The Impact of Medicaid on Medical Utilization in a Vulnerable Population: Evidence from COFA Migrants

In March 2015, the State of Hawaii stopped covering the vast majority of migrants from countries belonging to the Compact of Free Association (COFA) in the state Medicaid program. COFA migrants were instead required to obtain private insurance in the exchanges established under the Affordable Care Act. Using statewide administrative hospital discharge data, we show that Medicaid-funded hospitalizations and emergency room visits declined in this population by 69% and 42% after the expiration of Medicaid eligibility. This decrease occurred despite the fact that low-income COFA households were eligible for state-funded premium coverage for private insurance. Utilization funded by private insurance did increase, but not enough to offset the declines in Medicaid-funded utilization. Uninsured ER visits increased as a consequence of the expiration of Medicaid benefits. Paradoxically, we also find a substantial increase in Medicaid-funded ER visits by infants after the expiration of benefits.