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Compare the published Medicare service mix of Karen Antwiler, M.D. with clinicians in the same registry specialty: Addiction Medicine · Family Practice (CMS).

CA · Exact areaEdit location

2024 published service data · 28 eligible profiles compared. Similarity describes billing patterns, not quality, outcomes, or suitability for your care.

Robert William Watrous, MD

Addiction Medicine · Internal Medicine (CMS) · San Bernardino, CA

Shared published services
3 shared services · view billing descriptions
  • Subsequent hospital care with moderate levelof medical decision making, if using time, at least 50 minutes (99233)
  • Initial hospital care with moderate level of medical decision making, if using time, at least 75 minutes (99223)
  • Subsequent hospital care with moderate levelof medical decision making, if using time, at least 35 minutes (99232)
61%Service-mix similarityView profile →

Zachary Michael Zwolak, D.O.

Addiction Medicine · Family Practice (CMS) · Ventura, CA

Shared published services
3 shared services · view billing descriptions
  • Established patient office or other outpatient visit with moderate level of decision making, if using time, 30 minutes or more (99214)
  • Subsequent hospital care with moderate levelof medical decision making, if using time, at least 50 minutes (99233)
  • Initial hospital care with moderate level of medical decision making, if using time, at least 75 minutes (99223)
61%Service-mix similarityView profile →

Tipu Vahid Khan, M.D.

Addiction Medicine · Family Practice (CMS) · Ventura, CA

Shared published services
3 shared services · view billing descriptions
  • Established patient office or other outpatient visit with moderate level of decision making, if using time, 30 minutes or more (99214)
  • Subsequent hospital care with moderate levelof medical decision making, if using time, at least 50 minutes (99233)
  • Initial hospital care with moderate level of medical decision making, if using time, at least 75 minutes (99223)
59%Service-mix similarityView profile →

Fred John Vonstieff, M.D.

Addiction Medicine · Internal Medicine (CMS) · Concord, CA

Shared published services
3 shared services · view billing descriptions
  • Subsequent hospital care with moderate levelof medical decision making, if using time, at least 50 minutes (99233)
  • Initial hospital care with moderate level of medical decision making, if using time, at least 75 minutes (99223)
  • Subsequent hospital care with moderate levelof medical decision making, if using time, at least 35 minutes (99232)
50%Service-mix similarityView profile →

Tamer Rezk, MD

Addiction Medicine (CMS) · Whittier, CA

Shared published services
3 shared services · view billing descriptions
  • Established patient office or other outpatient visit with moderate level of decision making, if using time, 30 minutes or more (99214)
  • Subsequent hospital care with moderate levelof medical decision making, if using time, at least 35 minutes (99232)
  • Initial hospital care with straightforward or low-level medical decision making, if using time, at least 55 minutes (99222)
49%Service-mix similarityView profile →

Sandeep Singh Mann, MD

Addiction Medicine · Family Practice (CMS) · Stockton, CA

Shared published services
2 shared services · view billing descriptions
  • Subsequent hospital care with moderate levelof medical decision making, if using time, at least 50 minutes (99233)
  • Initial hospital care with moderate level of medical decision making, if using time, at least 75 minutes (99223)
49%Service-mix similarityView profile →

Noelle Griffin Martinez, MD MPH

Specialty details in registry · San Francisco, CA

Shared published services
2 shared services · view billing descriptions
  • Subsequent hospital care with moderate levelof medical decision making, if using time, at least 50 minutes (99233)
  • Subsequent hospital care with moderate levelof medical decision making, if using time, at least 35 minutes (99232)
48%Service-mix similarityView profile →

Joy Hao, MD

Internal Medicine (CMS) · Santa Monica, CA

Shared published services
1 shared services · view billing descriptions
  • Established patient office or other outpatient visit with moderate level of decision making, if using time, 30 minutes or more (99214)
48%Service-mix similarityView profile →

Steven R Ey, M.D.

Addiction Medicine · Family Practice (CMS) · Newport Beach, CA

Shared published services
2 shared services · view billing descriptions
  • Initial hospital care with moderate level of medical decision making, if using time, at least 75 minutes (99223)
  • Subsequent hospital care with moderate levelof medical decision making, if using time, at least 35 minutes (99232)
37%Service-mix similarityView profile →

Matthew Lamon, DO

Family Practice (CMS) · Ventura, CA

Shared published services
1 shared services · view billing descriptions
  • Established patient office or other outpatient visit with moderate level of decision making, if using time, 30 minutes or more (99214)
35%Service-mix similarityView profile →

Stephen Peter Bradley, MD

Addiction Medicine · Family Practice (CMS) · Lakeport, CA

Shared published services
2 shared services · view billing descriptions
  • Established patient office or other outpatient visit with moderate level of decision making, if using time, 30 minutes or more (99214)
  • Testing for presence of drug, read by direct observation (80305)
33%Service-mix similarityView profile →

Hamed Haghnazar, MD, MPH

Addiction Medicine · Family Practice (CMS) · Tarzana, CA

Shared published services
1 shared services · view billing descriptions
  • Initial hospital care with moderate level of medical decision making, if using time, at least 75 minutes (99223)
31%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.