More than three-quarters of adult Americans who have health insurance say they still worry about paying more for their medical care, and nearly 50 percent say they’re “very” or “extremely” worried about the issue, a new Harris Interactive/HealthDay poll shows.

More than half (57 percent) of those polled said they feared losing their health insurance sometime in the future, which may explain another key finding in the poll — sizeable numbers of Americans said they’re skipping doctor visits or not getting prescriptions filled to save money.

Middle-aged Americans — people too old to be blasé about their health but too young to be covered by Medicare — seemed most worried about paying their health care bills. Among insured individuals aged 45 to 64, a full 84 percent said they were concerned that rising health care costs would exceed their ability to pay.

Only 8 percent of all insured Americans polled were “not at all worried” about getting health care coverage.

“Many are, in fact, not filling prescriptions, skipping a doctor’s visit, not following up on something that was recommended by the doctor, taking a medication less or pill-splitting, doing without dental care,” said Humphrey Taylor, chairman of The Harris Poll.

He added that with the economy in a tailspin and many Americans losing their employer-based health insurance, the problem may only get worse. “If the number of uninsured rises sharply, one would expect to see these numbers increase,” Taylor said.

One consumer advocate wasn’t surprised by the results of the poll, which included 2,078 adults surveyed between Feb. 25 and 27.

“Even for people who have insurance, increasingly, the costs have been shifted to them — and those costs have risen,” said Carol Pryor, policy director at The Access Project, a nonprofit group dedicated to making health care available to more Americans. More and more, she added, insured Americans are paying higher deductibles and co-pays, stretching their ability to get proper medical care.

Pryor agreed with Taylor that the situation is only likely to get worse, since “more people are becoming uninsured as a result of the economic meltdown.”

Some other key findings from the poll:

• 78 percent of adults with health insurance worry about paying more for their medical care.
• Nearly two-thirds (65 percent) of all insured adults say they’re worried about how they can afford to pay for medical care and prescription drugs, with that number rising to 76 percent among people aged 45 to 54. Even among those aged 65 and over — most of whom are eligible for Medicare — 62 percent say they worry about paying for the care they need.
• Over the past year, one in five insured adults skipped filling a prescription because of the cost. That number jumped to 30 percent for those without insurance.
• Similarly, cost concerns led 24 percent of the insured and 51 percent of the uninsured to forgo seeing a doctor for a specific medical problem. Twenty-one percent of the insured and 33 percent of the uninsured didn’t get a recommended follow-up test or treatment for the same reason.
• Trying to cut down on medical expenses, 14 percent of the insured and 19 percent of the uninsured took a medication at a lower dose than that recommended by a doctor.
• Dental care took the biggest hit: 51 percent of the uninsured and 30 percent of the insured skipped necessary dental care over the past year due to financial concerns.

Forgoing care to save costs over the short term may not save costs over the long term, the experts warned. “Some things do go away on their own over time,” Pryor said. “But there are a lot of conditions that get worse if they aren’t treated, and they then require more expensive care later. So it’s definitely a gamble.”

Taylor noted that the statistics on the percentage of Americans skipping needed care have remained about the same since 2007, when Harris first asked these types of questions. That may seem odd given the recent downturn in the economy, he added. But, he noted that even if a few million Americans lose their health insurance, that’s still only 2 percent of the adult population — not enough to show up in this type of survey.

The new poll results come on the heels of a report released Wednesday by the nonprofit advocacy group Families USA. It found that a third of Americans under the age of 65 — nearly 87 million people — went without health care coverage at some point over the past two years.

The most recent U.S. government statistics suggest that 16 percent of all adults (including those 65 and older) have no health insurance. And a Commonwealth Fund report published last June found that the number of “underinsured” — people who have insurance that doesn’t fully meet their health care needs — rose by 60 percent between 2003 and 2007.

The issue gained momentum in the nation’s capitol last Thursday, when President Barack Obama convened a long-anticipated White House summit on health care reform. The Associated Press reported that Obama made a point of bringing a wide range of views to the table — voices representing the insurance industry, patient groups, physicians and even those advocating a single-payer system.

“Every voice has to be heard. Every idea must be considered,” Obama said during the summit. “The status quo is the one option that is not on the table.”

According to Pryor, one item that should be up for discussion in Washington is the plight of the underinsured.

“Covering the uninsured is only part of the problem,” she said. “Unless reform includes adequate, comprehensive and affordable coverage, just having insurance will not be protection — either from facing barriers to care or concern over one’s financial stability. And after all, those two things are the function of insurance.”