From the mailbag: Can someone please explain this to me? My father has (Big Name Insurance Company) Medicare. I was just informed by the therapist where he is receiving physical therapy after an accident that Big Name Insurance Company Medicare will not cover his stay past the end of this week, even though he is not ready to come home. The therapist said if he had regular Medicare he would still be covered.

Your father probably has a Medicare Advantage plan administered by Big Name Insurance Company. These are Medicare plans managed by private insurance companies, rather than Medicare. For a fixed premium, these Medicare Advantage plans are supposed to provide health coverage equivalent to what's provided under traditional Medicare.

The attraction of Advantage plans to seniors is that they almost always combine various kinds of insurance into one plan: the hospital and outpatient coverage of traditional Medicare, supplementary coverage for out of pocket expenses not covered by traditional Medicare, as well as medications. Seniors are drawn to these plans because the total premium to them is often lower than all these costs would be if purchased separately, and on the surface the plans are far less confusing.

For many seniors the primary disadvantage to these plans, which they often do not experience until they need a certain level of care, is the managed-care aspect of Advantage plans. While traditional Medicare leaves it to the medical professionals to make decisions about kind, duration and location of treatment, Advantage companies control many of these decisions. Patients must use the services of medical professionals and facilities who participate in the specific Advantage program. Case managers at the insurance company make many decisions about the care provided and what will be covered. In essence, most Medicare Advantage plans are HMOs.

While traditional Medicare will cover the cost of impatient rehabilitation for up to 100 days - assuming the patient continues to progress toward a measurable goal, and with some aggressive co-payments if there is no supplementary insurance  - very few Medicare Advantage providers will routinely agree to pay for this amount of care. For this reason most rehab doctors and therapists prefer to work with traditional Medicare.

It is possible to switch from a Medicare Advantage program back to traditional Medicare. However, be aware that if he does your father will either have to find supplementary insurance to cover deductibles and co-payments, or face considerable potential out of pocket expense in the future. He may find himself spending more each month for his health insurance, but reaping better coverage down the road.

In the meantime he will lose nothing by immediately appealing the discharge decision made by the case manager at (Big Name Insurance Company) Medicare. He should have received a notice about his pending discharge with information about how to appeal to the company on the form.