Quick answers
- Does Christopher T. Grennan accept Medicare assignment?
- Yes. Medicare's clinician data says Christopher T. Grennan accepts Medicare assignment (the Medicare-approved amount as full payment for covered services), as of October 2, 2026. Ask the office to confirm before your visit.
- How many Medicare patients does Christopher T. Grennan see?
- In 2024, CMS data shows 321 Original Medicare patients and 3,833 services for Christopher T. Grennan. This counts Original Medicare only and measures volume, not quality.
- What is Christopher T. Grennan's NPI number?
- 1952620270. The NPI (National Provider Identifier) is the clinician's permanent federal ID; you can look it up in the official NPI Registry.
Medicare activity in 2024
Official CMS public-use data for Christopher T. Grennan, 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.
| Original Medicare patients | 321 |
|---|---|
| Services billed to Medicare | 3,833 |
| Different services or procedures | 71 |
| Participating Medicare provider | Yes |
| Average age of these patients | 74 |
Most frequent services
- Insertion of needle into vein for collection of blood sample (36415)850 services
- Established patient office or other outpatient visit with moderate level of decision making, if using time, 30 minutes or more (99214)511 services
- Established patient office or other outpatient visit with low level od decision making, if using time, 20 minutes or more (99213)365 services
- Annual wellness visit, includes a personalized prevention plan of service (pps), subsequent visit (G0439)226 services
- Chronic care management services, first 20 minutes of clinical staff time directed by health care professional, per calendar month (99490)153 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 pressure69%
- Arthritis32%
- Diabetes26%
- Ischemic heart disease24%
- Chronic kidney disease21%
Hospitals where Christopher T. Grennan works
Medicare's Facility Affiliation Data lists Christopher T. Grennan 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.
- Ascension Via Christi Hospital Manhattan, IncManhattan, KS · Acute Care Hospital · Medicare rating: 4 of 5 stars · Emergency services: listed by Medicare · CCN 170142
- Stormont Vail Health Flint Hills, LLCJunction City, KS · Acute Care Hospital · Medicare rating: 4 of 5 stars · Emergency services: listed by Medicare · CCN 170074
- Stormont Vail HospitalTopeka, KS · Acute Care Hospital · Medicare rating: 4 of 5 stars · Emergency services: listed by Medicare · CCN 170086
- Wamego Health CenterWamego, KS · Critical Access Hospital · Emergency services: listed by Medicare · CCN 171337
Practice locations
Addresses where Christopher T. Grennan is enrolled with Medicare (CMS data updated October 2, 2026).
- 1704 Commercial CirWamego, KS 66547 (785) 456‑2207
Group practices
Medicare enrollment lists Christopher T. Grennan as a member of this group (CMS data updated October 2, 2026).
- Cotton-O'neil Clinic Revocable Trust666 clinicians in the group
Specialties
- Family Practiceprimary
Other family doctors in Kansas
Clinicians with the same Medicare primary specialty in Kansas — not a recommendation.
Other clinicians in Cotton-O'neil Clinic Revocable Trust
Medicare enrollment lists these clinicians in the same group practice — not a recommendation.
Clinician information
| Credential | MD |
|---|---|
| Medical school | University Of Kansas School Of Med (kc/wich/sal) |
| Graduation year | 2010 (16 years since medical school) |
| Gender (as listed) | Male |
| Medicare assignment | Accepts (Medicare-approved amount as full payment) |
| Telehealth | Offers telehealth services |
| NPI (National Provider Identifier) | 1952620270 |
| Corrections | Report an error or suggest an update → |
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
- Facility Affiliation Data — Centers for Medicare & Medicaid Services (CMS), data updated October 2, 2026, retrieved October 29, 2026
- Hospital General Information — CMS, data updated October 26, 2026, retrieved November 13, 2026
- National Downloadable File (Doctors and Clinicians) — CMS, data updated October 2, 2026, retrieved October 29, 2026
- Medicare Physician & Other Practitioners - by Provider — CMS, data year 2024, released May 21, 2026; Medicare Physician & Other Practitioners - by Provider and Service
- NPI Registry — U.S. Department of Health and Human Services (NPPES), the clinician’s official record
- Medicare Care Compare — official Medicare tool to look up clinicians