According to one insurance company, the term "variable copay" has to do more with where services are rendered rather than by whom. Many doctors are able to practice at more than one hospital or more than one type of facility. The contracts each particular doctor has with each insurance company and with each facility affects the copay. Therefore the term "variable."
Let me give an example to illustrate. Dr. Jones can practice at both Baptist and at Centennial Hospitals. If, let's say, your scheduled procedure was performed at Baptist, your copay is $100. Whereas the same procedure costs $500 at Centennial because of the agreements and "contractual amounts" agreed upon between the facility and the insurance company. To avoid unexpected costs with variable co-pays:
1. Find out where your doctor can practice.
2. Call your insurance company and see if there are any variations in payments and in the amounts you will have to pay.
3. If the fee schedules are the same at all of your doctor's locations, ask if when this might change in the future, if at all.
4. Also ask what type of facilities these variable rates, if any, apply. For example, would your rates ever vary for procedures performed in your doctor's office. "Variable co-pays" seem to only pertain to hospitals, outpatient centers, specialized facilities such as rehab centers, and surgery centers, but it never hurts to be sure you have all of the information.
Personally, I would avoid these types of plans because it seems to me that it gives a provider/insurance company a possible loophole. While you could appeal an insurance company's partial payment or outright denial of payment and can prove what the actual schedule fees were at the time services were rendered, I wouldn't want to go through that hassle especially at a time when I need insurance the most.
The difference in savings between a variable copay and non-variable copay policies would have to be very substantial and the insurance company would have to be reputable at servicing its claims.