# Unwinding of Medicaid enrollment and increased uninsured emergency department visits in California

## TL;DR

Medicaid unwinding in California led to fewer Medicaid emergency visits and more uninsured visits, especially in rural and poor areas.

## Contribution

This study quantifies the impact of Medicaid unwinding on ED payer mix and identifies hospital-specific patterns.

## Key findings

- Medicaid ED visits declined by 0.37 percentage points during unwinding.
- Uninsured ED visits increased by 0.16 percentage points per quarter during unwinding.
- Rural and high-poverty hospitals saw the largest increases in uninsured visits.

## Abstract

To examine the association between post–pandemic era Medicaid eligibility redeterminations (“unwinding”) and emergency department (ED) payer mix in California.

We conducted a retrospective secondary analysis of California's quarterly ED visit data (2021–2024) across 281 general acute-care hospitals, using interrupted time-series analysis.

During unwinding, Medicaid ED visits declined by 0.37 percentage points (pp) and uninsured ED visits increased by 0.16 pp per quarter (P < .001) relative to the pre-unwinding period. The largest Medicaid declines occurred in investor-owned (0.87 pp, 11.9%) and medium-sized (0.47 pp, 7.4%) hospitals (P < .001). In contrast, the largest increases in uninsured visits occurred among hospitals in rural (0.29 pp, 46.7%) and high-poverty (0.24 pp, 7.7%) areas, in addition to small hospitals (0.22 pp, 25.8%) (P < .001). Private visits saw an immediate decrease of 0.49 pp (P < .001), followed by a continued reduction of 0.15 pp per quarter (P < .05), showing flattening of the previously increasing trend. Medicare visits increased by 0.18 pp per quarter (P < .001) relative to the pre-unwinding period.

Medicaid unwinding was associated with a decline in Medicaid ED visits and a corresponding increase in uninsured ED visits, with varying impacts across hospital types in California.