32 - Medicaid enrollment at ages 19 – 20 years among youth aging out of Pediatric Medicaid eligibility

Publication Number: 3029.32

EMILY GREGORY, Children's Hospital of Philadelphia, PHILADELPHIA, PA, United States; Eric Roberts, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA, United States; Sindhu Srinivas, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA, United States; Dylan Small, UNIVERSITY OF PENNSYLVANIA, Philadelphia, PA, United States; Alexander S. Hill, Children's Hospital of Philadelphia, Glenside, PA, United States; Molly Passarella, Childrens Hospital of Philadelphia, Philadelphia, PA, United States; Scott A. Lorch, The Children's Hospital of Philadelphia, University of Pennsylvania, Philadelphia, PA, United States

Background: Medicaid and CHIP provide health insurance for 40% of US youth. Little is known about Medicaid enrollment among youth aging out of pediatric Medicaid eligibility. Starting 1/2014, some states expanded Medicaid coverage for low-income adults.

Objective: Examine Medicaid enrollment at 19 – 23 years for youth aging out of pediatric Medicaid. Analyze differences in enrollment at 19 – 20 years, comparing states that expanded Medicaid eligibility and those that did not.

Design/Methods: This cohort study used Medicaid Analytic Extract (MAX) and Transformed Medicaid Statistical Information System (T-MSIS) for youth born 1989 – 1992 (pre-expansion cohort) and 1995 – 1998 (post-expansion cohort) who had ≥6 months of Medicaid enrollment at ages 17 – 18 years. We excluded at the level of the state-birth year if there was substantial loss in the MAX to T-MSIS transition. We followed youth through age 21 – 23 (12/2013 for the pre-expansion cohort, 12/2019 for the post-expansion cohort). We examined 2 measures of Medicaid enrollment: enrollment months, and ≥9 months per year, stratified by sex. To analyze differences in expansion versus non-expansion states, we conducted differences-in-differences regression analyses. We used Poisson regression for the dependent variable of enrollment months, and logistic regression for proportion with ≥9 months coverage. For all models, the difference-in-differences estimator was an interaction term between expansion state indicator and cohort. All models adjusted for sex, race and ethnicity, rural zip code, birth year, and state. Regression excluded states that adopted the Medicaid expansion between 2/2014 and 12/2019.

Results: We included 14,513,949 individuals in 46 states (Table 1). Enrollment months and proportion with enrollment ≥9 months were higher among individuals with female sex and younger age (Fig 1). Difference-in-differences regression included 8,600,990 individuals in 23 Medicaid-expansion states and 13 non-expansion states. Expansion was associated with a relative increase of 12% in enrollment months at age 18 (IRR 1.12, 95% CI 1.12 – 1.12) and an increase of 25% at age 19 (IRR 1.27, 95% CI 1.27 – 1.28). Expansion was also associated with increased odds of ≥ 9 months Medicaid at ages 19 (OR 1.21, 95% CI 1.21 – 1.22) and 20 (OR 1.49, 95% CI 1.48 – 1.50).

Conclusion(s): Medicaid enrollment falls after youth age out of pediatric Medicaid eligibility, yet a substantial proportion maintain enrollment. The Medicaid expansion was associated with increased enrollment at ages 19 – 20 years.

Table 1: Characteristics of cohorts
pas_churn_20251103_table.pdf

Figure 1: Enrollment at ages 19 - 23 years
pas_churn_20251103_fig.pdf