Quick answers
- Does William J. Zwiers accept Medicare assignment?
- Yes. Medicare's clinician data says William J. Zwiers 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 William J. Zwiers see?
- In 2024, CMS data shows 227 Original Medicare patients and 344 services for William J. Zwiers. This counts Original Medicare only and measures volume, not quality.
- What is William J. Zwiers's NPI number?
- 1013071372. 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 William J. Zwiers, 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 | 227 |
|---|---|
| Services billed to Medicare | 344 |
| Different services or procedures | 25 |
| Participating Medicare provider | Yes |
| Average age of these patients | 72 |
Most frequent services
- Anesthesia for lens surgery (00142)284 services
- Anesthesia for other procedure on eye (00140)20 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 pressure66%
- High cholesterol64%
- Arthritis39%
- Diabetes28%
- Anxiety24%
- Ischemic heart disease19%
Hospitals where William J. Zwiers works
Medicare's Facility Affiliation Data lists William J. Zwiers 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.
- Trinity Health Muskegon HospitalMuskegon, MI · Acute Care Hospital · Medicare rating: 3 of 5 stars · Emergency services: listed by Medicare · CCN 230066
Practice locations
Addresses where William J. Zwiers is enrolled with Medicare (CMS data updated October 2, 2026).
- 200 Jefferson Ave SEGrand Rapids, MI 49503 (734) 263‑2400
- 602 Michigan AveHolland, MI 49423 (616) 392‑5141
- 999 Washington AveHolland, MI 49423 (800) 343‑3588
Group practices
Medicare enrollment lists William J. Zwiers as a member of these groups (CMS data updated October 2, 2026).
- Saint Mary's Health Services173 clinicians in the group
- Macatawa Anesthesia PC24 clinicians in the group
- Fast Asleep Anesthesia Staffing Services LLC2 clinicians in the group
Specialties
Find other clinicians: Certified Registered Nurse Anesthetist (CRNA), Michigan →
Other nurse anesthetists in Grand Rapids
Clinicians with the same Medicare primary specialty in Grand Rapids, MI — not a recommendation.
Other clinicians in Saint Mary's Health Services
Medicare enrollment lists these clinicians in the same group practice — not a recommendation.
Clinician information
| Credential | CNA |
|---|---|
| Graduation year | 2004 |
| Gender (as listed) | Male |
| Medicare assignment | Accepts (Medicare-approved amount as full payment) |
| NPI (National Provider Identifier) | 1013071372 |
| 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