Medical problems are still the most common cause of personal bankruptcy in the U.S., according to a new study in the American Journal of Public Health.

Using a sample of 910 Americans who filed for personal bankruptcy between 2013 and 2016, researchers from the Consumer Bankruptcy Project found that medical issues contributed to 67.5 percent of all personal bankruptcies during that time. Earlier CBP research found that medical issues contributed to 65.5 percent of personal bankruptcy filings between 2001 and 2007, before the passage of the ACA.

"Despite gains in coverage and access to care from the ACA, our findings suggest that it did not change the proportion of bankruptcies with medical causes," the authors wrote. They estimated that about 530,000 families file for bankruptcy each year due to illness or medical bills.

Dr. David Himmelstein, the lead author of the study, said that inadequate health insurance plays a major role in personal bankruptcy: "Unless you're Bill Gates, you're just one serious illness away from bankruptcy. For middle-class Americans, health insurance offers little protection. Most of us have policies with so many loopholes, copayments and deductibles that illness can put you in the poorhouse. And even the best job-based health insurance often vanishes when prolonged illness causes job loss—just when families need it most. Private health insurance is a defective product, akin to an umbrella that melts in the rain."