Panel Paper: The Effects of Medicaid on Access and Adherence to Recommended Preventive Services

Friday, November 9, 2018
Madison B - Mezz Level (Marriott Wardman Park)

*Names in bold indicate Presenter

Salam Abdus and Steven C Hill, Agency for Healthcare Research and Quality

Increasing access to preventive care is an important policy goal. Using recent changes in the Medicaid program and control function methods, this paper quantifies the effects of Medicaid on adult beneficiaries’ access to care and adherence to recommended preventive services. We study receipt of services recommended by the United States Preventive Task Forces (USPSTF) within the time frames recommended by the Task Force for the appropriate populations. While some Medicaid studies have examined preventive service use in the past year, the recommended intervals for these preventive services by the USPSTF vary widely. To our knowledge, our study is the first to examine the causal effects of Medicaid on adherence in recommended time frames.

Medicaid eligibility criteria vary across states and time. Before 2010, the median income eligibility threshold across the 50 states and the District of Columbia for full Medicaid benefits for non-working parents was 38% of the federal poverty level (FPL). In most states, childless adults were unable to obtain Medicaid. Only six states used federal waivers to offer full benefit Medicaid coverage to nondisabled childless adults, and twelve additional states offered limited benefits, but many of these latter programs were closed to new applicants. Starting in 2010, states had more latitude to expand eligibility to most residents with incomes less than 138% FPL. Starting in 2014, the federal government generously subsidized states that expanded Medicaid eligibility. As of early 2018, 31 states and the District of Columbia had expanded their Medicaid programs under the ACA.

The nationally representative sample is low-income, non-elderly adult citizens in the Medical Expenditure Panel Survey for 2005–2015, which spans the business cycle. We use probit control function methods to account for binary outcomes and binary enrollment measures. We instrument for enrollment with Medicaid eligibility rates derived from a detailed simulation model. We simulate eligibility through a comprehensive set of Medicaid eligibility categories. We apply these rules to a sample of nonelderly adults drawn from the 2005 to 2015 Medical Expenditure Panel Survey (MEPS). To create our instrument for enrollment, we estimate eligibility rates that hold the population constant in the same manner as Currie and Gruber (1996). That is, we apply the rules of each state-year to the entire sample and create separate estimates by state, year, parental status, sex, race/ethnicity, and age, education or income bands. The population-constant eligibility rate is highly predictive of enrollment.

Medicaid improved key outcomes for enrollees. Medicaid enrollment increased the probability of having a usual source of care by 16.4 percentage points, having a check-up in the past year by 7.9 percentage points, getting a flu shot by 5.7 percentage points, having one’s blood pressure checked in the past two years by 7.2 percentage points, and having a Pap smear in the past 3 years by 12.7 percentage points. Medicaid enrollment reduced the probability of having unmet needs for medical care by 7.0 percentage points, unmet needs for prescription drugs by 5.5 percentage points, and delays getting prescription drugs by 5.1 percentage points.