The Affordable Care Act requires everyone to have health insurance or pay a fine, and prohibits insurance companies from discriminating against customers because of pre-existing conditions.
These two provisions are supposed to balance each other out — bringing younger, healthier people into the insurance market to counteract the influence of the sick.
But the Society of Actuaries cautioned that high-cost patients could still overwhelm the system, driving up claims costs — and later, premiums.
Study authors noted that claims increases will vary dramatically by state on the individual insurance market, rising 62 percent in California and more than 20 percent in Florida by 2017.
The report did not release estimates for the employer-based health insurance market, where most families by their coverage.
The Obama administration said the study is incomplete and ignores several factors, including premium tax credits and market competition at the state level, that will ease costs for working families.