A KHN review of hospital finances in the country's 306 hospital markets found that several of the most profitable markets also have some of the highest levels of patient debt. Overall, about a third of the 100 million adults in the U.S. with health care debt owe money for a hospitalization, according to a poll conducted by KFF for this project. Close to half of those owe at least $5,000. About a quarter owe $10,000 or more.