PHP9 - DETERMINING THE FEASIBILITY OF USING A REGRESSION DISCONTINUITY APROACH TO COMPARE EMERGENCY ROOM UTILIZATION BETWEEN MEDICAID FEE-FOR-SERVICE AND COMMERCIALLY OBTAINED COVERAGE IN THE ACA MEDICAID EXPANSION POPULATION

Abstract

Arkansas implemented a premium assistance strategy to provide individual commercial health insurance for the Medicaid expansion population of the Patient Protection and Affordable Care Act. To mitigate adverse selection, a 12 item patient reported frailty screener, ranging from 0.023 - 1 was used to assign individuals with higher health needs (frailty score > 0.1799) to traditional Medicaid coverage instead of commercial insurance. The objective of this study was to determine the feasibility of using a regression discontinuity (RD) framework to contrast the rates of overall emergency room (ER) use, mental health related ER use and potentially preventable ER use between patients assigned to traditional Medicaid and patients enrolled in commercial insurance. Our study was comprised of ambulatory, non-incarcerated newly enrolled persons between 18 and 64 years of age, who had least 180 days of stable enrollment in commercial insurance or Medicaid in 2014 and completed a frailty screener prior to enrollment. Administrative claims data from Medicaid and two of the commercial insurers providing coverage to the Medicaid expansion population were used to calculate the rates of overall ER, mental health related ER and potentially preventable ER use. To explore the feasibility of using RD, we stratified ER rates by frailty score deciles and estimated a linear regression to test the association between the pre-score (frailty score) and our outcome measure. Our sample was comprised of 17,453 subjects of which 10,894 were above the frailty cut-point. A positive linear trend was observed between overall ER use (β=1,917; p=0.2443), mental health related ER use (β=355; p=0.0999), and potentially preventable ER use (β=979; p=0.3223) and frailty score. All three ER measures showed a positive linear trend association with the frailty score thus supporting future application of the RD framework for inferential analysis.