Changes in Medication Use During Medicaid Continuous Enrollment and Unwinding.

Importance: During the COVID-19 pandemic, Medicaid enrollment increased because states suspended routine eligibility determinations. After this continuous enrollment provision ended in April 2023, millions of US individuals lost Medicaid coverage. Objective: To measure how the unwinding of Medicaid enrollment was associated with changes in patients' use of health services, such as prescription medications. Design, Setting, and Participants: A cross-sectional study was carried out using interrupted time series analysis to compare changes in quarterly Medicaid enrollment and prescription medication use from 2018, quarter (Q) 1 through 2024, Q1. Data were analyzed from November 2024 to February 2025. Exposures: The onset of continuous enrollment provision (2020, Q2) and unwinding (2023, Q2). Main Outcomes and Measures: The outcomes were quarterly state Medicaid enrollment and estimated number of reimbursed prescriptions. Log-transformed linear regression models were used to compare changes in state enrollment and prescriptions after continuous enrollment and unwinding, overall and stratified by states with different net enrollment changes and policies to protect patients during unwinding. Subsets of medications for certain chronic conditions and formulations primarily used by children were analyzed. Results: In the quarter before the COVID-19 pandemic (2019, Q4), Medicaid enrollment was 71.4 million, and there were about 183.2 million prescriptions reimbursed by Medicaid programs. This included 59.1 million (32.3%) prescriptions treating chronic diseases, 30.3 million (16.5%) for acute conditions, and 15.0 million (8.2%) for other specified conditions. In 2023, Q2, enrollment peaked at 93.9 million (31.4% increase from baseline), and the number of prescriptions peaked at 212.6 million (16.1% increase from baseline). Enrollment increased by 2.42% (95% CI, 2.15%-2.70%) per quarter during continuous enrollment and decreased by 4.92% (95% CI, -6.12% to -3.70%) per quarter during unwinding. Concurrently, the number of prescriptions increased by 1.85% (95% CI, 1.21%-2.50%) per quarter and then decreased by 3.94% (95% CI, -5.73% to -2.11%) per quarter. Trends were similar for chronic disease medications and pediatric-specific formulations. States with the highest disenrollment during unwinding had the largest decreases in chronic disease medication use; states that implemented more protective policies had smaller decreases in enrollment and insignificant decreases in chronic medication use. Conclusions and Relevance: This cross-sectional study found that changes in Medicaid medication use during the COVID-19 pandemic continuous enrollment period and after unwinding were smaller than corresponding changes in enrollment. Unwinding had measurable impacts on patient access to prescription medications, but states that implemented protective policies were able to mitigate these changes.