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Impact of Subsidized Health Insurance Coverage on Emergency Department Utilization by Low-income Adults in
Jennifer Lee1, Ru Ding, Scott L Zeger
1Departments of *Emergency Medicine †Health Policy, George Washington University, Washington, DC ‡Department of Biostatistics, Johns Hopkins University, Baltimore, MD §Massachusetts Division of Health Care Finance and Policy, Boston ∥Health Connector Authority, Shrewsbury ¶Health Safety Net, Division of Health Care Finance and Policy, Executive Office of Health and Human Services, Boston, MA #Department of Health Policy, Department of Emergency Medicine, George Washington University, Washington, DC.
Background:
In 2006, Massachusetts expanded insurance coverage to many low-income individuals.
Objectives:
This study aimed to estimate the change in emergency department (ED) utilization per individual among a cohort who qualified for subsidized health insurance following the Massachusetts health care reform.
Research Design:
We obtained Massachusetts public health insurance enrollment data for the fiscal years 2004-2008 and identified 353,515 adults who enrolled in Commonwealth Care, a program that subsidizes insurance for low-income adults. We merged the enrollment data with statewide ED visit claims and created a longitudinal file that indicated each enrollee's ED visits and insurance status each month during the preenrollment and postenrollment periods.
Measures:
We estimated the ratio in an individual's odds of an ED visit during the postperiod versus preperiod by conditional logistic regression.
Results:
Among the 112,146 CommCare enrollees who made at least 1 ED visit during the study period, an individual's odds of an ED visit decreased 4% [odds ratio (OR)=0.96; 95% confidence interval (CI), 0.94, 0.98] postenrollment. However, it varied significantly depending on preenrollment insurance status. A person's odds of an ED visit was 12% higher in the postperiod among enrollees not publicly insured prior (OR=1.12; 95% CI, 1.10, 1.25), but was 18% lower among enrollees who transitioned from the Health Safety Net, a program that pays for limited services for low-income individuals (OR=0.82; 95% CI, 0.78, 0.85).
Conclusions:
Expanding subsidized health insurance did not uniformly change ED utilization for all newly insured low-income adults in Massachusetts.
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