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Compare the published Medicare service mix of Keith G Zacher, MD with clinicians in the same registry specialty: Surgery.

PHOENIX, AZ · Exact areaEdit location

2024 published service data · 83 eligible profiles compared. Similarity describes billing patterns, not quality, outcomes, or suitability for your care.

Kara Villareal, M.D.

Surgery · Phoenix, AZ

Shared published services
2 shared services · view billing descriptions
  • Initial hospital care with straightforward or low-level medical decision making, if using time, at least 55 minutes (99222)
  • Removal of gallbladder using an endoscope (47562)
61%Service-mix similarityView profile →

Paola G Pieri, MD

Surgery · Phoenix, AZ

Shared published services
1 shared services · view billing descriptions
  • Initial hospital care with straightforward or low-level medical decision making, if using time, at least 55 minutes (99222)
56%Service-mix similarityView profile →

Erin Kloos, M.D.

Surgery · Phoenix, AZ

Shared published services
2 shared services · view billing descriptions
  • Initial hospital care with straightforward or low-level medical decision making, if using time, at least 55 minutes (99222)
  • Removal of gallbladder using an endoscope (47562)
53%Service-mix similarityView profile →

Christopher Knapp, MD

Surgery · Phoenix, AZ

Shared published services
1 shared services · view billing descriptions
  • Initial hospital care with straightforward or low-level medical decision making, if using time, at least 55 minutes (99222)
51%Service-mix similarityView profile →

Grant Andrew Huish, DO

Surgery · Phoenix, AZ

Shared published services
2 shared services · view billing descriptions
  • Initial hospital care with straightforward or low-level medical decision making, if using time, at least 55 minutes (99222)
  • Removal of gallbladder using an endoscope (47562)
45%Service-mix similarityView profile →

Brad Allen Olberding, MD

Surgery · Phoenix, AZ

Shared published services
2 shared services · view billing descriptions
  • Initial hospital care with straightforward or low-level medical decision making, if using time, at least 55 minutes (99222)
  • Removal of gallbladder using an endoscope (47562)
44%Service-mix similarityView profile →

Lora Anna Shirey, MD

Surgery · Phoenix, AZ

Shared published services
1 shared services · view billing descriptions
  • Initial hospital care with straightforward or low-level medical decision making, if using time, at least 55 minutes (99222)
41%Service-mix similarityView profile →

Steven Cary Simon, MD

Surgery · Phoenix, AZ

Shared published services
1 shared services · view billing descriptions
  • Initial hospital care with straightforward or low-level medical decision making, if using time, at least 55 minutes (99222)
41%Service-mix similarityView profile →

G. Paul Dabrowski, MD

Surgery · Phoenix, AZ

Shared published services
1 shared services · view billing descriptions
  • Initial hospital care with straightforward or low-level medical decision making, if using time, at least 55 minutes (99222)
39%Service-mix similarityView profile →

Kei Nagatomo, D.O.

Surgery · Phoenix, AZ

Shared published services
1 shared services · view billing descriptions
  • Initial hospital care with straightforward or low-level medical decision making, if using time, at least 55 minutes (99222)
39%Service-mix similarityView profile →

Varun Chakravorty, M.D.

Surgery · Phoenix, AZ

Shared published services
1 shared services · view billing descriptions
  • Initial hospital care with straightforward or low-level medical decision making, if using time, at least 55 minutes (99222)
38%Service-mix similarityView profile →

Scott J Hillmann, M.D.

Surgery · Phoenix, AZ

Shared published services
1 shared services · view billing descriptions
  • Initial hospital care with straightforward or low-level medical decision making, if using time, at least 55 minutes (99222)
36%Service-mix similarityView profile →
How this comparison works

We use the same calendar year of CMS Medicare Physician & Other Practitioners data for both providers. Published non-drug service counts are combined by HCPCS code across places of service. We apply log(1 + count), normalize the vectors, and compare them using cosine similarity.

Candidates share the reference provider’s current NPPES primary taxonomy and match the location you enter. We examine up to 500 candidates in NPI order, then show up to 12 with the highest positive similarity within that set. The score is not a percentile, medical recommendation, or prediction. Suppressed services are not estimated. Medicare fee-for-service data does not describe a provider’s entire practice.

Source: CMS Medicare Physician & Other Practitioners - by Provider and Service : 2024-12-01 · Published May 21, 2026.