Enrollment in California's Medicaid Program After the Affordable Care Act Expansion

To determine enrollment rates and predictors of enrollment for newly eligible low-income adults in California following the Affordable Care Act's (ACA's) Medicaid expansion.

We used data from the 2014 to 2015 California Health Interview Survey to examine post-ACA Medicaid enrollment rates and multivariable logistic regression to assess the association of demographic factors, income, and health with enrollment.

We found a 78.5% enrollment rate for the newly eligible Medicaid population, translating to 3.8 million adults enrolled and 1.1 million adults who were eligible but did not enroll. Significant predictors of enrollment were participating in a public welfare program (odds ratio [OR] = 6.59; 95% confidence interval [CI] = 3.09, 14.04), having heart disease (OR = 4.03; 95% CI = 1.34, 12.15), being in the top quartile of income (OR = 3.59; 95% CI = 1.64, 7.85), enrolling in 2015 (OR = 3.28; 95% CI = 1.94, 5.56), being unemployed (OR = 2.10; 95% CI = 1.15, 3.82), and being female (OR = 1.71; 95% CI = 1.03, 2.85). We did not find significant disparities across race/ethnicity, education level, or geography.

Repeal of Medicaid expansion would have a substantial effect on health insurance coverage among California's low-income adults, many of whom report chronic health conditions and no alternative sources of affordable coverage. Future research should examine the mechanisms explaining the higher enrollment rates among California's Medicaid expansion population.