Critics of the cuts worry the trend will accelerate, leaving poor and sick patients with no way to get to medical appointments.
"I wouldn't be surprised to see more of these waivers in the pipeline," said Joan Alker, executive director of the Georgetown University Center for Children and Families.
Because medical transportation isn't typically covered by the commercial insurance plans most Americans use, it's unfamiliar to many people and could be seen as unnecessary, said Eliot Fishman, senior director of health policy for Families USA, a nonprofit, nonpartisan consumer health advocacy group.
Formerly a Medicaid official in the federal government, Fishman called the transportation program "vital" not only for children with severe disabilities, but also for non-elderly, low-income adults.
CMS released results of a 2014 survey of Medicaid users, which found that lack of transportation was the third-greatest barrier to care for adults with disabilities, with 12.2 percent of those patients reporting they couldn't get a ride to a doctor's office.
"This is not something to be trifled with lightly," Fishman said. "We're talking about a lifesaving aspect of the Medicaid program."
About 3.6 million Americans miss or delay non-emergency medical care each year because of transportation problems, according to a 2005 study published by the National Academy of Sciences.
That same study analyzed costs for providing NEMT to patients facing 12 common medical conditions and found that providing additional transportation is cost-effective. For four of those conditions -- prenatal care, asthma, heart disease and diabetes -- medical transportation saved money when the total costs for both transportation and health care were tallied.
Medicaid is required to provide NEMT services using the most appropriate and least costly form of transportation, whether that's taxis, vans or public transit.
Most states rely on NEMT brokers or managed-care organizations to administer the transportation services. Other states run the service directly, paying providers on a per-ride basis, while some use local ride services and pay independent taxi firms to shuttle patients.