Expanding Medicaid Eligibility for Young Adults: Impact on Coverage in Massachusetts
Authors: Dass Deepika , Price Mary , Fung Vicki 
Published: September 2021

Research ObjectiveThe Affordable Care Act (ACA) expanded coverage for young adults by allowing them to remain dependents on their parents' plans until age 26 (in 2010) and expanding Medicaid to childless adults with incomes <138% of the federal poverty level (FPL) (in 2014). However, even post‐ACA, uninsured rates by age group were highest among young adults. In 2014, Massachusetts also expanded Medicaid eligibility for children to 19‐20‐year‐olds with incomes up to 150% FPL, which could reduce potential gaps in coverage for those who would otherwise age out of eligibility for Medicaid as children after age 18. We used the Massachusetts All Payer Claims Database to examine changes in coverage for Medicaid enrollees who turned 19 years old before and after the policy change.Study DesignWe used data from the Massachusetts All Payer Claims Database (MA‐APCD) from 2012–2016 to examine two cohorts: Medicaid enrollees age 18 as of January 2012 and as of January 2014, who turned 19 years old prior to vs. after Medicaid expansion (pre‐ and post‐expansion cohorts, respectively). Monthly coverage changes for each cohort were examined for 2 years until they turned 21 years old (2012–2014 or 2014–2016). We classified months without insurance enrollment records as uninsured. We used logistic regression models to compare the likelihood of being uninsured for 3 or more months at age 19–20 and 20–21 for the pre‐ vs. post‐expansion cohorts, adjusting for gender, diagnoses of asthma, autism, obesity, mental illness, and intellectual and development disabilities, and ZIP code socioeconomic status (SES).Population StudiedMedicaid enrollees age 18 in January 2012 (N = 32,832) and January 2014 (N = 31,894) in the MA‐APCD.Principal FindingsIn both cohorts, 49% were female and 29% lived in low SES ZIP codes; those who turned 19 prior to vs. after Medicaid expansion were less likely to have a baseline diagnosis of asthma (12.1% vs. 12.9%, p < 0.05), obesity (7.6% vs. 8.7%, p < 0.05), and mental illness (17.4% vs. 18.8%, p < 0.05). Enrollees who turned 19 prior to vs. after Medicaid expansion were more likely to have ≥3 months of commercial insurance at age 19–20 (8.5% vs. 3.6%; OR = 1.85, 95% CI 1.7, 2.0) and ≥ 3 months without insurance (17.0% vs. 1.2%; OR = 20.3, 95% CI 17.4, 23.6). Differences persisted at age 20–21, although both cohorts had access to Medicaid expansion for low‐income adults in these years (7.6% vs. 4.9%, OR = 1.4, 95% CI 1.3,1.6 for ≥3 months of commercial insurance; 11.5% vs. 0.9%, OR = 16.4, 95% CI 13.7, 19.5 for ≥3 months without insurance).ConclusionsDisruptions in insurance coverage for young adults aging out of Medicaid were substantially reduced in Massachusetts after the state expanded Medicaid for children to cover 19–20‐year‐olds and expanded coverage for low‐income adults. Commercial insurance coverage was also less likely for young adults after Medicaid expansion. Medicaid enrollees that entered adulthood prior to vs. after Medicaid expansion were more likely to be uninsured in years after Medicaid expansion.Implications for Policy or PracticeExpanding Medicaid eligibility for children to those ages 19–20 could substantially reduce the risk of becoming uninsured for low‐income children entering young adulthood.Primary Funding SourceAgency for Healthcare Research and Quality.