Quick answers
- Does Ronald J. Sierzenski accept Medicare assignment?
- Yes. Medicare's clinician data says Ronald J. Sierzenski 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 Ronald J. Sierzenski see?
- In 2024, CMS data shows 118 Original Medicare patients and 173 services for Ronald J. Sierzenski. This counts Original Medicare only and measures volume, not quality.
- What is Ronald J. Sierzenski's NPI number?
- 1861428633. 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 Ronald J. Sierzenski, 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 | 118 |
|---|---|
| Services billed to Medicare | 173 |
| Different services or procedures | 11 |
| Participating Medicare provider | Yes |
| Average age of these patients | 74 |
Most frequent services
- Management of oxygen chamber therapy (99183)46 services
- Emergency department visit with high level of medical decision making (99285)41 services
- Emergency department visit with moderate level of medical decision making (99284)28 services
- Critical care, first 30-74 minutes (99291)26 services
- Routine electrocardiogram (ecg) using at least 12 leads with interpretation and report only (93010)18 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%
- Arthritis54%
- Chronic kidney disease42%
- Diabetes39%
- Ischemic heart disease38%
Hospitals where Ronald J. Sierzenski works
Medicare's Facility Affiliation Data lists Ronald J. Sierzenski 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.
- Chandler Regional Medical CenterChandler, AZ · Acute Care Hospital · Medicare rating: 4 of 5 stars · Emergency services: listed by Medicare · CCN 030036
- Mercy Gilbert Medical CenterGilbert, AZ · Acute Care Hospital · Medicare rating: 5 of 5 stars · Emergency services: listed by Medicare · CCN 030119
Practice locations
Addresses where Ronald J. Sierzenski is enrolled with Medicare (CMS data updated October 2, 2026).
- 1955 W Frye RdChandler, AZ 85224 (480) 728‑3974
Group practices
Medicare enrollment lists Ronald J. Sierzenski as a member of this group (CMS data updated October 2, 2026).
- Valley Hyperbarics LLC6 clinicians in the group
Specialties
- Emergency Medicineprimary
Other emergency medicine doctors in Chandler
Clinicians with the same Medicare primary specialty in Chandler, AZ — not a recommendation.
Other clinicians in Valley Hyperbarics LLC
Medicare enrollment lists these clinicians in the same group practice — not a recommendation.
Clinician information
| Credential | MD |
|---|---|
| Medical school | Jefferson Medical College Of Thomas Jefferson University |
| Graduation year | 1997 (29 years since medical school) |
| Gender (as listed) | Male |
| Medicare assignment | Accepts (Medicare-approved amount as full payment) |
| NPI (National Provider Identifier) | 1861428633 |
| 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