo, TX 76903 (325) 747‑6741
• 1601 W 11th PlBig Spring, TX 79720 (432) 268‑4880

Group practices

Medicare enrollment lists Abigail Nisan as a member of this group (CMS data updated October 2, 2026).

• Shannon Clinic559 clinicians in the group

Specialties

• Internal Medicineprimary

Find other Internal Medicine doctors in Texas →

Other internal medicine doctors in San Angelo

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

• Antoine Ghaby, DO
• Moulali Shaik
• Vicente Lam Siu, MD
• Randall Slimak, MD
• Sharlet G. Slough, DO
• Kristen L. Treger, MD
• Tamara B. Noack, MD
• Gopimohan Das, MD

All internal medicine doctors in San Angelo →

Other clinicians in Shannon Clinic

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

• Taylor L. Mitchon, PA
• Evamariquitbeniga Abarquez, NP
• David Vance, MD
• Regina J. Garcia, NP
• Moulali Shaik
• Robert Alaly, 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