Impact of a statewide Emergency Department Information Exchange on health care use and expenditures

Objective: To assess the effects of a program mandating the statewide adoption of an Emergency Department Information Exchange (EDIE) on health care utilization and spending among Medicaid enrollees in Washington state. Data Source: Medicaid claims and managed care encounters from the Washington Health Care Authority. Study Design: A difference-in-differences analysis with trends was used to compare changes in ED visits, inpatient admissions, primary care visits, and expenditures among frequent ED users (≥5 ED visits in past year) to those of infrequent users through the second year Washington's program. Data Extraction: The study population included adult Medicaid enrollees with ED visits between January 2010 and October 2014. Principal Findings: There were 505,667 ED visits among 153,543 unique enrollees included in the analysis. Washington's program was associated with a small, but statistically significant differential change of −0.70 ED visits per enrollee per year (95% CI: −1.24, −0.16) in the first year after EDIE was mandated, or 8.2% of the baseline ED visit rate among frequent users. However, by the second year of implementation, these effects on ED use were no longer significant, nor were there any measurable effects on inpatient admissions, primary care use, or expenditures in any period. Conclusions: Statewide implementation of EDIE was associated with a small reduction in ED use among frequent users in the first year of the program but did not change overall spending or other utilization outcomes.