Despite expectations that Medicare accountable care organizations (ACOs) would curb health care spending, their effect has been modest. One possible explanation is that ACOs' inability to prohibit out-of-network care limits their control over spending. To examine this possibility, we examined the association between out-of-network care and per beneficiary spending using national Medicare data for 2012-15. While there was no association between out-of-network specialty care and ACO spending, each percentage-point increase in receipt of out-of-network primary care was associated with an increase of $10.79 in quarterly total ACO spending per beneficiary. When we broke down total spending by place of service, we found that out-of-network primary care was associated with higher spending in outpatient, skilled nursing facility, and emergency department settings, but not inpatient settings. Our findings suggest an opportunity for the Medicare program to realize substantial savings, if policy makers developed explicit incentives for beneficiaries to seek more of their primary care within network.
Keywords: Accountable care organizations; Beneficiaries; Costs and spending; Health policy; Health reform; Medicare; Medicare savings programs; Primary care; Primary care providers; Specialty care; Traditional Medicare.