The Impact of Health Insurance on Healthcare Utilization and Health: Evidence from Medicaid Expansion in Wisconsin
58 Pages Posted: 5 Aug 2024
Date Written: July 25, 2024
Abstract
We extend the Oregon Health Insurance Experiment (OHIE) study of the effects of gaining health insurance by reporting large-sample, time-series evidence, from difference-in-differences analysis of visit-level healthcare records, before and after Wisconsin’s Medicaid expansion in 2014 to cover childless adults with incomes up to 100% of the federal poverty limit. We follow these persons over 2011-2022 using electronic health records (EHR) records for a major, Milwaukee-based health system and compare healthcare use for newly-Medicaid-enrolled childless adults aged 36-64 (treatment group) with a propensity-score-balanced control group of previously enrolled persons. Gaining health insurance leads to a sharp, immediate, rise in health care utilization. Outpatient visit rates roughly double, to levels similar to the control group. ED visit and hospitalization rates jump from well below to well above the control group, but after about two years fall back to control-group levels. ED visits rise for both visits leading to discharge and (unlike OHIE) visits leading to hospital admission. Gaining insurance leads to large, sustained increases in new chronic-disease diagnoses, medication prescriptions (e.g., diabetes, cholesterol, blood pressure), testing rates, and lower levels for chronic disease markers (glucose, cholesterol, blood pressure, but no change in macrovascular events. Treatment effects are broadly similar across gender, race/ethnicity, and age.
Note:
Funding Information: Research support came from NIH, National Center for Advancing Translational Sciences, Award UL1TR001436.
Declaration of Interests: The authors declare no conflict of interest.
Ethics Approval Statement: This research was approved by the Medical College of Wisconsin institutional review board. The parallel Indiana study was approved by the Chicago Area Institutional Review Board.
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