Roughly 240,000 more Missouri Medicaid recipients on Monday will be switched to a system under which private companies oversee patient care.
The expansion will mean the managed-care program currently in 54 counties along I-70 will expand throughout the state. Those who had been enrolled with Aetna will be switched to UnitedHealthcare, WellCare or Home State Health Plan, a division of Centene.
Missouri seniors, the blind and people with disabilities on Medicaid will not be impacted.
About 500,000 people had been getting health care through managed care, with the rest on a fee-for-service plan. The state pays private companies to manage patients' health care under managed care. Under the fee-for-service model, physicians are reimbursed as patients are treated.
Missouri lawmakers in 2015 passed a budget that called to expand managed care throughout the state that some supporters argued would save money by incentivizing private companies to keep health care costs down.
But the switch has met pushback from legislators who say the change was shoved through too quickly and without enough public input.
Republican Sen. Rob Schaaf, a St. Joseph family physician and one of the most vocal opponents of managed care, tried and failed to get funding for the switch taken out of next fiscal year's proposed budget.
He's raised questions about the May rollout while state funding is on hold until the next budget takes effect in July, lack of input when the expansion was added to the fiscal year 2016 budget and tight deadlines for network adequacy testing and federal waivers.
"It's illegal, it's unconstitutional, it's not going to better care (and) there's a serious question as to whether it will save the state any money," Schaaf told colleagues on the Senate floor during debate on the budget.
Schaaf said the process for expansion has been expedited in order to push the policy change through, although Department of Social Services Acting Director Jennifer Tidball has told lawmakers the pace is not unusual.
Senate Appropriations Committee Chairman Dan Brown said residents already using managed care in his Rolla-area district haven't raised issues.
"I'm just not hearing complaints," Brown said Wednesday. "It would seem as though they're pretty happy about the services."