Medicare requires a 20 percent co-payment by patients on chemotherapy medicines, but before 2005 doctors sometimes forgave those co-payments because their profits were so great.

Beneficiaries would not pay the 20 percent co-payment or the 25 percent premium extracted for other Part B services.

New co-payments are also likely, particularly a 20 percent co-payment for users of home health care services.

"A 20 percent co-payment for home care would be a regressive sick tax on the most vulnerable and disabled Americans," she said.

But last year the policy switched to a 30 percent co-payment for self-injected drugs, and she began paying nearly $400 a month.

As a result, an apparent 20 percent co-payment may represent 30, 40, 50 percent or more of total charges.

Because management for medical necessity allows for lower co-payments, people are able to get treatment who could never afford the traditional indemnity plan's 50 percent co-payment.

Since by that year her insurance required a 20 percent co-payment, she was asked to pay the remaining $440 of the bill.

For families facing major illness, insurance policy limits or even the requirement of a 20 percent co-payment can prove financially ruinous.

The hospital fees, not including the doctor bills, totaled $5,709, which meant that his 20 percent co-payment was $1,141.80.