137 million Americans suffered hardships from medical costs: American Cancer Society The American Cancer Society estimates more than 137 million are affected.

More than 137 million U.S. adults, about 56%, have suffered because of costs tied to medical care, according to a study released Thursday by the American Cancer Society.

Adults aged 18 to 64 suffered more than seniors, according to National Health Interview Survey data collected from 2015 to 2017. Compared with Americans 65 or older, younger adults reported higher rates of material (28.9% to 15.3%), psychological (46.9% vs. 28.4%) and behavioral (21.2% vs. 12.7%) medical financial hardship.

The study, which appears in the Journal of General Internal Medicine, evaluated concerns including the affordability of care, potentially delaying care until it could be paid for and related stress factors.

High out-of-pocket costs are becoming an "increasingly critical issue for patients," the ACS said on its website. "It can lead to a depletion of assets and medical debt, as well as distress and worry about household finances."

Adults aged 18 to 64 with less educational attainment suffered even more, according to the study. Women suffered more than men. Uninsured Americans were the most likely to report multiple instances of hardship.

Until significant action is taken, the study's authors said, conditions are likely to worsen.

"With increasing prevalence of multiple chronic conditions; higher patient cost-sharing; and higher costs of healthcare; the risk of hardship will likely increase in the future," the authors wrote. "Thus, development and evaluation of the comparative effectiveness and cost-effectiveness of strategies to minimize medical financial hardship will be important."