While the prevalence of pre-existing conditions varies between states, outhern states tended to have more people with pre-existing conditions. (Photo: Shutterstock)

More than one in four Americans—54 million people—could lose health insurance due to pre-existing conditions, without the protections of the Affordable Care Act (ACA). That analysis comes from a new study from the Kaiser Family Foundation (KFF).

The report is an update of a 2016 analysis which found that 27 percent of American adults under 65, at that time equaling 52 million people, would not qualify for insurance under pre-existing condition exclusions prior to the ACA. The percentage today remains 27 percent, based on data about pre-existing conditions drawn from the National Health Interview Survey.

Related: How do those with ACA insurance feel about its future?

The KFF researchers say nearly half of American families—45 percent—have at least one nonelderly adult member with a pre-existing health condition that would have affected their insurance coverage before passage of the ACA.

Threat from Texas vs. Azar case

The new analysis was conducted as the Fifth Circuit Court of Appeals weighs a decision in the Texas v. Azar case, which was brought by 20 Republican state officials and joined by the Trump Administration. That suit which seeks to overturn the ACA in its entirety, including provisions that prohibit insurers from denying coverage or charging more to people with pre-existing conditions.

The case is likely to go to the Supreme Court, which has rebuffed earlier efforts to dismantle the ACA. However, with a more conservative Court now in place due to the appointments by President Trump, the outcome of the case is difficult to predict.

The study notes that since the ACA went fully into effect in 2014, Americans with pre-existing health conditions have been protected from being excluded from health coverage or paying higher premiums because of pre-existing conditions.

"Before the ACA protections took effect in 2014, private insurers in the individual market could use applicants' health status, history and other risk factors to determine whether and under what terms to issue coverage," the report noted. "Some conditions that could lead to automatic denials of coverage at the time include cancer, diabetes, epilepsy, heart disease, and pregnancy."

Red states will be hit harder

One interesting finding of the KFF analysis is that southern states, which historically have tended to have vote Republican, are likely to have more people affected. The researchers found that the rates for pre-existing conditions that would have affected insurance coverage pre-ACA vary from state to state. However, southern states tended to have more people with pre-existing conditions.

"On the low end, in Colorado, at least 22 percent of non-elderly adults have conditions that would likely be declinable if they were to seek coverage in the individual market under pre-ACA underwriting practices," the study said. "Rates are higher in other states – particularly in the South – such as Arkansas (34 percent), Kentucky (34 percent), Mississippi (34 percent), and West Virginia (37 percent), where at least a third of the non-elderly population would have declinable conditions."

The KFF report warns that regardless of state, the impact of overturning the ACA would be felt widely throughout the country. "The [ACA] assures people access to individual market coverage with comprehensive benefits through a variety of changes in their work and life circumstances. This could change quite quickly if the ACA market protections for people with pre-existing conditions were invalidated," the report says. "Over a quarter of nonelderly adults have a health condition that would jeopardize their access to non-group coverage without the ACA market protections, potentially affecting almost one-half of non-elderly families in the country."

Read more: 

• Fact check: Pre-existing condition protections and the ACA
• What would health care be like in a post-ACA world?
• Will Obamacare survive? Experts weigh in.