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Medical Care

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Health insurance, Medicaid, Cost of medical care, United States. Patient Protection and Affordable Care Act, Medicaid -- Oregon


Background—There is interest in assessing healthcare utilization and expenditures among new Medicaid enrollees after the 2014 Medicaid expansion. Recent studies have not differentiated between newly enrolled individuals and those returning after coverage gaps.

Objectives—To assess healthcare expenditures among Medicaid enrollees in the 24 months after Oregon’s 2014 Medicaid expansions and examine whether expenditure patterns were different among the newly, returning, and continuously insured.

Research Design—Retrospective cohort study using inverse-propensity weights to adjust for differences between groups.

Subjects—Oregon adult Medicaid beneficiaries insured continuously from 2014-2015 who were either newly, returning, or continuously insured.

Measures—Monthly expenditures for inpatient care, prescription drugs, total outpatient care, and subdivisions of outpatient care: emergency department (ED), dental, mental and behavioral health (MBH), primary care (PC), and specialist care.

Results—After initial increases, newly and returning insured outpatient expenditures dropped below continuously insured. Expenditures for ED and dental services among the returning insured remained higher than among the newly insured. Newly insured MBH, PC, and specialist expenditures plateaued higher than returning insured. Prescription drug expenditures increased over time for all groups, with continuously insured highest and returning insured lowest. All groups had similar inpatient expenditures over 24 months post-Medicaid expansion.

Conclusions—Our findings reveal that outpatient expenditures for new non-pregnant, non-dual-eligible Oregon Medicaid recipients stabilized over time after meeting pent-up demand, and prior insurance history affected the mix of services that individuals received. Policy evaluations should consider expenditures over at least 24 months and should account for enrollees’ prior insurance histories.


This is the authors' version of a paper that subsequently appeared in final edited form in Medical Care, vol. 56, no. 5, May 2018. Published by Wolters Kluwer. May be accessed at



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