The number of people who have health insurance and still pay a lot for medical bills has jumped by 60 percent since 2003, a report out today showed. And it is contributing to many bankruptcies, an Augusta attorney said.

The number of underinsured -- people with coverage who still devote a significant portion of their income to health care -- increased from 16 million in 2003 to 25 million last year, the Commonwealth Fund reported. Add that to the uninsured, and it means that 75 million Americans, or 42 percent of all adults younger than 65, lack adequate coverage, said Cathy Schoen, the lead author and senior vice president for research and evaluation at Commonwealth.

The biggest increase in the underinsured came from those whose income is double the federal poverty guidelines, or more than $40,000 a year for a family of four.

"Disturbingly, the percent underinsured in this middle- to higher-income group nearly tripled over the four years," Ms. Schoen said.

Many in this category are paying more for premiums but getting fewer benefits or facing limitations on how much insurance will pay. Fifty-three percent skipped care or didn't fill prescriptions because of cost concerns.

High deductibles were also a culprit -- 26 percent of the underinsured had deductibles of $1,000 or more, said Sara Collins, the co-author of the study published today in the online version of Health Affairs .

"And surprisingly, underinsured adults are also more likely to have high premiums and to spend a large share of their income on premiums," she said.

Nor surprisingly, 45 percent of the underinsured said they had trouble paying medical bills, with some turning to loans or mortgages or piling up debt on their credit cards, Ms. Schoen said.

Augusta bankruptcy attorney Terry Leiden sees it often -- he estimates that about 30 percent of his clients are people who would qualify as underinsured. A major illness knocks them out of work and they start putting those bills on the credit cards or borrow more money, worsening the problem.

"A lot of people don't realize it, but many insurance policies have a lifetime pay and an annual pay (limit)," Mr. Leiden said, and the patient is on the hook after that. One of his clients had a premature infant and ran up $450,000 in medical bills in five months.

"That's the lifetime benefit" limit, he said. "So when that child was 5 months old, the medical insurance on that child ended."