Changes in Opioid Overdose Emergency Encounters Associated with Expansion of Wisconsin Medicaid to Childless Adults in Poverty.

OBJECTIVE

The purpose of this study was to measure changes in the payer mix and incidence of emergency department (ED) opioid-related overdose encounters after an April 2014 expansion of Medicaid to childless adults led to a 43% increase in Medicaid coverage for men and 8% for women statewide.

METHOD

We explored two competing hypotheses using data visualization and comparative interrupted time-series analysis (CITS): (a) expanded eligibility for Medicaid is associated with a change in payer mix only and (b) sociodemographic groups that gained Medicaid eligibility were more likely to use ED services for opioid overdose. Data included encounters at all Wisconsin nonfederal hospitals over 23 quarters from 2010 to 2015 and American Community Survey estimates of pre- and post-policy Medicaid eligibility by sex and age.

RESULTS

We found an increase in the share of opioid-related ED visits covered by Medicaid for men and women ages 19-29 and for men ages 30-49 following the expansion. The number of visits increased substantially in April 2014 for men ages 30-49, with Medicaid-covered visits driving this result. We found little evidence of an increase in overall visits for other age groups for either men or women.

CONCLUSIONS

The relationship between Medicaid expansion and opioid ED use is complex. Changes in case mix and increased access to care likely both play a role in the overall increase in these ED visits. Being uninsured may be an important barrier to seeking emergency care for opioid-related overdoses.