At least one in four U.S. adults could be uninsurable due to a pre-existing condition in the wake of a repeal of the Affordable Care Act, according to an estimate by the nonprofit Kaiser Family Foundation.

Those adults, or about 52 million people, have a current or past diagnosis that could allow health insurers to refuse them health coverage, the Kaiser analysis found.

Most adults get health insurance through their employer or public programs and are thus shielded from this aspect of the health insurance industry. But others, including self-employed people, lower-wage workers, early retirees and those in need of coverage in-between life changes, seek coverage on the individual insurance market.

The “vast majority” of that 52 million population is covered through their employer or public programs, according to the Dec. 12 Kaiser report. But if any of those people lost insurance because of unemployment, divorce, turning 26 or another reason, their pre-existing condition would become an even bigger problem.

The scope of what has been considered a pre-existing condition can be shocking.

Before the ACA, excludable pre-existing conditions included people who had diabetes, obesity or mental disorders (including being bipolar or having an eating disorder) or had been treated for alcohol or drug abuse, the Kaiser report shows.

The label also applied to those who’d had an organ transplant, a stroke, cancer, hepatitis C, were awaiting surgery or hospitalization, or even suffered from sleep apnea.

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The Kaiser analysis focused on medical conditions. But there were other ways people could be declined for coverage in a pre-ACA world, including for being on certain medications and being employed in certain high-risk occupations.

For example, Blue Cross Blue Shield of Illinois declined coverage for those on a number of anti-arthritic, anti-cancer, anti-coagulant/anti-thrombotic, anti-diabetic and anti-psychotic medications, according to the Kaiser report. The list included AbbVie’s ABBV, -1.64% Humira, GlaxiSmithKline’s GSK, -0.55% Avandia and Bristol-Myers Squibb’s BMY, +0.39% Abilify, among other popular medications.

President-elect Donald Trump has said he’d consider keeping some provisions of the ACA, including coverage for those with pre-existing conditions.

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But experts say it may be easier said than done: The ACA’s most criticized provision — the individual mandate to buy health insurance — helped make it possible for pre-existing conditions to be covered.

Why? It comes down to healthy young people, who are critical to stabilizing the insurance pool’s costs but might not buy health insurance at all without some kind of incentive.

Without the individual mandate, “people who are most at risk of high health-care costs would be the most likely to enroll,” the American Academy of Actuaries wrote in a recent letter to House Speaker Paul Ryan and Minority Leader Nancy Pelosi. “Premiums for the remaining pool would increase as a result. ... A premium spiral could result, with fewer and fewer insureds and higher and higher premiums.”

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Republican leadership hasn’t coalesced around a single ACA replacement.

One Republican proposal, delineated in Ryan’s “A Better Way” plan, would replace the individual mandate with incentives for maintaining continuous health insurance. That would make it more expensive for those who haven’t maintained continuous coverage to get insured again, though the white paper does not specify the magnitude of that expense.



There’s evidence that the Trump White House would support the idea, with Trump’s health-care plan including its own mention of continuous coverage.

Read more: Here’s what we know so far about President-elect Trump’s post-Obamacare health plan

This article was first published on December 12, 2016.