Dr. William Chang, MD
What this data tells you about Dr. Chang
Dr. William Chang is a pulmonary disease specialist in Monterey Park, CA, with 11 years of NPI registration. Based on federal Medicare data, Dr. Chang performed 4,577 Medicare services across 1,813 unique beneficiaries.
Between the years covered by Open Payments, Dr. Chang received a total of $4,852 from 22 pharmaceutical and/or device companies across 163 individual payments. These payments are legal, publicly disclosed under the federal Sunshine Act, and common in pulmonary disease. Most payments are for meals and travel — low-value interactions common across virtually all practicing physicians. Patients may wish to discuss these relationships with their provider.
The Data Coverage level for Dr. Chang is Very High — reflecting how much public federal data is available about this provider. Patients are encouraged to use this data as one of several factors when choosing a healthcare provider.
Medicare Practice Summary
Medicare Utilization ↗Top procedures by volume
Ranked by number of services performed for Medicare patients. Avg. submitted charge is what the provider billed; avg. Medicare payment is what CMS paid.
| Procedure | Volume | Avg. paid | Avg. submitted |
|---|---|---|---|
| Hospital follow-up visit, high complexity Subsequent hospital inpatient or observation care for an existing patient involving high-level medical decision making, with at least 50 minutes total time on the date of the encounter. |
2,408 | $99 | $283 |
| Critical care, first 30-74 min Emergency medical care for a critically ill or injured patient lasting between 30 and 74 minutes. This service involves direct patient care and medical decision making to stabilize the patient. |
897 | $176 | $598 |
| Office visit, established patient (30-39 min) A follow-up office visit for an existing patient lasting between 30 and 39 minutes. The visit involves medical evaluation and management of the patient's condition. |
353 | $100 | $304 |
| Hospital follow-up visit, moderate complexity Follow-up hospital visit for an existing patient involving moderate medical decision making. The visit requires at least 35 minutes of time spent on the date of service. |
262 | $66 | $195 |
| Initial hospital admission, high complexity Initial hospital inpatient or observation care for a new patient involving high-level medical decision making, with at least 75 minutes total time on the date of the encounter. |
225 | $144 | $548 |
| Spirometry test before and after medication A test that measures the amount of air you can exhale and the speed of your breathing before and after taking a medication. |
69 | $34 | $250 |
| Lung volume test using gas dilution or washout A test that measures the amount of air in your lungs by using a gas dilution or washout method. |
69 | $40 | $130 |
| Pulmonary gas exchange test A test to examine how well the lungs exchange gases. |
69 | $52 | $140 |
| New patient office visit (45-59 min) An initial office visit for a new patient lasting between 45 and 59 minutes. This code covers the total time spent by the physician or qualified healthcare professional on the date of the encounter. |
45 | $120 | $453 |
| Ultrasound guidance for blood vessel access Use of ultrasound imaging to help locate and access a blood vessel. This guidance assists healthcare providers in performing procedures such as inserting IV lines or drawing blood. |
35 | $12 | $40 |
| Insertion of non-tunneled central venous catheter A procedure to place a central venous catheter for infusion in patients aged 5 years or older. The catheter is inserted directly into a large vein without being tunneled under the skin. |
32 | $69 | $245 |
| Breathing device use evaluation An assessment of how a patient uses a breathing device. The provider reviews the patient's technique and device handling. |
30 | $15 | $50 |
| Smoking cessation counseling, 4-10 minutes A brief counseling session focused on helping patients quit smoking and tobacco use. The provider spends 4 to 10 minutes discussing strategies and support for cessation. |
21 | $16 | $41 |
| Chest fluid aspiration with imaging guidance This procedure involves removing fluid from the chest cavity using imaging technology to guide the needle placement. |
20 | $88 | $306 |
| Additional 30 minutes of critical care This code represents an additional 30 minutes of critical care services provided beyond the initial critical care time period. |
17 | $89 | $300 |
| Exercise-induced lung stress test A test performed to evaluate how the lungs function during physical exertion. It helps identify breathing difficulties or lung conditions that occur specifically when exercising. |
13 | $17 | $195 |
| Emergent tracheostomy An emergency procedure to create an opening in the windpipe to insert a breathing tube, guided by an endoscope. |
12 | $115 | $380 |
Industry Payment Transparency
Open Payments through 2024 ↗Payment profile
Industry payments classified by relationship type. Not all payments are equal — research and consulting reflect different relationships than speaking programs or meals.
Payment trend by year
Annual totals from pharmaceutical and medical device companies.
Payments by company (2024)
All-time payments by company (2019-2024) ›
Associated products mentioned in payments ›
Most payments (100%) are for meals and travel — low-value interactions that are common across virtually all practicing physicians.
Geographic Context
0.0 mi
Data Sources
| Provider Registry | ✓ NPPES | Weekly updates |
| Medicare Enrollment | ✓ PECOS | Monthly updates |
| Practice Data | ✓ Medicare Util. | Annual (CY lag) |
| Industry Payments | ✓ Open Payments | CY 2024 |
| Disciplinary History | — Not public | N/A |
This provider has data in 4 of 4 available federal datasets, with a Data Coverage level of Very High. This reflects how much public data is available about a provider. How we calculate this →
Summary
Dr. Chang is a mixed practice specialist, with above-average Medicare volume (top 6% in CA), with low-engagement industry engagement.
This summary is auto-generated from federal data, describing data availability and patterns. Read our methodology →
Frequently Asked Questions
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All data on this page is sourced verbatim from public federal records published by the U.S. Centers for Medicare & Medicaid Services (CMS): NPPES ↗, Open Payments ↗, Medicare Provider Utilization ↗, and PECOS. Publication is mandated by the Physician Payments Sunshine Act (§6002 ACA, 42 U.S.C. §1320a-7h) and the Freedom of Information Act.
This page is not medical advice, an endorsement, a recommendation, or a quality rating. Data Coverage reflects data completeness — how much federal information exists for this provider — not clinical performance, patient outcomes, or quality of care. Always verify information directly with the provider and consult a licensed clinician before making medical decisions.
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