Differences in Medicaid Enrollment and Spending Before and During the COVID-19 Pandemic.

Importance: The COVID-19 pandemic and associated continuous eligibility policy were associated with lasting changes to Medicaid coverage and spending. These changes for both adults and children should be assessed to better inform policymakers of potential consequences over the long run. Objective: To compare enrollment and spending patterns for adults and children over the course of 18 months before and during the pandemic. Design, Setting, and Participants: This cohort study used Transformed Medicaid Statistical Information System administrative data to compare cohorts of Medicaid enrollees beginning in February 2018 compared with cohorts beginning in February 2020. Participants included adults and children enrolled in Medicaid in 25 states and the District of Columbia with reliable enrollment and spending data. The data were analyzed between August 31, 2023, and December 9, 2024. Exposures: The COVID-19 pandemic and Medicaid continuous eligibility policy. Main Outcomes and Measures: The primary outcomes were Medicaid enrollment and mean monthly Medicaid spending for cohorts of adults and children. Trends in enrollment and spending over an 18-month period were compared separately for adults and children. A decomposition was used to quantify the contribution of 2 factors-the share of people with any spending and mean spending among enrollees who had spending-to the observed spending differences across the 2 cohorts. Results: In month 1 of each cohort, the samples consisted of 12 352 041 adults (7 525 313 female [60.9%]) in the 2018 cohort, 11 998 538 adults (7 370 318 female [61.4%]) in the 2020 cohort, 14 917 138 children (7 367 579 female [49.4%]) in the 2018 cohort, and 14 585 026 children (7 205 186 female [49.4%]) in the 2020 cohort. The mean (SD) age of the 2018 and 2020 adult cohorts was 37.4 (12.4) years at month 1, and the mean (SD) ages of the 2018 and 2020 child cohorts were 8.8 (5.2) years and 9.0 (5.2) years at month 1, respectively. The pandemic and continuous eligibility policy increased the share of adults still enrolled in Medicaid after 18 months by 28 percentage points among adults and by 19 percentage points among children. The pandemic and policy were also associated with lower mean spending compared with a prepandemic cohort. This gap in spending was largest during the first few months of the pandemic with substantial lockdown policies (22 percentage points lower in adults and 36 percentage points lower in children). Finally, additional enrollees in month 18 of the 2020 cohort had spending that was 44% to 58% lower than that of existing enrollees. Although spending rebounded slightly from start of the pandemic, spending after 18 months still lagged below prepandemic levels. Conclusions and Relevance: In this cohort study, the continuous eligibility policy appeared to be effective at keeping individuals enrolled in Medicaid and additional enrollees had relatively lower spending. Incomplete recovery of spending suggested that crucial care may have been deferred.