Time trends in emergency department use among adults with intellectual and developmental disabilities.

Background: Emergency Department (ED) visits are common among adults with intellectual and developmental disabilities (IDD). However, little is known about how ED use has varied over time in this population, or how it has been affected by recent Medicaid policy changes.

Objective: To examine temporal trends in ED use among adult Medicaid members with IDD in eight states that ranged in the extent to which they had implemented state-level Medicaid policy changes that might affect ED use.

Methods: We conducted repeated cross-sectional analyses of 2010-2016 Medicaid claims data. Quarterly analyses included adults ages 18-64 years with IDD (identified by diagnosis codes) who were continuously enrolled in Medicaid for the past 12 months. We assessed change in number of ED visits per 1000 member months from 2010 to 2016 overall and interacted with state level policy changes such as Medicaid expansion.

Results: States with no Medicaid expansion experienced an increase in ED visits (linear trend coefficient: 1.13, p < 0.01), while states operating expansion via waiver had a much smaller (non-significant) increase, and states with ACA-governed expansion had a decrease in ED visits (linear trend coefficient: 1.17, p < 0.01). Other policy changes had limited or no association with ED visits.

Conclusions: Medicaid expansion was associated with modest reduction or limited increase in ED visits compared to no expansion. We found no consistent decrease in ED visits in association with other Medicaid policy changes.