Does growing insurance coverage under the Affordable Care Act (ACA) reduce access to care for the insured?

The Affordable Care Act (ACA) expanded insurance coverage through Medicaid, the Marketplace, and financial incentives. Affordable coverage may lead to increased demand for health care among the newly insured, but the short-run supply elasticity of health care services is also critical for access. If providers had excess capacity, then demand could be easily met, but many observers expressed concern that providers could not supply enough additional services.  The influx of new patients could reduce access to care for people who had insurance before the ACA, especially in states with the largest gains in the insured as a percentage of the population.  The percentage of the population with insurance grew by at least 5 percent in 2014 in several states, including California. On the other hand, the ACA includes several efforts to shift the supply curve out.  The ACA provides funding to:  train more physicians, mid-level practitioners, and nurses; encourage more providers to work in underserved areas; expand federally-qualified health centers; and temporarily increase some Medicaid fees for primary care providers.  The net effect of the ACA on access is an open question for those insured before the coverage expansion and those who remained uninsured.

We examine whether access to care has improved or deteriorated for adults in 2014, using Medical Expenditure Panel Survey (MEPS).  The MEPS collects detailed measures of aspects of access that may be especially affected by supply.  These measures are how easy it is to:  get appointments for routine care, get care needed right away, get appointment with specialists, and get needed care, tests or treatments.  The MEPS also asks about having a usual source of care and unmet needs and delays in getting medical care.

Using the MEPS two year panels and the linkage to the National Health Interview Survey, we identify adults who had the same source of insurance in 2013 and in 2014, and analogously for older panels.  Pooling 7 years (2008 to 2014), we regress access measures on the growth in the number of insured, demographic and socioeconomic variables, and state fixed effects.  This specification allows us to use changes in the percent insured related to program expansions and contractions before and in 2014.  Measures of insurance growth from the American Community Survey provide additional sub-state variation.  We also estimate specifications with discrete variables for geographic unit-years with large increases in insurance coverage.  Effects may also depend on the number of physicians per capita, so we test for interactions between growth in the number of insured and the physicians per capita. 

Our previous analysis suggests that the trends in some access measures were different between those with private and public coverage. Therefore we run separate regressions for those with Medicaid and employer-sponsored insurance (ESI).  The providers who serve Medicaid beneficiaries may serve very few people with ESI, and vice versa.  Therefore, as a sensitivity analysis of access for adults with Medicaid, we re-estimate the regression with growth in Medicaid enrollment (as measured in administrative data) as the independent variable.