John Chang, MD
NPI 1598704827 · Anesthesiology Physician · Mission Viejo, CA
Enrolled with Medicare as Practitioner - Anesthesiology · source: CMS PECOS Public Provider Enrollment (2026.04.01)
John Chang, MD is a Anesthesiology Physician provider in Mission Viejo, CA (NPI 1598704827).
Provider details
- NPI number
- 1598704827
- Entity type
- Individual
- Primary specialty
- Anesthesiology PhysicianAllopathic & Osteopathic Physicians
- Credential
- MD
- Sex
- Male
- Sole proprietor
- No
- License
- A65638 (CA)
Specialties & taxonomies
Allopathic & Osteopathic Physicians
Profile Score
A profile completeness & documented-activity index — NOT a quality, outcomes, or patient-satisfaction rating.
- Registry tenure25% of score
20 yrs in NPPES registry
- Profile completeness25% of score
100% of core fields populated
- Practice footprint15% of score
1 documented practice location
- Medicare service volume (vs. specialty peers)25% of score
238 Medicare services, 2024 (ranked within specialty)
- Open Payments transparency10% of score
Has Open Payments disclosures (2024)
Medicare volume is ranked against active providers in the same specialty. Signals a provider has no public data for (e.g. Medicare claims) are left out of the score entirely — never counted as zero — so providers without that data are not penalized. See the full formula and weights in our .
What this provider does (Medicare)
Based on Medicare fee-for-service claims, 2024; not all care is captured.
| Service (HCPCS) | Medicare services | Typical Medicare-allowed (2024) |
|---|---|---|
| Anesthesia for Lens Surgery00142 | 115 | $126 |
| Anesthesia for Procedure on Small and Large Bowel Using an Endoscope00813 | 37 | $166 |
| Anesthesia for Procedure on Eyelid00103 | 33 | $204 |
| Anesthesia for Other Procedure on Large Bowel Using an Endoscope00811 | 22 | $130 |
| Anesthesia for Other Procedure on Esophagus, Stomach, Or Upper Small Bowel Using an Endoscope00731 | 19 | $133 |
| Anesthesia for Exam of Colon Using an Endoscope00812 | 12 | $108 |
Typical Medicare-allowed amounts for these services range $108–$204 (2024). The Medicare-allowed amount is what Medicare recognizes for a service under fee-for-service — a reference figure for 2024, and not what you would be billed. Medicare Part B covers roughly an eighth of all NPIs (65+ skew); services with fewer than 11 beneficiaries are suppressed by CMS. Source: CMS Medicare Physician & Other Practitioners, by Provider & Service.
Transparency — industry payments
Based on CMS Open Payments, 2024; not all care is captured.
$619 across 2 records (Open Payments 2024)
Open Payments discloses payments and transfers of value (meals, travel, consulting, research, royalties) from drug and device makers to providers. This is a transparency signal, not a verdict — such payments are legal and common, and their presence is neither an endorsement nor a criticism. Source: CMS Open Payments, program year 2024.
Practice location
Mailing address
Registry dates
- Enumerated
- 2006-06-05
- Last updated
- 2010-02-12
Frequently asked questions
- What is John Chang's NPI number?
- John Chang's National Provider Identifier (NPI) is 1598704827, a unique 10-digit ID issued by CMS for use in standard healthcare transactions.
- What is John Chang's specialty?
- John Chang is listed in the NPPES registry with a primary specialty of Anesthesiology Physician (Allopathic & Osteopathic Physicians).
- Where is John Chang located?
- John Chang's practice location on file with NPPES is 27401 Los Altos, Mission Viejo, CA 92691-6316.
- What is John Chang's phone number?
- The practice phone number listed in the NPPES registry for John Chang is (949) 582-9624.
- Does John Chang accept Medicare?
- John Chang is approved to bill Medicare according to CMS PECOS enrollment data (2026.04.01). Confirm current participation with the provider before scheduling.
- Is John Chang's NPI active?
- Yes — John Chang's NPI (1598704827) is active in the NPPES registry as of the last update on 2010-02-12.
Source: CMS NPPES Data Dissemination (June 2026). NPI Central is not affiliated with CMS. Data is provided as-is from the public registry.