Health reform has helped to slowly shrink the population of young Americans who are uninsured, according to a recent study. Still, millions have little to no coverage, ahead of the rollout of insurance exchanges in 2014, sometimes resulting in disastrous financial consequences.

Using random phone surveys of adults, ages 19 to 64, during a four-month period last year, The Commonwealth Fund found a sizeable bump in the number of young adults with health insurance. About 48 percent of those surveyed ages 19 to 25 had coverage last year, researchers found, an uptick from 41 percent a few years prior. The increase was likely due to the provision in the Affordable Care Act that allows parents to keep kids on their insurance plan until they're 26, according to the study.

Yet still, about 84 million Americans, or half of working-age adults, remained without insurance, or had out-of-pocket costs so high that they could be classified as underinsured.

"Overall, the survey shows the continuation of the bad news that sparked the move to reform our dysfunctional health care system," David Blumenthal, M.D., president of The Commonwealth Fund, said during a conference call with reporters yesterday. "To begin with, large numbers of uninsured Americans, millions facing problems getting health care they need, they're financially squeezed by burdensome medical bills, and far too many Americans are hampered by medical debt."

About 80 million people reported last year that they skipped going to the doctor or didn't fill a prescription because of the cost, the study found. That's an increase from the 63 million who reported doing the same in 2003.

A large number of those who did make it to the doctor's office struggled to foot the bill. About 41 percent of working-age adults, or 75 million, said they were having difficulty paying off their medical debts, or were dedicating a portion of their earnings to health-related IOUs. Some 18 percent were contacted by collections agencies regarding unpaid medical debts last year, and 16 percent said they had to change their way of life because of that burden. An estimated 4 million people had to declare bankruptcy because of their medical bills, the survey found.

It's still too early to say how much of an impact insurance exchanges will have on the ranks of the uninsured, Blumenthal said, but he believes the data signals the importance of continued implementation of the Affordable Care Act.

"The cost of health care and health coverage in the United States has been on an unsustainable upward trajectory over several decades, straining family and government budgets," he said. "It's important that lawmakers and regulators across the country take the steps required to ensure that all Americans can benefit fully from the law's improvements to the quality, efficiency and affordability of our health care system."

Here are a couple of more highlights from the report:

  • Some 87 percent of those who were uninsured during some part of 2012 would be eligible for subsidized health insurance sold through exchanges, or expanded Medicaid, though that number could change depending on the percentage who aren't legal citizens.
  • As many as 85 percent of the 30 million underinsured in 2012 could be eligible for expanded Medicaid or subsidized health insurance.
  • The uninsured were less likely to receive preventative care, the study found. For example, about 48 percent of women without insurance in 2012 received a mammogram during the recommended period, compared to 77 percent of insured women.
  • Income was a huge factor in whether Americans had adequate insurance, or any coverage at all. About 75 percent of working-age adults with low incomes (less than $14,856 for an individual) were uninsured or underinsured last year.