Medicaid Disenrollment Among Young Adults With and Without Complex Medical Conditions.

Importance: Loss of health insurance coverage is common as Medicaid-enrolled children transition to adulthood and increases morbidity and mortality, especially for individuals with complex medical conditions (CMCs). Objective: To measure risk of Medicaid disenrollment in young adults with and without CMCs and variation by medical condition and state of residence. Design, Setting, and Participants: This retrospective observational study was conducted among individuals in 47 state Medicaid programs born 1991-2001 with 11 or more months of comprehensive Medicaid coverage in 2016 using the 2016-2019 Transformed Medicaid Information Systems Analytic Files, a census of Medicaid administrative medical claims (N = 9 409 619). Individuals with CMCs were identified in 2016 using the Pediatric Medical Complexity Algorithm. Age-based risk of disenrollment and reenrollment for individuals aged 16 to 26 years with and without CMCs was estimated from 2017-2019 using discrete-time survival models. Cumulative risk of disenrollment in individuals aged 19 to 21 years was measured using Kaplan-Meier curves. Analyses were stratified by state and medical condition. Data were analyzed from October 2024 to September 2025. Main Outcomes and Measures: The primary outcome was probability of disenrollment, defined as 2 or more months with no days of comprehensive benefits. The secondary outcome was reenrollment, defined as any days of comprehensive benefits within 12 months of disenrollment. Correlates of disenrollment were measured at individual and state levels. Results: A total of 305 323 individuals (3.2%) were identified as having a CMC in 2016. Disenrollment peaked at age 19 years; conditional probability of disenrollment was 13.4% (95% CI, 13.2%-13.6%) among individuals with CMCs and 35.6% (95% CI, 35.6%-35.7%) among individuals without CMCs. Probability varied by state, ranging from 2.6% (95% CI, 2.0%-3.2%) to 37.0% (95% CI, 34.7%-39.4) for individuals with CMCs and from 7.3% (95% CI, 6.7%-7.9%) to 83.9% (95% CI, 83.5%-84.3%) for those without CMCs. Among individuals with a CMC, mental health and cardiac conditions had the highest probability of disenrollment at age 19 years. Cumulative risk of disenrollment was 37.9% (95% CI, 37.3%-38.6%) among individuals with CMCs and 74.2% (95% CI, 74.1%-74.3%) among those without. Higher conditional probability of disenrollment was correlated with being male, eligiblity via income, living in a Medicaid nonexpansion state, and living in a state with 50% or more managed care penetration. Of disenrolled individuals, 38.0% (95% CI, 37.6%-38.4%) of those with CMCs and 29.1% (95% CI, 29.0%-29.1%) of those without CMCs reenrolled within 12 months. Conclusions and Relevance: In this cohort study, disruptions in Medicaid coverage were common for emerging adults with and without CMCs and varied by state and condition.