About one-third of adults in the U.S., or 33 percent, went without recommended health care due to expensive costs, according to a Commonwealth Fund survey.

The survey was conducted in 11 countries including the United States, Australia, Canada, France, Germany, the Netherlands, New Zealand, Norway, Sweden, Switzerland, and the United Kingdom. From March to June 2016, the group asked 26,863 adults who were 18 years and older about various aspects of their health care coverage.

The survey found adults in the United States were far more likely than adults in other countries to go without recommended care such as foregoing doctor visits when sick and failing to fill prescriptions because of costs. In the U.K. and Germany, 7 percent of adults faced cost problems.

Low-income adults found it difficult to afford care. Forty-three percent of low-income adults in the United States said they went without care due to affordability, which was the highest rate of any country surveyed.

"Relative to other countries, the health care system in the United States appears to perform poorly in meeting several population health goals," the report states. "Out-of-pocket spending is an important barrier to care in the United States, reducing access to services."

For those who are chronically ill in the United States, 14 percent believed they did not have the support they needed from their health care provider to manage their situation.

The survey also found that adults in the United States found it difficult to see a doctor quickly. More than one-third of low-income adults, or 35 percent, waited six days or more to see a doctor and 17 percent of higher-income adults said the same. More than half of U.S. adults, or 51 percent, said they struggled to find care in the evenings and weekends without going to the emergency room.

"The availability of after-hours care, coordination of care, and management of chronic illness are especially problematic, as seen in this survey and our previous survey of older adults," the study says. "Compared to other surveyed countries, the United States is notable for having a larger share of the population that reports multiple chronic conditions and material hardship."

According to the study's authors, improvements to the current U.S. system need to be made to help the sickest and poorest Americans.

"Previous surveys have shown that, especially compared to other industrialized nations, the U.S. has far too many people who can't afford the care they need, even when they have health insurance," said Robin Osborn, the study's lead author. "This survey underscores that we can do better for our sickest and poorest patients, and that should be a high priority in efforts to improve our current system."

The Department of Health and Human Services did not immediately respond to requests for comment by press time.