Prevalence, Awareness, and Control of Chronic Health Conditions Among Low-Income Adults with Medicaid Compared to Private Insurance

Under the Affordable Care Act (ACA), states have the option to expand Medicaid eligibility to more low-income adults using federal Medicaid funds through 2016.  Some states are proposing to provide premium assistance to purchase coverage for some or all Medicaid beneficiaries in the new marketplaces instead of traditional Medicaid plans. This raises questions of how well  traditional Medicaid programs care for low-income adults compared to care provided by private insurance plans. 

The paper compares measures of access to and quality of care among low-income adults on Medicaid and private insurance.  National Health and Nutrition Examination Survey (NHANES) 1999-2010 data were used to obtain a nationally-representative sample of 1,357 adults on Medicaid and 2,877 privately insured  aged 20 through 64 years with income no more than 200% of the federal poverty level. The NHANES consists of household interviews, in-person physical examinations, and laboratory tests.  We estimated unadjusted and adjusted differences in health care use and knowledge and control of diabetes, hypertension, and hypercholesterolemia among low-income adults with Medicaid compared to private insurance.  Adjusted differences were derived from a logit regression and an instrumental variables (IV) regression while controlling demographic, health, and socioeconomic characteristics of respondents. The IV model addresses potential bias from unobserved characteristics that may be correlated with type of insurance coverage. The instrument uses information on adult eligibility rules by state and year developed by the Urban Institute following the general approach of Currie and Gruber (1996) for children.  Unobserved state-level characteristics that may also affect outcomes are addressed by the inclusion of state fixed effects.

Low-income adults on Medicaid were more likely (about 92 percent) than those with private insurance (about 84 percent) to have seen a health care professional in the past year and to have a usual source of care.  However, adjusted estimates indicated that health care access was generally similar for the two groups, though when there were statistically significant differences, they indicated higher service use for low-income adults with Medicaid.  Awareness and control of chronic conditions were generally similar for low-income adults on Medicaid compared to privately insured.  Among those with hypertension, hypercholesterolemia, or diabetes, about one-quarter had at least one of the conditions (based on clinical measures) but were unaware of it (based on self-report) and about three-quarters had at least one of the conditions uncontrolled (based on clinical measures).    Even adjusting for covariates and instrumenting for Medicaid status, however, there was evidence that low-income adults with  hypertension were more likely to have it under control if they had Medicaid coverage as opposed to private coverage.

These results suggest that there is substantial room for improvement in the diagnosis and treatment of chronic conditions for low-income adults with both Medicaid and private coverage.  There is no evidence to suggest that low-income adults with private coverage have better access to care or better control of these chronic conditions; the evidence suggests that (if anything) the opposite may be the case.