Zachary A. Certa, MD

Medicare activity in 2024

Official CMS public-use data for Zachary A. Certa, 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.

Most frequent services

1. Emergency department visit with moderate level of medical decision making (99284)19 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 cholesterol56%
• Anxiety53%
• Diabetes50%
• Arthritis44%
• Depression38%

Hospitals where Zachary A. Certa works

Medicare's Facility Affiliation Data lists Zachary A. Certa 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.

• Kaiser Foundation Hospital - AntiochAntioch, CA · Acute Care Hospital · Medicare rating: 1 of 5 stars · Emergency services: listed by Medicare · CCN 050760
• Kaiser Foundation Hospital - Walnut CreekWalnut Creek, CA · Acute Care Hospital · Medicare rating: 3 of 5 stars · Emergency services: listed by Medicare · CCN 050072

Practice locations

Addresses where Zachary A. Certa is enrolled with Medicare (CMS data updated October 2, 2026).

• 1425 S Main StWalnut Creek, CA 94596 (925) 295‑4000

Group practices

Medicare enrollment lists Zachary A. Certa as a member of this group (CMS data updated October 2, 2026).

• Permanente Medical Group Inc10,996 clinicians in the group

Specialties

• Emergency Medicineprimary

Find other Emergency Medicine doctors in California →

Other emergency medicine doctors in Walnut Creek

Clinicians with the same Medicare primary specialty in Walnut Creek, CA — not a recommendation.

• Heba Al Rebh, MD
• Song-Yi Lee, MD
• Peter Ackerman, MD
• Sorapat R. Vijitakula, MD
• Yalina Disla, MD
• Nicole Munz, MD
• Wendy Palacios, MD
• Jonathan Srichandra, MD

All emergency medicine doctors in Walnut Creek →

Other clinicians in Permanente Medical Group Inc

Medicare enrollment lists these clinicians in the same group practice — not a recommendation.

• Sammir Sullivan, MD
• Abinaya Srikanthan, MD
• Heather A. Baskind, MD
• Andrew J. Berg, MD
• Lia Bos, MD
• Peter K. Gerritz, MD

Clinician information

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

1. Facility Affiliation Data — Centers for Medicare & Medicaid Services (CMS), data updated October 2, 2026, retrieved October 29, 2026
2. Hospital General Information — CMS, data updated October 26, 2026, retrieved November 13, 2026
3. National Downloadable File (Doctors and Clinicians) — CMS, data updated October 2, 2026, retrieved October 29, 2026
4. Medicare Physician & Other Practitioners - by Provider — CMS, data year 2024, released May 21, 2026; Medicare Physician & Other Practitioners - by Provider and Service
5. NPI Registry — U.S. Department of Health and Human Services (NPPES), the clinician’s official record
6. Medicare Care Compare — official Medicare tool to look up clinicians