The idea that Medicaid expansion will wreak havoc on state budgets due to increased hospital use by the previously-uninsured was challenged by results of a recent study by the UCLA Center for Health Policy Research. While rates of hospital and emergency room use rose soon after people enrolled in low-cost, government health plans, utilization of these services dropped off within a year, researchers found. 
The study examined data on 182,000 Californians insured through county-run programs for low-income people between 2011 and 2013.
Researchers found that subjects who previously had the least medical care used hospital emergency rooms at a rate of 600 visits per 1,000 enrollees in the first three months of coverage. But utilization fell sharply in subsequent quarters, plateauing at a rate of 183 visits per 1,000 enrollees by the end of the second year. The overall utilization decline for emergency visits in the study's time period was 69.5 percent, the researchers found, and subjects' hospital admissions fell by 78.5 percent.
"California's success should set an example for states that are on the fence about expanding Medicaid," study co-author and UCLA professor Gerald F. Kominski, Ph.D., said in the announcement. "It's an investment: Build more infrastructure and care delivery early on, and you can manage chronic care, address unmet healthcare needs and keep cost increases to a manageable level."
But it's hard to know if coverage expansion will permanently lower emergency room use, the Los Angeles Times reported. ER visits have been rising nationwide for the last 20 years and not just because the uninsured have no other treatment options, Renee Y. Hsia, M.D., associate professor of emergency medicine at UC San Francisco, told the LA Times. And the UCLA study didn't find a contemporaneous rise in outpatient care that might be expected if patients were visiting doctors instead of emergency rooms.
Hsia published a different study recently in the Journal of the American Medical Association that showed children's ER visits in California increased for all insured populations between 2005 and 2010. And the privately-insured group showed one of the fastest growth rates.
"It kind of refutes the idea that the ACA is going to solve all our problems," Hsia told the LA Times.
For more:
- here's the study (.pdf)
- read the LA Times article
- see the UCLA study announcement
- check out the JAMA study