Aaron Patrick Fieker, D.O.
NPI 1326268079ActiveIndividual· Internal Medicine, Gastroenterology· Tulsa, OK
Internal Medicine, Gastroenterology (D.O.) in Tulsa, Oklahoma, trained at Oklahoma State University College of Osteopathic Medicine (class of 2005). Their prescriptions cost Medicare Part D more than their services did: $2,021,446 for 1,713 claims, against $113,820 paid for services in 2024. Abbvie Inc. was the largest of 19 companies reporting payments in 2025, $2,108 in all, mostly food and beverage.
Overview
| NPI | 1326268079 |
|---|---|
| Status | Active |
| Entity type | Individual |
| Credential | D.O. |
| Sole proprietor | No |
| NPI issued | Apr 26, 2007 |
| Last updated in NPPES | May 22, 2025 |
| Certified by provider | May 22, 2025 |
Specialties and licenses
| Taxonomy | Code | License | State |
|---|---|---|---|
| Internal Medicine, Gastroenterology Primary | 207RG0100X | 4758 | OK |
Exclusion screening
| List | Result | Details |
|---|---|---|
| HHS-OIG LEIE · Nov 10, 2026 | No match | Checked by NPI and by name + state |
| North Carolina Medicaid · Nov 11, 2026 | No match | — |
| New York OMIG · Nov 11, 2026 | No match | — |
| Ohio Medicaid · Nov 11, 2026 | No match | — |
| Pennsylvania Medicheck · Nov 11, 2026 | No match | — |
| Washington HCA · Nov 11, 2026 | No match | — |
Official OIG search · How matching works ·Bulk check a roster
Medicare
| Enrollment (PECOS) | Enrolled Practitioner - Gastroenterology (OK) |
|---|---|
| Accepts assignment | Yes (participating) |
Medicare services in 2024
| Medicare patients | 665 |
|---|---|
| Services billed | 1,159 across 56 procedure codes |
| Paid by Medicare | $113,820 |
Part D prescriptions in 2024
| Prescriptions (claims) | 1,713 · 2,405 30-day fills |
|---|---|
| Patients | 644 |
| Total drug cost | $2,021,446 |
| Generic share | 73% of claims |
Education and affiliations
| Medical school | Oklahoma State University College of Osteopathic Medicine |
|---|---|
| Graduation year | 2005 |
| Medicare specialty | Gastroenterology |
| Telehealth | Offers telehealth |
Medical groups
- St. John Physicians, Inc.Tulsa, OK · 259 clinicians
- Gastroenterology Specialists, Inc.Tulsa, OK · 23 clinicians
Hospital affiliations
- Ascension St John Broken ArrowBroken Arrow, OK
- Ascension St John Jane PhillipsBartlesville, OK
- Ascension St John Medical CenterTulsa, OK
- Saint Francis Hospital South, LLCTulsa, OK
- Saint Francis Hospital, IncTulsa, OK
Industry payments (Open Payments)
- 2025$2,108 · 112 payments from 19 companies
- 2024$1,841 · 104 payments from 19 companies
Top paying companies in 2025
| Company | Amount | Payments |
|---|---|---|
| Abbvie Inc. | $530.22 | 36 |
| Pfizer Inc. | $260.42 | 13 |
| Janssen Biotech, Inc. | $258.17 | 13 |
| Takeda Pharmaceuticals U.S.A., Inc. | $245.55 | 10 |
| Madrigal Pharmaceuticals | $152.26 | 5 |
What the 2025 payments were for
- Food and Beverage$2,108 · 112 payments
Receiving payments does not imply wrongdoing. What Open Payments covers ·original records
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All Internal Medicine, Gastroenterology providers in Oklahoma →