As one might expect, the percentage of delayed care was highest among the lowest paid—among households earning less than $40,000 annually.

The highest percentage of Americans since Gallup started asking the question are letting serious medical conditions go without care, because they can't afford it.

That's according to a new Gallup report, which finds that 25 percent of respondents say they've foregone medical care because of the cost for a serious condition—up from 19 percent a year ago and reflecting a near-50 percent increase in that number since Gallup began asking about it in 2001. And that can have serious repercussions for the economy.

Says the report, "Such delays in medical treatment, whether for injuries, illnesses or chronic conditions, can have significant implications for the economy and health care system, but also the political climate." Some of those implications include reduced productivity and increased health care costs—a double-whammy that will have a notable impact on the economy.