Prevalence and predictors of underinsurance among low-income adults.

BACKGROUND: Millions of adults will gain Medicaid or private insurance in 2014 under the Affordable Care Act, and prior research shows that underinsurance is common among middle-income adults. Less is known about underinsurance among low-income adults, particularly those with public insurance.

OBJECTIVE: To compare rates of underinsurance among low-income adults with private versus public insurance, and to identify predictors of being underinsured.

DESIGN: Descriptive and multivariate analysis of data from the 2005-2008 Medical Expenditure Panel Survey.

PARTICIPANTS: Adults 19-64 years of age with family income less than 125 % of the Federal Poverty Level (FPL) and full-year continuous coverage in one of four mutually exclusive insurance categories (N = 5,739): private insurance, Medicaid, Medicare, and combined Medicaid/Medicare coverage.

MAIN MEASURES: Prevalence of underinsurance among low-income adults, defined as out-of-pocket expenditures greater than 5 % of household income, delays/failure to obtain necessary medical care due to cost, or delays/failure to obtain necessary prescription medications due to cost.

KEY RESULTS: Criteria for underinsurance were met by 34.5 % of low-income adults. Unadjusted rates of underinsurance were 37.7 % in private coverage, 26.0 % in Medicaid, 65.1 % in Medicare, and 45.1 % among Medicaid/Medicare dual enrollees. Among underinsured adults, household income averaged $6,181 and out-of-pocket spending averaged $1,115. Due to cost, 8.1 % and 12.8 % deferred or delayed obtaining medical care or prescription medications, respectively. Predictors of underinsurance included being White, unemployed, and in poor health. After multivariate adjustment, Medicaid recipients were significantly less likely to be underinsured than privately insured adults (OR 0.22, 95 % CI 0.17-0.28).

CONCLUSIONS: Greater than one-third of low-income adults nationally were underinsured. Medicaid recipients were less likely to be underinsured than privately insured adults, indicating potential benefits of expanded Medicaid under health care reform. Nonetheless, more than one-quarter of Medicaid recipients were underinsured, highlighting the importance of addressing cost-related barriers to care even among those with public coverage.